Equipment and technology for magnetic pulsed processing of metals

Magnetic-pulse arrays are intended for implementation of a wide spectrum of process operations: drop forging, cutting, assemblage, impulse welding of plane and hollow workpieces made of electroconductive materials in a batch and small batch production.


mechanical engineering (aviation, space-rocket, motor industry);

electrotechnical and instrument engineering, as well as scientific studies in Fields of impulse techniques.


one-piece structure

Controlled by means of an offset remote console at the distance of up to 10 meters.

Max current up to 1000 кА.

Max accumulated energy 200 kJ

Range of working tensions - 1-50 kV with a pitch of 0,5 kV.

Firmware monitoring system of discharge parameters.

Protection against overloads of current and voltage.

Automatic discharge of residual stress and interlock of unauthorized switching on.

Resistance to single overloads at electric breakdown of inductor's insulation.

Power supply: three-phase - 380-400 VAC, capacity-20 kVA.

Example of magnetic-pulse treatment of metal and composite workpieces

Usage of magnetic-pulse technics at various operations






Samples of joints:

Joints of aluminum and kaprolon





Coal plastic-metal




Instance it is magnetic-pulsing technics of reduction of cable lugs

The machining attachments

The punched device

The cutting, chopping device

otbortovochnoe the device

The forming device

The mounting device





Application is magnetic-pulsing technics

Ranges of application of MPPM are considerably widened at the expense of magnetic-pulse effect on liquid and crystallizing metallic melts (figure 4).

figure 4
Figure 4 - Fields of technical application of magnetic-pulse effect on liquid and crystallizing metallic melts

For example, with reference to foundry there was designed a method of physical effect of a pulsing magnetic field on melts for the purpose of forming of pattern and properties of casts. It has been ascertained that magnetic-pulse effect allows obtaining a dense fine grained structure of silumins (a figure 5).

1 2

Without treatment

After treatment W=0,56 kJ,
n=3 pulses × 200

3 4

Without treatment

After treatment W=0,56 kJ,
n=3 pulses × 1000

Figure 5 Influence of parameters of magnetic-pulse effect on a microscopic structure of Al-6 of % Si alloy

Such modifications in the pattern of the cast metal have a favorable effect on foundry and mechanical characteristics of casts.
So, castability rise makes 20 %, ultimate strength - 20 %, and specific elongation is augmented in 2,7 times.

Technics of effect of magnetic-pulsing process on a melt for the purpose of modification of its pattern

Application of magnetic-pulsing technics for improvement of casting quality

MPT axial effect on a melt

MPT effect on a melt bulk

MPT of radial effect on a melt

Application of MPPM in electric power saving in aluminum production

Application of MPPM in electric power saving in aluminum production

One of developing directions of melt treatment by a pulsing magnetic field is forming of cast electrocontact plugs (ECP) in graphitized carbon anodes for metallurgical production.

Magnetic-pulse effect ensures contact enhancement between ECP and a graphitized carbon material that results in decrease of transfer resistance on the interface in tens and hundreds of times.

The samples have been obtained under following parameters of pulse magnetic treatment:

Discharge energy: 0,66 kJ, 1 ku, 1,32 kJ

Number of pulses: 10

Used materials:

- aluminum alloy AK9ч;

- coke carbon blocks, material of IFU type.




Channel filling up for air removal:

a) Sample without PMP;

b) Sample with PMP 1,32 kJ

Figure 6 shows adhesion of cast metal to a graphitized carbon block before magnetic-pulse effect.



Without magnetic-pulse effect

After magnetic-pulse effect

Figure 6 - Adhesion of metal to a graphitized carbon block

The produced effect is capable to lead to saving of millions of kW of electric power in production of non-ferrous metals, for example, aluminum and magnesium by electrolysis method.

Application is magnetic-pulsing technics for "curing" of incipient cracks in metallical details and constructions

The page is in development

Application is magnetic-pulsing technics for reconditioning of tubes NKT without uprise

Hydrosulphuric medium is a place where live and propagate SULPHATE-REGENERATIVE BACTERIA which products are very aggressive and aggregations of the bacteria ptoduce major and small openings in metal. Onset of openings in lifting pipes and casing pipes result in the ANNULUS BLOWOUT of oil and it is bad. The technics which realizes sweeping reconditioning of the produced openings by means of MAGNETIC PULSE is offered.

Essence of the method: a special gadget equipped with with an INDUCTOR and corrosion-proof PIPE is positioned in area of the OPENING and after the feeding PULSE to the INDUCTOR the corrosion-proof tube tightly fits to the walls of the repaired tube closes down the ANNULUS BLOWOUT.

The technics is energy saving, allows to repair sections of tubes on the depth up to 7000 m.
Diameters of repaired tubes from 76 to 350 mm.

magnetic-pulse technics for fabrications of earth connections

Bimetal earth connection

One of the basic expedients of safe operation of electrics is construction of bonding connections. These devices consist of underground groundwire and a grounding conductor. In Russia as groundwire steel rods which one are subject to rapid corrosion in the ground are used, as a rule, that it in turn results in magnification of the bonding connection resistance. In this connection there is a necessity of periodic checks of their state including with excavations that is a labor-consuming and costly intensive operation. In the USA according to the Standard for grounding and bonding equipment it is possible to use bimetal earths electrode consisting of an interior steel rod and an outer copper housing. Durability of similar bonding connection 10 times exceeds a service life of usual steel. To ensure a reliable connection one of the Yugoslavian corporations proposed an explosion welding operating procedure. However, the explosive technics has a row of essential deficiencies, such as high complexity, tough requirements to the safety of works and storage of explosives. There was designed a new construction and manufacturing methods of bimetal bonding connections.

Geometrical parameters of bonding connections:

- Outer diameter - 14... 22 mm;

- Length - 2,5 m;

- Width of a copper envelope - 0,5 … 1,0 mm.

Press-fitting and welding of a housing are carried out under stress of a pulsing magnetic field. The basic advantages of the designed technics:

- high efficiency of the process;

- possibility of manufacturing of lengthy articles with low energy equipment at the stage-by-stage operation of deforming;

- possibility of usage of standard tubes for a housing;

- low cost of production tools;

- profitability and high corporate culture, etc.

The tests of the samples have demonstrated their compliance with requirements of the Standard for grounding and bonding equipment.

Operating instructions and user manuals

magnetic-pulse UNIT



Ukhta 2008


1 DESIGNATION.................................................................................................................3
2 TECHNICAL DATA AND CHARACTERISTICS............................................................3
3 UNIT COMPOSITION.....................................................................................................4
4 UNIT DESIGN AND OPERATION..................................................................................5
4.1 Principle of operation........................................................................................................5
4.2 MPU design.....................................................................................................................6
4.3 Basic diagram description.................................................................................................8
5 DESIGN OF COMPONENTS.........................................................................................11
5.1 Charger...........................................................................................................................11
5.2 Energy store....................................................................................................................12
5.3. Start unit........................................................................................................................12
5.4. Energy setting block.......................................................................................................13
5.6 MPU circuit element supply.............................................................................................14
5.7 Outlet terminal kit............................................................................................................14
6 PLACEMENT AND ERECTION.....................................................................................15
6.1 MPU placement requirements..........................................................................................15
6.2 MPU erection..................................................................................................................16
7 SAFETY REQUIREMENTS.............................................................................................17
8 SETTING-UP PROCEDURES.........................................................................................18
9 OPERATION PROCEDURE...........................................................................................19
10 MAINTENANCE...........................................................................................................20
11 TRANSPORTATION AND STORAGE.........................................................................23
12 TROUBLESHOOTING AND OTHER RECOMMENDATIONS..................................24

Technical specification and operation manual (OM) contain description of magnetic-pulse unit design, principle of operation, the rules of erection, maintenance and operation.
To get certified for the unit operation, beside this OM, “Safety instruction for operation of magnetic-pulse unit MPU-50U” – 401E.200.000 SI shall also be studied.
In OM, the following notations are accepted:
MPU – magnetic-pulse unit;
ES - energy store;
Ch – charger;
FT – frequency transducer;
RC – remote control;
EDB - Energy dosage block.

1.1 magnetic-pulse unit MPU-50U is designed for treatment of metals by pulse electromagnetic field pressure during performance of various technological operations: molding, calibration, assembling, etc.
1.2 The unit may be operated in dry inexplosive premises, with the atmosphere containing no electroconductive dust, vapors and gases which corrode metal parts and deteriorate electrical insulation of high-voltage MPU electrical systems.
1.3 Operation conditions:
- ambient air temperature from +5 to +40°C;
- relative humidity up to 80% at +25°C.

2.1 Maximum stored energy at synchronous discharge of two ES is 50 kJ.
2.2 Energy store capacity, total, μF – 265.6.
2.3 Discharge current frequency at short-circuit, not less, kHz – 28.
2.4 Self-inductance of MPU discharge circuit, µН – 0.122.
2.5 ES charging voltage varies in the range of 1 – 19.5 kV and is changed with 0.5 kV step.
2.6 The dependence of stored energy on charging voltage is shown in Table 1,
where: U0 is the charging voltage, kV; W0 is stored energy, kJ.
Table 1. Dependence of stored energy on charging voltage

U0 (kV)











W0 (kJ)











U0 (kV)











W0 (kJ)











U0 (kV)











W0 (kJ)











U0 (kV)











W0 (kJ)











2.7 Production rate of operation at stored energy of 40 kJ is 120 operations per hour or less.
2.8 Maximal operating level of stored energy at oscillatory type of discharging current (ES battery discharge depth with voltage polarity reversal up to 80%) is 40 kJ or less.
2.9 The average operational life of ES batteries at charging voltage of 17 kV, the number of pulses is 50,000.
2.10 The average power demand at operation with 40 kJ energy is 20 kVA or less.
2.11 MPU is supplied from three-phase line of 380...400 VAC.
2.12 Overall dimensions: - power unit - 1800 х 800 х 1600 mm;
- control terminal - 300 х 220 х 130 mm.
2.13 Masses of MPU components, below, kg: power unit – 800 kg; control terminal – 5 kg.

- MPU-50U power unit - 1 piece;
- Control terminal - 1 piece;
- Discharge stick - 1 piece.

4.1 Principle of operation
MPU principle of operation is based on the method of direct conversion of electric energy stored in ES batteries to electromagnetic field formed in an inductor at discharge of pulse batteries of the energy store. Electromagnetic field of the inductor induces eddy currents in a preform of processed part. Inductor’s electromagnetic field interaction with currents in the preform produces deformation work and causes pulse heating of the part.
The magnetic-pulse unit consists of two modules of energy stores. ES1 and ES2 modules comprise batteries of 5 and 6 pulse capacitors, respectively, connected to a discharger by a busbar system with minimal self-inductance. At MPU outlet terminals each discharger of the ES module is united by a flat busbar.
ES is charged from general charging unit. Discharge on the inductance load is oscillatory single-shot, discharge current frequency defined by the load inductance.
For stable operation of the unit, synchronous switching on of two dischargers shall be provided. This is obtained by application of quick-operating vacuum arresters having low reaction delay and a special system for arresters synchronization from general actuating pulse.
The functional diagram of MPU is shown in Fig. 1.
Syncronism of operation of two ES blocks is provided by switching on quick-operating arresters F1 and F2 from dual-channel start unit 5. The latter is controlled by general trigger signal generator 7.
Charging unit 2, control system 6 and residual voltage circuitor Fs are general for two energy stores, ES1 and ES2. Frequency converter 1 in the MPU power circuit is designed for controlling the charge current, provides smooth start of MPU and uniform loading of power circuit phases. ES is charged from general charging unit 2 by direct voltage. As voltage on capacitors С1 … С11 reaches the given value, the energy dosage blocks 3, 4 stop charging by "Stop" command and actuate the trigger signal generator 7.
The initiating pulse of 6 kV voltage from the unit 5 starts dischargers F1, F2, which discharge the energy stores on the working inductor synchronously. At the moment of ES discharge, a pulse current of 50…500 kA amplitude and 50…1000 ms duration flows in the inductor, depending on the stored energy level and working inductor parameters.

Fig. 1. Functional diagram of MPU-50U unit

To protect personnel from residual high voltage on ES batteries after the charge-discharge cycle end, the control unit 6 gives “Reset” command to the circuitor Fs, which automatically discharges high-voltage MPU circuits after the main discharge by removing the residual charge from ES batteries.
When two ES modules are used, working synchronously, two problems are solved: the first problem consists in limitation of energy liberation at the place of damage (capacitor or busbar insulation breakdown) in emergency modes during ES charging. The second task is reduction of total inductance of MPU at parallel connection of two discharging circuits.
Frequency transducer 1 converts 380 V alternate voltage of industrial frequency to pulse voltage of 600 V and 1 kHz frequency. FT applies a method of pulse-width modulation with smooth variation of output pulse ratio. This method provides MPU “soft” start, ES batteries are charged by the linear law, close to optimal that increases the service life of capacitors. As a standard high-voltage converter of 10 kV class, with primary to secondary voltage ratio of 230 V/10 kV, increased frequency of 1 kHz and 600 V voltage is supplied, the outlet voltage we get is above 20 kV.
The control unit provides two operation modes: manual and automatic. In the manual mode, ES charging to the desired level is initiated by “Start” command, and discharging is initiated by “Discharge” command given by the operator. In the automatic mode, a single-shot charging-discharging cycle by a single "Start" command is performed.
4.2 MPU design

The exterior view of the unit is shown in Fig. 2.

Fig. 2. MPU-50 external view

Structurally, MPU consists of the basic power unit and remote control terminal. MPU power unit represents a sectional metal structure consisting of three sections.
Disposition of the main parts and blocks is shown in the drawing 401E.200.000 ME.
Section 1 comprises control system panels and blocks, high-voltage converters of charge and arrester start unit supply, frequency transducer and high-voltage rectifier.
Sections two and three comprise ES batteries, which are electrically united at the arrester block by a cable busbar. The arrester block is combined with outlet terminals of MPU. To reduce inductance of the discharging circuit, each capacitor in ES is connected by a system of five coaxial cables.
Beside ES batteries, the section 2 comprises arrester starting block and arrester unit. On the front panel of the second section, the clamping device 4 with MPU outlet terminals for inductor connection is mounted.
On the side panel 6 of the section one trim, the following elements of external connections are located:
- a cable input of power line;
- a socket for remote control terminal cable connection;
- a terminal for grounding wire connection from MPU to the workshop grounding grid and discharge stick connection.
The discharge stick 5 is mounted on the section three case arm.
MPU is controlled by the remote control terminal, which panel comprises: control organs, signal indicators, kilovoltmeter for current voltage of the charge.
The inductor may be connected to MPU directly via outlet terminals or transition coaxial cable.
4.3 Basic diagram description
The circuit diagram of MPU-50U is shown in the drawing 401E.200.000EZ.
4.3.1 MPU switching on and setting-up procedures.
Light indicator LP1 indicates the presence of supply voltage on inlet terminals A, B and C of MPU. Switch S1 located on the front panel of the first section supplies power to the control circuit and frequency transducer A1.
The control system is set to operation, when the following contacts closed: door interlocking in MPU carcass sections (K3.1); protection circuit of the energy dosage unit А2.1 (31-37) and frequency transducer А1.1 (37-39). As any door of the MPU carcass is open, position sensors RE1…RE3 switch off the relay K3. Contacts K3 (39-41) interlock the MPU control circuit and turn on light indicator D25. In the operation mode, contacts of FT protection relay (А1.1) and energy dosage unit protection (A2.1) are closed. Protection relay contact break causes MPU operation termination in order to prevent the emergency mode. Light indicators D24, D23 indicate protection actuation in blocks A1 and A2 in the following cases:
- failure in power circuits of blocks;
- ES charging time exceeding 15 seconds, in case of charger elements failure;
- current overload in FT unit during ES charging.
The unit may operate with closed external interlocking circuit connected to terminals (41 – 42) on the connecting block in the control unit. For an interlocking component, electromechanical or contact-free position sensor, installed on the protective cover of the tooling or fencing doors of the magnetic-pulse treatment area may be used. The external interlocking closes the circuit by 24 VDC voltage and below 200 mA current, which then supplies power to relays К5, К6, К7 and set them to operation.
To charge ES, the key S6 shall be closed. Thus key serves for protection against unauthorized high-voltage supplying. Standard operation mode in the primary state is indicated by D20 indicator – “Ready”.
4.3.2 Circuit operation in the single-shot automatic mode
This mode is the basic operation mode of MPU. In this case, the switch S10 “Mode” is set to “Auto” position and shunts S9 button – “Discharge”.
Pressing of S8 button – “Start”, turns on K5 relay, which switches on actuator K2 via contacts K5.1. Contacts K5.2 shunt S8 button “Start” simultaneously for the operation cycle time.
Contacts K2.2 switch on electromagnet EM1 of the residual charge circuitor and prepare the power circuit K1. Electromagnetic circuitor EM1 breaks contacts ЕМ1.1 which shunt high-voltage circuit of the energy store. The contact-free position sensor RE4 located in the operational stroke zone of plunger electromagnet ЕМ1 turns on the relay K4. Relay K4.1 contacts switch on the contactor K1, which then switches on power circuits of high-voltage converter T1 to frequency transducer A1 outlet. Command (48) for FT operation start is given simultaneously.
Transducer A1 supplies the high-voltage converter T1 by current pulses of 1 kHz frequency. At this moment ES starts charging. During ES charging, current pulse duration increases smoothly. Thus, an optimal mode of ES charging and “soft start” of MPU are provided.
The energy store is charged by positive high voltage. Signal proportional to voltage on ES is supplied to the energy setting block A2 via high voltage division devices А3, А4. ES charging voltage is controlled by kilovoltmeter M1 located on the remote control terminal.
When ES charging voltage reaches the given value, previously set with the help of switches in the block A2, relay A2.2 contacts are closed, and the relay K6 is on. Contacts K6.1 disconnect and remove the control signal from FT – ES charging is terminated. Simultaneously, contacts K6.2 switch off the power circuit of the contactor K1 and duplicate T1 power removal from FT. Actuator K1 switching off is delayed from the moment of FT shutdown by the command (48). In this case, power contact wearing in the commutating equipment decreases, because at the moment of contactor K1 turn off current in T1 power circuit was terminated by FT. This increases reliability and security of MPU operation.
Relay K6.1 contacts switch on the relay K7, which supplies the control signal via contacts K7.2 to the start block of arresters A5. Arresters V1 and V2 are actuated by a high-voltage pulse at the moment of capacitors С18, С19 discharge to controlling electrodes of the basic arresters through a supplementary arrester J1. Start pulse generator of the supplementary arrester consists of an optical thyristor ISO1, capacitor С20 and pulse converter T3. At K2 switching on capacitors С18, С19 are preliminarily charged to 6…8 kV and are set to the stand-by mode during charging of ES main capacitors. Capacitors С23, С24 are charged from the power converter T2. By the end of MPU charging-discharging cycle the start unit is disconnected from the power line by contacts K2.3.
When arresters V1 and V2 are actuated, pulse capacitors С5…С17 discharge to the operating inductor L2.
Contacts K7.1 break the power circuit of K5 relay and return MPU to the primary state. Thus, electromagnetic circuitor EM1 is shutdown. Contacts EM1.1 shunt capacitors С5...C17 of ES via ballast resistors R6, R21, removing the residual charge. The single-shot charging-discharging cycle of MPU is thereon ended, and the unit is ready for the following operation cycle.
4.3.3 Manual operation mode
The manual MPU operation mode is basically used at adjustment of the technological process and testing of MPU operation during maintenance. Being kept supplied for long time, longer than 15 s, for high-voltage circuit components (ES capacitors, arresters, ES busbar) reduces MPU operation life. Therefore, during this time it is required to discharge ES of remove high voltage by “Stop” button.
The switch S9 shall be set to “Manual” position. ES begins charging after pressing the button S8 - "Start". In this mode, after relay K6 actuation in the control unit, ES batteries are charged to the voltage preset by A2 unit, and MPU occurs in the stand-by mode. Hence, light indicator D27 – “Charge”, lights on. The command for switching on the relay K7 which controls actuation of arresters V1 and V2 is suppressed by an operator by button S9 – “Discharge”. The operation algorithm of the rest elements of the circuit is similar to the automatic mode.

5.1 Charger
The charger or charging unit (CU) provides charging of pulse capacitors of ES in the range of 5...19.5 kV. CU consists of a frequency transducer A1, single-phase high-voltage converter T1, rectifier D1...D16, and ballast resistor R5. CU rectifier comprises 16 high-voltage diodes 2C202E connected by the bridge circuit. To insulate and cool the rectifier down diodes are located in a reservoir with dielectric oil.
The converter T1 is the oil design, 10 kW power. The nominal voltage of the primary coil is 230 V and the secondary coil – 10 kV, when supplied from the line of industrial frequency of 50 Hz. MPU uses untypical supply of the high-voltage converter: by 1 kHz pulses with 500…600 V voltage from FT A1. In this case, the outlet voltage of the converter is above 20 kV. To limit the actuation current, FT operation mode with pulse-width modulation of output pulses is used. When MPU is started, supply pulses of minimal duration (the pulse ratio 5%) occur at FT outlet. During ES charging, current pulse duration increases smoothly, up to the maximal pulse ratio (50%). Current build-up at ES charging does not exceed 70 A per 2 s. The principal diagram of FT is shown in the drawing 401E.200.400EZ.
AC voltage of the three-phase power line (380 VAC) is converted by rectifying module DN1 to DC voltage on capacitors C8, C21. FT consists of a bridge circuit inverter from modules comprising bridge upper Х1, Х3 and lower Х2, Х4 threshold keys. With the help of modules, DC voltage (500…600 VDC) is converted to pulses with adjustable pulse ratio. The power module comprises two IGBT keys (commutation current 100 A, voltage 1200 V) with built-in intellectual driver PM100DSA120 (Mitsubishi Electric). The load, the high-voltage converter, is connected by outlets Х7/5, Х7/6. The pulse ration control mode is set by PWM controller U1. In case of current overloads, the protection system is actuated by the circuit: ISO2, ISO3, ISO8, ISO9 – Q7 – Q9. In this case, protection relay RE2 contacts shutdown FT terminating MPU charging.
The controlling signal for FT operation start is obtained via optocoupling device ISO14. The current mirror Q2, Q3 forms smoothly growing voltage for controlling the pulse ratio of controller PWM. Each driver of the power keys Х1…Х4 are supplied from autonomous sources +15 V (DC-DC converters) В1, В2, В3, В4. The control circuit of the controller is supplied from the general module (АC-DC converter 220/15 V) В5. To decrease the actuation current, capacitors С8, С21 are charged as follows: initially, via ballast resistors R1, R17, and then 1 s after the actuator K1 is switched on and shunts the resistors.

5.2 Energy store
The energy store consists of 11 pulse capacitors С5…С17, 24 mF capacity each. The capacitors are located in two sections of MPU. These capacitors are united in two blocks with total stored energy of 50 kJ on arresters V1 and V2 with the help of cable busbar.
The cable busbar diagrams ES1, ES2 are shown in the drawings 401E.200.100SB and 401E.200.150SB. To one set of outlets of the capacitor HV wire strands are connected. To another set of outlets of the capacitor braided screens of the cables are connected. To reduce current density and busbar inductance, five strands of coaxial cables RK50-9-11 are connected to each capacitor.
To commutate discharge current, vacuum arresters RVU-47 in MPU are used. Vacuum arresters differ from other types (for instance, air or mercury) by long service life, broad range of operation voltage. They require no periodic maintenance and contain no ecologically unfriendly materials.
The arrester block is shown in the drawing 401E.200.300 SB. Cable busbar from ES1 and ES2 is connected to anode of the corresponding arrester. Arrester cathodes are combined by a flat bus, which is connected to central HV electrode of outlet clamps. Sleeving of coaxial cables from ES capacitors are connected to “ground” electrode and electrically bound to the MPU case.
Ballast resistors R5, R6, R21 limit the charging current and protect the rectifier D1…D16 at polarity change on ES capacitors during oscillatory MPU discharge.
After the end of MPU charging-discharging cycle, electromagnetic circuitor EM1 automatically removes the residual charge from ES via ballast resistors R6, R21.
5.3 Arrester start unit
The unit A5 is designed for HV pulse generation, which initiates breakdown of arresters V1 and V2.
By command “Start” relay K2.3 contacts close, and capacitors С18, С19 are charged to 6…8 kV. By command “Discharge” an auxiliary arrester J1 is actuated, and capacitors С18, С189 are discharged by the circuit R32 (R33) – V1 (V2). On controlling electrodes of the arresters HV pulses of 7 kV amplitude are generated, providing a reliable actuation of the arresters in the operation voltage range for MPU, 1…19 kV.

ATTANTION! Residual voltage, dangerous for life, is preserved on the capacitors С18, С19 during 100 s after MPU shutdown.

5.4 Energy setting block.
The unit A2 provides ES charging to the set voltage, which value id selected by operator depending on technological operation to be performed. The unit represents a functionally complete block located on the control panel of the first section case of MPU.
Circuit diagram of the unit is shown in the drawing 401E.200.500 EZ.
The unit consists of two voltage comparators U1, U4; reference voltage level switches S1…S3; executive relays K1, K2; and protection circuit by the maximum charging time. Comparators U1, U4 monitor the charge voltage for two ES with the help of HV voltage dividers.
The reference signal is supplied to comparators from summing current amplifier U5, U6. Set voltage levels of the charge are formed in a binary-decimal code with the help of weight resistors R45…R62. Using the alternate resistor R60, one may correct the threshold voltage scale. The charging voltage is set by switches S1, S2 within two decades: 1..9; 10...19 kV, and discretely, with 0.5 kV step by switch S3. The set charge voltage is indicated on a digital tableau Н1...H3.
Signals from ES high-voltage dividers proportional to the charge voltage are supplied to comparators inlets. If input voltage equals to the reference voltage, a signal opening transistors Q1, Q7 and Q4, Q6 occurs at the outlet of comparators. The relay K1 is actuated, and the contacts of this relay give a command to stop charging. The circuit D3, D10, C4, C8 eliminates “bouncing” of relay K1 contacts.
If ES charging time is exceeded by more than 15 s, the protection circuit disables the relay K2. Comparator U2 represents a timer, which is actuated by “Start” command and and disabled, when comparators U1, U4 reach the preset voltage level. In case of failure of MPU charging unit elements, ES charging time exceeds the allowable duration of 15 s, and protection circuit terminates MPU charging by contacts K2.1.

5.5 MPU circuit element supply
The CE is supplied by the three-phase 380...400 VAC line via protective automatic breaker S2 designed for 63 A. MPU is supplied via copper or aluminum wires with the section 10 mm2 or more and 16 mm2 or more, respectively, connected to inlet terminals mounted in the first section of MPU case.
At the moment of ES discharge, at the outlet of frequency transducer A1 pulses with 500…600 V voltage and 1 kHz frequency are formed. At HV CU elements the maximal voltage reaches 20...25 kVDC. On ES capacitors the charge voltage varies in the range of 1...19.5 kV.
The arrester start unit is supplied by 220...230 VAC via protective automatic breaker S11, designed for 25 A current. Start unit elements possess high voltage of 7…8 kV.
The relay control circuit is supplied from AC-DC converter A6 by 24 VDC. Actuators K1, K2 and electromagnetic circuitor EM1 are supplied by 220 VAC via protective breaker S4 designed for 10 A current.
Energy setting unit A3 components are supplied by 24 VDC and from built-in power modules DC/DC +/-15 V.
5.6 Outlet terminal kit
The inductor is connected to MPU outlet terminals directly or via a transition cable. The outlet terminal kit is shown in the drawing 401E.200/300 SB.
Outlet terminals are located on the second section panel, on which transition cable clamps or tooling with the inductor may be erected. Flat outlets of the inductor are inserted to the kit so that one end of the outlets is directed to central HV electrode, and another end - to grounded electrode, and is squeezed up by a screw. An insulating liner sized as follows shall be placed between inductor outlets:
- the distance between contact surface of the inductor buses (with respect to liner thickness) is 24 +/- 2 mm;
- the distance between inductor outlets by the insulation surface (the surface discharge path by insulation), as calculated from the charge voltage, is 2 kV/mm or higher.
The transition elongating cable for inductor operation remote from MPU shall be of the minimal inductance. To reduce losses in the transition cable, it is made of 5-10 coaxial radio cables, connected in parallel. Cables shall have a multi-wire central strand of a large section, RK50-9-11, RK50-11-13, for example.
When connecting the transition cable, observe polarity of cable outlets and MPU!
HV cable outlet, to which central strands of coaxial cables are connected, shall be attached to the central electrode (marked by a special sign ). “Grounding” cable outlet, to which braided screens are connected, shall be attached to the grounded electrode (marked by the ground sign ).

6.1 Requirements to MPU placement
Compartment where MPU is located shall meet the requirements from sections 1.2, 1.3 of this technical description and “Safety instructions operation of MPU-50”. MPU may be placed on a separate site or in general workshop. In the second case, MPU site shall be fenced. An approximate scheme of the MPU site is shown in Fig. 3.

Fig. 3. MPU-50 site scheme

The distance from MPU power unit to walls, fencings and other objects is determined by the servicing zone, which should be greater than 0.8 m by the perimeter. At the operation site not strong shaking or vibration shall be observed.
At the MPU site a ground grid shall be mounted or connection to the workshop ground grid shall be provided.
MPU is supplied via a distribution box with the nominal current 63 A or higher. On the MPU site, 220 VAC receptacles for instrumentation and electric tools for performing commissioning and maintenance are located.

6.2 MPU erection
Before MPU erection remove covering from all cases of every section. Check condition of the contact surface of cable busbar in the arrester, on outlet clamps and pulse capacitors. Remove corroded material and soot from the contact surface using a fine abrasive tool or a riffler. Remove protective bridges from high-voltage outlets of capacitors, clean and remove fat from the insulator surface of pulse capacitors and cable busbar using a sponge moistened with alcohol.
Erection of the components shall be started from the charging unit section and arrester block. In the charging unit section high-voltage charge and start unit power supply converters are installed. Pulse capacitors are erected in the arrester section. Five coaxial busbar cables are connected to each capacitor. Cables are fixed in a strap using strainers. The bending radius of cables is 50 mm or more.
Similarly, in the third ES section capacitors are installed and cable busbar is erected. Cables connecting arresters and capacitors laid uniformly, avoiding crossing or twisting, as well as touching of capacitor high-voltage outlets and CU by protective insulation of the cable.
After capacitor erection is complete, ES is to be connected: ballast resistors, charging unit; control wires of the arrester start unit are connected.
Install contact-free position sensors for case door interlocking. Adjust gaps between active surface of the sensor and the case door. The gap shall not exceed 2 mm.
Prior to commissioning, MPU shall be tested for the following:
- conditions and reliability of electric connections between cable busbar and terminal blocks located on the control panel of the power unit and inside the control panel;
- the absence of surface defects and HV conductor insulation damages in the arrester, outlet clamps, and residual charge circuitor;
- reliability of contact closing and stroke of the plunger electromagnet EM1 (this test shall be performed manually, with power supply off). Check the gap value between the position sensor and electromagnet metal flag in the circuitor EM1 (less than 2 mm).
Connect the MPU case and the control panel to the ground grid by copper conductors 10 mm2 and 4 mm2, respectively. MPU ground grip resistance is below 4 Ohms.
The control panel is connected to the power unit by an umbilical cable. Excessive bending of the control cable is not allowed, because bending of less than 200 mm by radius may cause cable strand break. A place for control panel installation is chosen with respect to ease of observation for tooling and provision of operator safety during MPU operation.
MPU power supply from the distribution box is performed by a four-strand cable having a zero wire, in rubber or PVC insulation. Current-conducting strand section shall be not less than 10 mm2 for copper and 16 mm2 for aluminum.
External interlocking circuits of the MPU site (on the entrance door, for instance) are connected to the terminal block (contacts 41-42) in the charging unit section by a cable with rubber of PVC insulation and strand section not less than 0.75 mm2. If external interlocking is absent, a bridge between contacts 41-42 is installed.
The discharge stick shall be connected to the ground terminal on MPU case permanently. The stick is installed nearby the carcass doors, in a place comfortable for the user. Grounding wire of the stick is made fro flexible multi-strand copper conductors with the section of 10…25 mm2.

7.1 Only personnel acquainted with TD and Safety instruction for operation of magnetic-pulse unit MPU-50, and trained for the unit operation is allowed for controlling, maintenance and repair of MPU. MPU produces voltage up to 20 kV, which is dangerous for life.
7.2 Before starting MPU operation, the presence and state of protective means at the site are checked (insulating gloves, pads, discharge stick, etc.). Prior to operation, the state of grounding devices is checked. The discharge stick shall be permanently connected to MPU power unit!
7.3 MPU operation is prohibited, as parts of the power unit and the control panel are open. MPU operation and adjustment with switched off load (inductor) or operation with the inductor without stock material and tooling is prohibited. Protective cover is removed and the doors are open, as required only.
7.4 MPU operation in the short circuit mode is allowed (a copper or aluminum bridge with section over 100 mm2 is installed to the clamp) for the purpose of checking functioning and performing proof tests on MPU. Maximal charge voltage at short-circuit is not less than 7 kV.
7.5 Do not touch high-voltage components right during 100 s after MPU shutdown. MPU scheduled maintenance, inspection and repair shall be performed after switching off the supply voltage and removing residual voltage from EA batteries and the strat unit using the discharge stick.
7.6 All repair and prophylactic works on MPU electric installations shall be performed by a crew of 2 persons or more.
7.7 Whenever possible, perform works in a dry compartment with insulating floor cover or use insulating material at the operator working place. Avoid accidental contacting with any parts of the equipment (including tooling) at the moment of EA charging and discharging.

Location of control elements on the MPU control panel is shown in Fig. 4.

Fig. 4. MPU-50 control panel (section 1)

On the front panel of the MPU charging unit section the following elements are located:
- inlet power switch (S1);
- “Power” (LP2) and “Charge” (LP5) indicators and protection indicators: energy dosage block – “EDB”, frequency transducer – “FT”, and door interlocking of MPU case sections – “Doors”.
- “Charge voltage” switch of the energy dosage block (S1…S3) sets the charge voltage in the range of 1 – 19.5 kV and is changed discretely, with 0.5 kV step. Table of charging voltage and stored energy voltage dependencies at synchronous operation of two ES is located on the control panel.
- digital tableau (H1…H3) indicates the set ES charging voltage.
Location of control elements on the MPU on remote terminal panel is shown in Fig. 5.

Fig. 5. MPU-50 remote control terminal

On the remote terminal panel buttons “Start” (S8), “Discharge” (S9), “Stop” (S7), switches “Mode” (S10), “Key” (S6), and the charge voltage indicator (M1) are located.
In any operation mode, pressing of the button “Start” gives a command for ES charging.
In the manual mode, pressing of the button “Discharge” the operator gives a command for MPU discharge.
Pressing of “Stop” button terminates MPU operation in all modes and removes the residual charge from ES elements. “Stop” button is mechanically interlocked to avoid accidental pressing. To restore the control scheme to service, “Stop” button shall be unlocked by turning it in the arrow direction.
The “Key” switch interlocks the control circuit and prevents unauthorized switching on high voltage.
The pointer indicator shows current value of ES charge voltage.
"Charge” signalling lamp lights on, when ES charge reaches the desired level (in the manual mode).
“Ready” Signalling lamp indicates MPU readiness for operation.
“Mode” switch sets the desired operation mode: “M” – manual or “A” – automatic.

9.1 Prior to operation, check visually the state of outlet terminals, inductor, tooling, grounding wires, and discharge stick for the absence of mechanical damages. In the case of burn-contact coupling burns-on and contamination of high-voltage insulators, clean and degrease the surface with a sponge wetted with alcohol.
9.2 Using the “Mode” switch on the remote control terminal, set manual or automatic operation mode. Set external interlocking of the MPU site to service.
9.3 Connect MPU to power line by “Power” switch located on the front panel of the case. Signalling indicator “Power” and digital indicators on the control panel light on. Protection system indicators “EDB”, “FT”, “Doors” located on the MPU panel shall not light on.
9.4 Using “charge voltage” switches set the required voltage by the digital tableau.
9.5 During charging and discharging operative control of MPU is performed from the remote control terminal.
9.6 Manual operation mode.
Make sure that people are absent in the operation inductor zone and MPU outlet terminals. Unlock the control system by the “Key” switch. Hence, the indicator “Ready” shall light on.
Pressing of “Start” button turns on ES charging mode. “Charge voltage” pointer indicator shows current value of the charge voltage, which smoothly increases to the desired level. When the preset voltage is reached, charging is stopped and “Charge” indicator lights on. Discharging is initiated by pressing “Discharge” button. The command for discharge is given by the operator without delay (2-3 seconds as a maximum), because keeping ES charged for long by high voltage reduces MPU service life.
After discharge, make sure by “Charge voltage” indicator, that the residual charge on the capacitors is absent.
Switch the control system off by the “Key” switch and shutdown MPU. This is the end of the manual mode operation.
9.7 Operation in the automatic mode.
After pressing “Start” button MPU is automatically charged to the preset energy level and then single-shot discharged. After discharge the MPU control system returns to the primary state.
9.8 If immediate termination of charging and removal of high voltage from ES elements without discharge to the inductor is required, press “Stop” button. Hence, ES will discharge to the ballast resistor, and MPU will be ready for repeated operation cycle.
If any deviation from the standard mode are observed (specific noise of electric arc during charging, visible sparking in the boxes, etc.), press “Stop” button, shut the unit down and repair the failures.

10.1 Maintenance of the unit is of planned and preventive type and consists of a set of mandatory works performed for the purpose of providing reliable MPU operation, prevention of faults and malfunctions.
10.2 When performing MPU maintenance, strictly conform to the safety rules of high voltage units operation and requirements of Safety instruction for MPU-50 operation, 401E.136.000 SI.
10.3 MPU maintenance includes:
- external inspection;
- regular checkup of the state and workability of MPU parts;
- performance of prophylactic operations;
- testing and diagnostics.
Testing and diagnostics are performed after the warranty period end and after 50,000 pulses passed.
10.4 External inspection of MPU is combined with other kinds of maintenance and is performed daily, prior to operation.
Fixation of inductor outlets and tooling is checked. The state of MPU control organs, protective means, connecting cables and grounding for absence of mechanical damages are checked.
10.5 Once a month prophylactic maintenance is performed. Conditions and workability of MPU parts in high voltage absence on ES elements are checked. For this purpose, power circuit of automatic switch S4 control unit is shutdown. Turn on lighting in MPU case sections using automatic switch S5.
Perform external inspection of insulators: pulse capacitors, converters T1 and T2 in the charging unit, arresters, cable busbar, and ballast resistors for the absence of damages and traces of electric discharges and arcs.
The absence of capacitor corpse blistering and cracks in the corpse and insulators with insulating oil leaks.
The state of arrester block, outlet terminals, and mobile part of circuitor electromagnet EM1 is checked. The state of circuitor contacts and ease of manual actuation of the movable part without switching on power supply is checked. A short-term seizure of the mobile system, suspension or switching off delay by more than 1 second is not allowed.
Dust from high-voltage parts insulators in the arrester block, residual charge circuitor, charging unit, start unit, and ballast resistors is removed. The insulation surface shall be cleaned with a sponge, wetted in ethyl alcohol.
The state of MPU and technological equipment grounding conductors is checked. If more than 50% of conductor section is damaged, the grounding element shall be replaced.
Discharge stick for the absence of damages and contamination on the insulating part is checked. Wholeness of the stick discharge chain resistance is checked using an ohmmeter. Dropping resistor value shall be not less than 50 Ohms.
10.6 Once a year prophylactic maintenance of pulse capacitors, cable busbar, and outlet terminals is performed.
Dust from insulators of pulse capacitors is removed, and HV busbar cable collectors are blown through with compressed air.
The state of MPU outlet terminal elements is checked. The checkup is performed after dismantling from the power unit panel. Outlet terminals are externally inspected for the absence of damages. The insulating parts shall have no cracks and traces of electric breakdown. Electric contact surfaces of current conducting buses are cleaned from corrosion and soot. Prior to assembling, insulation parts are cleaned from dust and wipes by a sponge wetted by ethyl alcohol.
10.7 Once per three years or after 50,000 pulses passed, the kilovoltmeter and energy setting block are checked.
Kilovoltmeter and accuracy of energy setting block actuation are checked at working charge voltages, not less than in three points of the range from 1 to 10 kV.
Prior to checkup, the inductor calculated for the highest discharge energy shall be connected to MPU outlet terminals. Select the manual operation mode. Connect an etalon kilovoltmeter with the measurement range not less that 25 kV and accuracy of 2.5% to ES capacitors. Measurements were performed during 2-5 s after energy setting block actuation, with regard to inertness of the measurement system and charge voltage leaks in ES.
The results are considered satisfactory, if indications of the pointer indicator on the control panel and ES capacitors voltage measured by etalon kilovoltmeter coincide with the preset level with ±5% accuracy. If the charge voltage deviates by more than allowed, the voltage scale may be adjusted by variable resistors, installed in the energy setting block and on the kilovoltmeter board in the remote control terminal.
10.8 Parameters of the discharge circuit are controlled after replacement of pulse capacitors and vacuum arrester in ES. They may be controlled at MPU discharge in the short-circuit mode on outlet terminals. On the terminals a bridge is installed, which closes MPU outlets. The bridge section is not less than 100 mm2, it is made from copper or aluminum.
The discharge circuit parameters are determined from the discharge current oscillogram. Maximal ES voltage at MPU operation in the short-circuit mode shall not exceed 7 kV. The discharge current is controlled using a contact-free pulse current sensor with the working frequency of discharge not less than 40 kHz and maximal amplitude of pulse current not less than 100 kA. The current sensor is installed on the bridge of outlet terminals via insulating liners so that measuring coil of the sensor wraps the bridge with current to be measured.
From current oscilloscope record the frequency (period) of discharge current and amplitudes of the first and the third half-periods are determined. To get data, a storage oscilloscope is used, to which the current sensor is connected. The maximal amplitude of discharge current is calculated by the formula:
Imax = 2π · f · U0 · CΣ · e (-k / 4) (1)
where f is the discharge current frequency according to oscilloscope record, f = 1/Т;
T is the oscillation period according to the oscilloscope record;
U0 is the ES charge voltage;
CΣ is total capacity of ES capacitors;
k is the damping factor calculated by the formula:
k =ln(I 1 / I 3) (2)
where I 1 is peak-to-peak amplitude of the first half-period of current oscillations;
I 3 is peak-to-peak amplitude of the third half-period.

Fig. 6. The example of discharge current oscilloscope record.

Measured parameters (discharge frequency, current amplitude) shall not differ from values obtained in the control tests of MPU by more that 10%. If discharge parameters deviate from the norm (discharge current frequency and amplitude), capacity of ES capacitors and cable busbar shall be checked for strand breaks in some cables.
Capacity for pulse capacitors is measured with disconnected busbar cables and 1 kHz measurement frequency. The measuring device accuracy shall not exceed 2%. Measurement results on capacity are drawn up as a record also showing serial number of every capacitor. If during operation capacity increases by more than 20%, such capacitor shall be disconnected and replaced. If capacity decreases by more than 20%, the possibility of such capacitor is determined regarding correction of total capacity for the battery and acceptability of stored energy reduction for implementation of particular technological operations.

11.1 MPU is allowed for transportation disassembled only: the power unit sections are disconnected and transported separately; pulse capacitors are dismantled and removed from the sections; the charging unit converter is dismantled and transported separately.
11.2 Loading and unloading of power unit sections by crane or fork lift is allowed only for dismantled parts by lifting screws mounted to the case cover.
11.3 Pulse capacitors are transported either by holds located on the housing or by fork lift by the housing bottom, providing stable verticality. During transportation and storage, high-voltage outlet of capacitors shall be short-circuited by wire bridges 0.5-1.5 mm2 in section.
11.4 The converter shall be transported by crane held by arms on the side wall of the housing or by a fork lift providing stable verticality; the tilt shall not exceed 30°.
Transportation of power unit section with control components and cable busbar assembled with arresters. Connector wires and busbar cables shall be bundled and reliably fixed.
11.6 When stored for long, MPU shall be located in closed compartment with relative humidity below 98% and ambient air temperature from +5 to +40°C. The power unit housing shall be protected from dust penetration. Acid, alkali and other aggressive vapors in ambient air are not allowed.

12.1 When the switch “Key” is on, indicator “Ready” doe not light on and MPU charging remains off:
- Check “Stop” button locking by turning it in the arrow direction;
- if “Door” diode lights on, make sure that all doors of the housing are closed, then check and adjust gaps between position sensors and the door;
- check the state of frequency transducer; if “FT” diode lights on, check operation of automatic switcher S2, restore FT protection system by pressing “Reset” button, if red indicator lights on in the FT window;
- If diode “EDB” lights on, check the state of energy dosage block A2; check net fuse in the block and voltage +24 V at the outlet of the feeding module A6.
12.2 ES does not charge after pressing "Start" button:
- check wholeness of ballast resistors and reliable actuation of electromagnetic circuitor EM1 (see par. 10.5);
- check the rectifier D1...D16; the test is performed under ohmmeter voltage above 30 V and direct current limited to 100 mA;
- check for short-circuiting in the high-voltage cable busbar and pulse capacitors; checked by megaohmmeter at 1-2.5 kVDC.
12.3 If arresters are not actuated, remove ES charge by “Stop” button, check connection of inductor and transition cable to MPU outlet terminals, and make sure that protection is correct – light indicators do not light on.
If arresters fail repeatedly:
- shutdown MPU, open the carcass door, check for the absence of residual charge on ES capacitors and the start unit using the discharge stick;
- check the state of automatic switch S11 supplying power to the start unit.
- check if neon indicator on the arrester start unit board (the arrester section) lights on. Voltage between thyristor ISO1 anode and cathode shall be 500 V or higher.
- if traces of breakdowns or electric discharges are observed on the insulator surface, clean and degrease the insulator surface of converter T3, capacitors C18, C19 in the start unit;
12.4 In the case of spontaneous actuation of arresters prior to reaching the given voltage, check and maintain arresters and the start unit. If self-breakdowns repeat after maintenance, train arresters.
12.5 Arrester training
After transportation and long storage of arresters, training in the operation mode prior to commissioning is required. Training consists of charge voltage gradual increase from 5-10 kV to the operation level, 1-3 kV stepwise. Training requires the manual operation mode.
Install an inductor designed for excessive discharge energy at which self-breakdowns were observed, to the outlet terminals. Set the minimal charge. Charge ES and wait for 5-10 s, then press “Discharge” button to discharge ES. Make 3-5 repeats at this level of energy. The interval between charge-discharge cycles shall be 10 s or more. Gradually (by steps) increasing the charge voltage, reach stable operation of MPU. The criterion to stop training at each step is the absence of spontaneous breakdowns in the arrester. When training, check the inductor and preform heating rate. If the inductor housing is heated over 50°C, make a break to cool down the inductor system.


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1.1 Under the terms of electrical safety, the magnetic-pulse unit (MPU) is related to high-voltage electrical installations, over 1000 V.
1.2 This instruction is applied to the operating MPU. The following unit is considered operating, which is fully alive or which may be supplied at any moment by turning on the switching equipment.
1.3 MPU may be operated according to the rules developed in customer’s branch. The branch rules shall not be in conflict with this instruction.
1.4 The required safety documentation shall be present at the working place. It shall be composed in accordance with the requirements of this instruction, basing on standard documents and directives of the plant with regard to local conditions. Documents on electrical safety shall be signed by a person responsible for power facilities and approved by technical director of the organization.
1.5 The sets of duty regulations and safety instructions shall exist at every working place of the MPU site. The list of such instructions is approved by a person responsible for labor safety for the organization.
Duty regulations shall include the following:
- the list of MPU operating instructions, directives and charts, knowledge of which is mandatory for the personnel maintaining the MPU site;
- personnel’s rights, liabilities and responsibility;
- mutual relations with line management, subordinates and other persons related to the work at the MPU site.
2.1 The personnel only trained for maintaining MPU and instructed on safety are authorized for MPU operation is allowed to operate MPU. Once per year, safety knowledge of MPU maintenance personnel is tested on a periodic basis by an enterprise committee.
For MPU operating, the personnel specially chosen and approved by an enterprise executive order is responsible.
2.2 As operated in the automatic mode according to technological programme developed beforehand, MPU may be operated by a single operator.
2.3 Scheduled operations, repair and adjustment of MPU are implemented by trained electrotechnical personnel in crews of 2 persons or more or by an operator and a person responsible for the works. The person responsible for works shall have special qualification on electrical safety for unrestricted work on units with voltage above 1000 V.
2.4 Safety tests shall be performed by qualified committees of the enterprise, where the personnel maintaining MPU is employed. Every worker is examined individually, the results of tests are recorded to a log, and a quiz certificate with electrical safety group assignment is issued.
3.1 The unit is located in a dry, heated compartment containing no aggressive vapors and gases, which may cause corrosion and deterioration of dielectric properties of the insulation, current-conducting dust, where a possibility of dangerously explosive and fire hazard mixtures is eliminated.
3.2 MPU-50U may be operated both in a separate compartment and in a general workshop. In the second case, MPU site shall be fenced. The fencing shall be 1.8 m or higher. The fencing doors shall be outward-opening and have locks.
3.3 On the MPU site, a ground grid shall be mounted or possible connection to the workshop ground grid shall be provided. Ground grip resistance is below 4 Ohms. The power unit and the wiring table are screwed to the ground grid by a conductor 10 mm2 or greater. Grounding conductor section for MPU remote control panel shall be 4 mm2 or greater.
3.4 Discharge stick is connected to the grounding bolt by flexible copper strands having total section of 6 mm2 or greater.
The stick consists of the working part with a dropping resistor, which shall be reliably fixed to the insulating part end, a handle and a grounding resistor connected to the ground grid. Minimal size is 1000 mm for the insulating part and 400 mm for the handle. Resistance of the dropping resistor is less 100 Ohm with the power less 100 W.
3.5 The unit is supplied via a distribution box from a three-phase 380…400 VAC line with minimal current 63 A or higher. MPU is supplied via a four-wire of 10 mm2 or greater section for copper cable and 16 mm2 for aluminum cable.
3.6 The distance from MPU to the walls, fencings and other objects is determined by the servicing zone, which should be greater than 0.8 m by the perimeter.
3.7 The MPU site shall include a stand to the fore showing operation instructions, maintenance guidelines and safe operation rules.
3.8 The MPU site shall be equipped with protective means:
- extinguishers, not less than 1 piece;
- special discharge stick for voltage of 35 kV or higher (insulating stick with a dropping resistor) – 1 piece;
- dielectric gloves - 1 pair;
- dielectric pads - 2 pieces.
All protective means shall be test stamped and stored on the fore.
3.9 In the case of destruction, to protect personnel from flying apart fragments of the inductor or tooling destroyed during discharge, MPU control panel is located in a separate cabin or behind protective screen from high-impact glass.
3.10 MPU site doors shall be equipped with a placard or warning lights “HOT WIRE!” (“HIGH VOLTAGE – DANGEROUS!”), which is turned on during MPU operation.
3.11 To eliminate accidental touching of high-voltage parts of the equipment during operation or unauthorized access to the operation doors of the MPU site, the operator cabin and protective fencing of the tooling are equipped with electric interlocking preventing from turning on high voltage at MPU. Electric interlocking may represent electromechanical terminal switches or 24 VDC contact-free electronic position sensors.
3.12 Maximum permissible level (MPL) of pulse EMF at the operator place recommended by the committee of the Ministry of Health shall not exceed 100 A/m for 1 to 30 kHz frequency. Therefore, MPU control panel is located 2 m or more from the power unit and the inductor.
3.13 MPU site may have both combined and artificial lighting. Normalized illumination for general lighting system (lamps are disposed uniformly, at the ceiling of compartment) is 300 luces.
3.14 At the MPU site, broadband noise of low intensity and impulse noise of high intensity shorter than 0.01 s are detected.
The equivalent sound level of impulse noise at discharge shall not exceed 85 dBA.
Personnel working in the zones with the sound level above 85 dBA shall apply individual protection means, protective head sets, for example. As MPU is operated, noise may be reduced by corresponding design of the equipment or inductor zone shielding by special covers. As the sound impulse at discharge appears, and the personnel shall be warned about it, the MPU site is equipped with a warning horn.
4.1 At the MPU site, the following is shown:
MPU basic diagram indicating input apparatus number in the supplying distribution board;
- special stick for control discharge of batteries;
- fire-fighting means;
- working instruction for safe operation put up at clear sight near the unit.
4.2 MPU operation is prohibited, as high-voltage power unit parts are open or the inductor is off.
4.3 Persons not authorized as operative or technical personal and in the absence of authorized personnel are not permitted at the MPU site during its operation.
4.4 MPU adjustment of tooling, maintenance, examinations and repair are the works performed after MPU switching off and removal of electric residual from batteries.
4.5 Before carrying out any operations, which may cause touching high-voltage parts of the equipment, make sure, by external examination that the discharge contactor of electrical residue chain is in order. Make a control discharge of batteries independently of indications that MPU is off. Indicators and kilovoltmeter are only auxiliary means, which indications shall not induce any decision about voltage elimination. Indication of warning devices about voltage supply is the absolute sign for impermissible approach to high-voltage parts of the equipment. In this case, MPU shall be disconnected from the distribution box. The residual charge of batteries is removed 3 min after disconnection via load resistor (terminal R) in the discharge stick.
4.6 Batteries are subject to control discharge by special discharge stick for 35 kV or higher.
When discharging batteries by the discharge stick, insulating gloves shall be used. The operator shall stay on a dielectric pad and shall not touch the grounding wire.
4.7 During examinations, scheduled operations and adjustment the following is checked:
- the absence of dust, dirt, foreign objects, and cracks on insulators;
- the absence of battery corpse blistering and oil leaks on batteries and the charger. The presence of oil spots (sweating) is not the reason for taking batteries and the charger out of service. Such equipment shall be taken under the supervision;
- working order of the discharge contactor of electrical residue circuit and ballast resistors;
- working order of current-conducting buses, grounding wire, discharge and batteries cable bus arrangement.
4.8 Extra examinations of MPU are performed in the case of sparking, ambient noise in batteries, discharger and the start unit.
4.9 MPU operation is prohibited in the case of:
- battery wall blistering;
- oil trickle from batteries and the charger case;
- damage of battery, charger, discharger and MPU outlet terminal insulators.
4.10 If more than 50% of conductor section is damaged, the grounding unit shall be replaced.
4.11 Adjustment during MPU tests without removal of voltage is allowed, if accidental approach of working personnel and tools used to current conducting parts by 0.6 m or shorter is eliminated. Works on current-conducting part and near them without removal of voltage shall be performed using protective means. The work shall be performed by two persons or more.
4.12 As works are performed with removal of voltage, the following measures shall be implemented respectively:
- necessary shutdowns shall be made and measures preventing voltage application to the place of work due to a mistake or spontaneous switching of the equipment shall be undertaken;
- inhibiting placards are put up on the manual control drives;
- switch off automatic breaker in the charger power circuit;
- remove electric residue from energy store batteries and the start unit.
4.13 MPU testing with high voltage is performed by a crew of 2 persons or more.
The testing place and connecting wires at high potential shall be fenced. At the test site personnel shall be exposed, who will oversee for observation of safety rules. Screens, barriers, ropes with suspended placards “STOP! HIGH VOLTAGE” can be used as fencing.
Prior to initiation of tests the works supervisor shall:
- check if all crew members are at designated places and remove unauthorized persons;
- warn the crew about voltage supply. After making sure that the warning was heard by all members of the crew, supply voltage to MPU.
Measurements shall be performed in dielectric gloves, standing on an insulating base. During measurements it is prohibited to touch devices and connecting wires. At the end of tests MPU shall be shutdown and electrical residue shall be removed by the discharg.

A sample of standard safety instruction for MPU operator

Safety instruction for operation of magnetic-pulse unit MPU-50U for operating personnel.


1.1 Personnel acquainted with the unit arrangement, trained for MPU maintenance rules and certified by the committee for electrical safety is allowed for MPU operation. For MPU operating, the personnel specially chosen and approved by an enterprise executive order is responsible.
1.2 As operated in the automatic mode according to a technological programme developed beforehand, MPU may be operated by a single operator. Mastering of a new technology for detail preparation is performed by a crew of 2 persons or more, with participation of a technologist or an electrician.
1.3 During charging and discharging MPU obtains voltage up to 20 kV, which is life-threatening. To protect personnel from high voltage and flying apart fragments of destroyed inductor or tooling, MPU is controlled from the panel located in a separate cabin with high-impact glass.
1.4 To eliminate accidental touching high-voltage parts of the equipment during operation or unauthorized access to the operation zone, the doors of MPU site and the operator cabin are equipped with electric interlocking, which prevents from switching on high voltage at MPU and warning lights, indicating “Danger! High voltage”.
1.5 Persons not authorized as operative personnel without permission and in the absence of authorized personnel are not allowed at the MPU site during operation.
1.6 Adjustment of tooling, maintenance, inspections and switching of inductor and transition cable are works performed after MPU switching off.
1.7 At the MPU site, the following protective means shall always be present: extinguishers, discharge stick with a dropping resistor, dielectric pads and gloves, protective head sets.

2.Preparation for works.

2.1 Before starting MPU operation, the presence and state of protective means at the site are checked. The discharge stick shall be permanently connected to MPU power unit.
Prior to operation, the wholeness of grounding conductors of the MPU case and the control panel is checked.
2.2 Check visually the state of MPU outlet terminals, inductor, tooling, transition cable, grounding wires, and discharge stick for absence of mechanical damages. In the case of burn-contact coupling burns-on and contamination of high-voltage insulators, clean and degrease the surface with a sponge wetted with alcohol.
2.3 Set and fix the inductor to MPU outlet terminals or connect by the transition cable. When connecting the transition cable, observe polarity of high-voltage strands!
One end of the cable is fixed to MPU outlet terminals, and another end is set on arms of the tooling in order to eliminate vibration of the cable at discharge.
2.4 The inductor and transition cable shall be connected and disconnected only, when MPU is shutdown!

3.MPU operation.

    MPU operation modes shall be set at switching on the supply by “Power” switch and turned off key contact “Key”. At breaks in the operation, the key contact shall be turned off, and the operator shall hold it in order to eliminate accidental or unauthorized supply of high voltage to MPU.

3.2 MPU operation is prohibited, as parts of the power unit and the control panel are open. Operation with removed hull plating and open doors of MPU shall be performed as needed, at testing and adjustment of electric equipment by a crew of electricians.
MPU operation and adjustment with switched off load (inductor) or operation with the inductor without stock material and tooling is prohibited.

    Before switching on the charge, mare sure that the control system is ready for operation. In this case, the indicator “Ready” shall light on.

In the case of failure, one of red indicators of the protection system on the charging unit section panel (“BDE”, “PH”, “Doors”) lights on. In this case MPU shall be disconnected from power supply and operation of the protection system of MPU control unit shall be checked, if:

“Door” indicator lights on, check that the carcass doors are closed;

“PH” indicator lights on, switch off MPU and 10…15 s after that turn off and then on the automatic switch S2;

“BDE” indicator lights on, turn off and 10…15 s after turn on the automatic switch S11;

    In the case of discharge, the inductor and tooling shall be located 2 m or farer from the control panel.

    If unauthorized persons appear in operating unit’s or tooling zone at the moment of discharge, stop MPU operation by “Stop” button.

3.7 Whenever possible, perform works in a dry compartment with insulating floor cover or use insulating material at the operator working place. Avoid accidental contacting with any parts of the equipment (including tooling) at the moment of EA charging and discharging.

    According to well-proven technological programme discharges are performed automatically. Development of a new technology and execution of proof-testing may be performed in the manual operation mode.

Long MPU occurrence with charging voltage (over 15 s) between charging completion and discharge is prohibited.

    If no discharge happens after obtaining the charging voltage, remove high voltage from MPU by pressing "Stop” button and check the absence of electrical residue by kilovoltmeter.

If an electrical residue is present on the energy accumulator, after pressing “Stop” button carry out the following:

disconnect MPU from the power line;

120…150 s after disconnecting open the carcass section doors, not touching high-voltage MPU components;

remove residual voltage from energy accumulators using the discharge stick. When operating the stick, the operator shall stand on a dielectric pad and hold the stick by insulating gloves!

stop further MPU operation and call for electricians for troubleshooting service.

    If at the moment of discharge heavy sparking occurs in MPU, inductor and transition cable outlet clamps, shutdown MPU and check contact joints. To eliminate sparking, rub contact surfaces or put a soft copper foil 0.5…0.8 vv thick between the contacts. A weak unrepeated sparking is eliminated by tightening the clamps. It disappears during further discharges due to self-compaction of the contact joint.

    When sparking or indicative noise of electric discharges inside MPU case during charging, MPU operation is prohibited. In this case, stop charging by pressing “Stop” button, disconnect PMU from the source line, and call for electricians for troubleshooting service.

4.Completion of works.

4.1 After completion of works turn off the control system by “Key” switch and remove the key, avoiding unauthorized switching MPU on.

    Switch off MPU supply by input switch in the charging unit section.

4.3 Do not touch high-voltage components right after MPU shutdown, during 100 s. MPU scheduled maintenance, inspection and repair shall be performed after switching off the supply voltage and removing residual voltage from EA batteries and the start unit using the discharge stick.

New model

New model for magnetic-pulse treatment materials. All pulse parameters are stored in the archive and can be used to create passport operations. Multilevel protection system against the current. Installing manipulator possible to automate the process.


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