Kemppi KEMPACT 253R User manual

Kemppi Oy
SERVICE MANUAL
KEMPACT RA
181A
251R/251A
253R/253A
323R/323A
253MV/323MV

SERVICE MANUAL
KEMPACT RA_V_1.2
1 (4 )
Kemppi Oy
CONTENTS
1. PARTS OF MACHINE................................................................................................................................................................................ 3
2. TECHNICAL INFORMATION ..................................................................................................................................................................... 5
2.1. Technical data ................................................................................................................................................................................ 5
2.2. Main circuit diagrams ..................................................................................................................................................................... 9
3.1. Main components ........................................................................................................................................................................ 13
3.1.1. Terminal block X 1 ............................................................................................................................................................. 13
3.1.2. Varistors R 1 ...................................................................................................................................................................... 13
3.1.3. Main switch S 1 ................................................................................................................................................................. 13
3.1.4. Terminal block X 9 ............................................................................................................................................................. 13
3.1.6. Test connector X 6 ............................................................................................................................................................ 13
3.1.7. Auxliary transformer T 2 and rectifier bridge G 3 .......................................................................................................... 13
3.1.8. Control card A 1 ................................................................................................................................................................ 13
3.1.8.1. Auxiliary power supply ................................................................................................................................................ 13
3.1.8.2. Microcontroller ............................................................................................................................................................ 13
3.1.8.3. Motor control .............................................................................................................................................................. 13
3.1.8.4. PWM ............................................................................................................................................................................ 14
3.1.9. Fans M 1, M 2 ................................................................................................................................................................ 14
3.1.1 . Solenoid valve Y 1 ........................................................................................................................................................... 14
3.1.11. Wire feed motor M 3 ...................................................................................................................................................... 14
3.1.12. Brights led card P 2 ......................................................................................................................................................... 14
3.1.13. Panel card P 1 ................................................................................................................................................................. 14
3.1.14. Main transformer T 1 ...................................................................................................................................................... 14
3.1.15. Secondary rectifier card Z 2 ............................................................................................................................................ 14
3.1.16. Secondary choke L 1 ....................................................................................................................................................... 15
3.1.17. Output RFI filter C 1, C 2 .............................................................................................................................................. 15
3.1.18. Output terminal X 4 ........................................................................................................................................................ 15
3.1.19. Euro connector X 5.......................................................................................................................................................... 15
3.2. Main circuit diagram 181-, 251-models ....................................................................................................................................... 15
3.2.1. PFC Choke L 2 .................................................................................................................................................................... 15
3.2.2. PFC circuit auxiliary transformer T 3 ................................................................................................................................. 15
3.2.3. Main circuit card Z 1 ......................................................................................................................................................... 15
3.2.3.1. EMC Filter .................................................................................................................................................................... 15
3.2.3.2. Inrush current limiting ................................................................................................................................................. 15
3.2.3.3. IGBT driver ................................................................................................................................................................... 15
3.2.3.4. Current transformer T1 ............................................................................................................................................... 15
3.2.3.5. Main circuit .................................................................................................................................................................. 15
3.2.3.6. PFC Boost control circuitry .......................................................................................................................................... 16
3.3. Main circuit diagram 253-, 323-models ....................................................................................................................................... 16
3.3.1. Main circuit card Z 1 ......................................................................................................................................................... 16
3.3.1.1. EMC filter ..................................................................................................................................................................... 16
3.3.1.2. Inrush current limiting ................................................................................................................................................. 16
3.3.1.3. IGBT driver ................................................................................................................................................................... 16
3.3.1.4. Current transformer T1 ............................................................................................................................................... 16
3.3.1.5. Main circuit .................................................................................................................................................................. 16
3.4. Main circuit diagram 253MV-, 323MV-models ............................................................................................................................ 18
3.4.1. General ................................................................................................................................................................................ 18
3.4.2. Main circuit card Z 1 ......................................................................................................................................................... 18
3.4.2.1. EMC filter ..................................................................................................................................................................... 18
3.4.2.2. Inrush current limiting ................................................................................................................................................. 18
3.4.2.3. IGBT driver ................................................................................................................................................................... 18
3.4.2.4. Current transformer T1 ............................................................................................................................................... 18
3.4.2.5. Main circuit .................................................................................................................................................................. 18
3.4.2.6. PFC Boost control circuitry .......................................................................................................................................... 18
4. MAIN CIRCUIT CARD Z 1 .................................................................................................................................................................... 19

SERVICE MANUAL
KEMPACT RA_V_1.2
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4.1. Kempact 181, 251 ........................................................................................................................................................................ 19
4.1.1. Connectors ........................................................................................................................................................................... 19
4.2. Kempact 253, 323 ........................................................................................................................................................................ 21
4.2.1. Connectors ........................................................................................................................................................................... 21
4.3. Kempact 253MV, 323MV ............................................................................................................................................................. 23
4.3.1. Connectors ........................................................................................................................................................................... 23
5. SECONDARY RECTIFIER CARD Z 2 ...................................................................................................................................................... 25
5.1. Connectors ................................................................................................................................................................................... 25
6. CONTROL CARD A 1 ........................................................................................................................................................................... 26
6.1. Leds .............................................................................................................................................................................................. 26
6.2. Connectors ................................................................................................................................................................................... 26
7. PANEL CARD P 1 ................................................................................................................................................................................ 28
7.1. Connectors ................................................................................................................................................................................... 28
8. OPERATIONAL MEASURINGS AND TESTS ............................................................................................................................................. 29
8.1. Kempact 181, 251 ........................................................................................................................................................................ 29
8.1.1 Primary rectifier V24, 25 ....................................................................................................................................................... 29
8.1.2. IGBT module V1 ................................................................................................................................................................... 3
8.2. Kempact 253, 323 ........................................................................................................................................................................ 31
8.2.1. Primary rectifier, V1 ............................................................................................................................................................. 31
8.2.2. IGBT module, V2 ................................................................................................................................................................. 32
8.3. Kempact 253MV, 323MV ............................................................................................................................................................. 33
............................................................................................................................................................................................................ 33
8.3.1. Primary rectifier, V31 ........................................................................................................................................................... 33
8.3.2. IGBT module, V1 ................................................................................................................................................................. 34
8.5. PTC’s, overheat protection ........................................................................................................................................................... 36
8.6. Control card A 1 ........................................................................................................................................................................ 36
9. MAIN COMPONENTS INSTALLATION .................................................................................................................................................... 36
9.1. Main circuit card Z 1 .................................................................................................................................................................. 36
9.2. Secondary rectifier card Z 2 ...................................................................................................................................................... 37
9.3. Other components ....................................................................................................................................................................... 37
1 . ERROR CODES ..................................................................................................................................................................................... 38
General
Kempact RA(Regular / Adaptive ) welding machines are compact MIG/MAG welding machines designed for professional use.
The power source part of the machine is based on inverter technology. IGBTs are used as power switches in the inverter. Kem-
pact RA welding machines also contain all circuitry that is needed to drive wire feeder part of the machine and also easy to use
intuitive user interface. Most of the welding machine functions are controlled using a microcontroller.
Before removing any covers or commencing any testing or measurement disconnect the power source from the mains voltage.
Dangerous DC voltage may still exist after the removal of the input voltage. Machine discharges the voltage while it is turned
off, but it is always better to ensure this by measuring the voltage.
Digital multimeters may give different values depending the specifications they have. For example diode measuring values may
vary between the multimeters models. Special attention must be considered while working with the internal parts.
The device may be repaired only by a person legally authorized to perform electrical work.

SERVICE MANUAL
KEMPACT RA_V_1.2
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1. PARTS OF MACHINE
Kempact RA (253, 323)

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KEMPACT RA_V_1.2
4 (4 )
Kemppi Oy
Kempact RA (253, 323)
NOTE !
Spare part info available from: [e-mail] (email).

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KEMPACT RA_V_1.2
5 (4 )
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2. TECHNICAL INFORMATION
2.1. Technical data
Kempact 181A Kempact 251R, 251A
Connection voltage 5 /6 Hz 23 V+- 15% 1~ 5 /6 Hz 24 V+- 15% 1~
Rated power at max. current 5 % ED I1max (18 A) 5.16VkA/5.1kW 3 % ED I1max (25 A) 8.5kVA/8.4kW
Supply current 5 % ED I1max (18 A) 22A 3 % ED I1max (25 A) 36A
1 % EDI1eff (14
A)
16
A
1 % EDI1eff (15 A)
17
A
Connection cable H 7RN-F
3G1.5 (1.5mm2,
5m) H 7RN-F
3G2.5 (2.5mm2,
5m)
Fuse Type C 16A Type C 2 A
Welding range
1 V/2 A -
26V/18 A
1 V/2 A -
29V/25 A
No load voltage
36V
36V
Idle power 35W 35W
Power factor at max. 18 A/25,75V .99 25 A/26.5V .99
Efficiency at 1 % ED 14 A/21V .82 15 A/21.5V .82
Wire feed speed adjustment
range 1. -14. m/min 1. -18. m/min
Voltage adjustment range 8. -26. V 8. -29. V
Filler wires
Fe solid
.8…1.2 mm
.8…1.2 mm
Fe cored wires .8…1.2 mm .8…1.2 mm
Ss .8…1.2 mm .8…1.2 mm
Al 1. …1.2 mm 1. …1.2 mm
CuSi .8…1. mm .8…1. mm
wire spool max 3 mm/ 2 kg 3 mm/ 2 kg
Shielding gases
CO2, Ar, Ar+CO2
mixed
CO2, Ar, Ar+CO2
mixed
External dimensions LxWxH 623x579x1 7 mm LxWxH 623x579x1 7 mm
Weight
Not including gun and
gables 44 kg
Not including gun and
gables 44 kg
Temperature class F(155 C) F(155 C)
EMC class A A
Degree of protection IP23S IP23S
Operating temperature range -2 …+4 °C -2 …+4 °C
Storage temperature range -4 …+6 °C -4 …+6 °C
Standards
IEC 6 974
-
1
IEC 6 974
-
1
IEC 6 974-5 IEC 6 974-5
IEC 6 974-1 IEC 6 974-1
IEC 61 -3-12 IEC 61 -3-12

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KEMPACT RA_V_1.2
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Kempact 253R, 253A
Kempact 323R, 323A
Connection voltage 5 /6 Hz 4 V+- 15% 3~ 5 /6 Hz 4 V +- 15% 3~
Rated power at max. current 4 % ED I1max (25 A) 8.34kVA/7.73kW 35% ED I1max (32 A) 12kVA/11.3kW
Supply current 4 % ED I1max (25 A) 11.9A 35% ED I1max (32 A) 17.2A
1 % EDI1eff (15 A) 6.1A 1 % EDI1eff (19 A) 8.2A
Connection cable H 7RN-F
4G1.5 (1.5mm2,
5m) H 7RN-F
4G1.5 (1.5mm2,
5m)
Fuse
Type C
1 A
Type C
1 A
Welding range
1 V/2 A -
31V/25 A
1 V/2 A -
32.5V/32 A
No load voltage 41V 45V
Idle power 25W 25W
Power factor at max. 25 A/26.5V .93 32 A/3 V .94
Efficiency at 1 % ED 15 A/21.5V .88 19 A/23.5V .86
Wire feed speed adjustment
range 1. -18. m/min 1. -2 . m/min
Voltage adjustment range 8. -31. V 8. -32.5V
Filler wires Fe solid .8…1.2 mm .8…1.2 mm
Fe cored wires .8…1.2 mm .8…1.2 mm
Ss .8…1.2 mm .8…1.2 mm
Al 1. …1.2 mm 1. …1.2 mm
CuSi .8…1. mm .8…1. mm
wire spool max 3 mm/ 2 kg 3 mm/ 2 kg
Shielding gases
CO2, Ar, Ar+CO2
mixed
CO2, Ar, Ar+CO2
mixed
External dimensions LxWxH 623x579x1 7 mm LxWxH 623x579x1 7 mm
Weight
Not including gun and
gables 44 kg
Not including gun and
gables 44 kg
Temperature class F(155 C) F(155 C)
EMC class
A
A
Degree of protection IP23S IP23S
Operating temperature range -2 …+4 °C -2 …+4 °C
Storage temperature range -4 …+6 °C -4 …+6 °C
Standards IEC 6 974-1 IEC 6 974-1
IEC 6 974-5 IEC 6 974-5
IEC 6 974-1 IEC 6 974-1
IEC 61 -3-12 IEC 61 -3-12

SERVICE MANUAL
KEMPACT RA_V_1.2
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Kempact 253 MV
Kempact 323 MV
Connection voltage 5 /6 Hz
23 V -15% ... 4 V
+15% 5 /6 Hz
23 V -15% ... 4 V
+15%
Rated power at max. current
4 % ED I1max
(25 A)(23 V) 8.84kVA/8.38kW
35% ED I1max
(32 A)(23 V) 13.21kVA/12.47kW
4 % ED I1max
(25 A)(4 V) 8.54kVA/8. kW
35% ED I1max
(32 A)(4 V) 12.37kVA/11.73kW
Supply current
4 % ED I1max
(25 A)(23 V)
22.2A
35% ED I1max
(32 A)(23 V)
33.3A
4 % ED I1max
(25 A)(4 V) 12.3A
35% ED I1max
(32 A)(4 V) 17.8A
1 % EDI1eff
(15 A)(23 V) 1 .8A
1 % EDI1eff
(19 A)(23 V) 14.8A
1 % EDI1eff
(15 A)(4 V) 6.2A
1 % EDI1eff
(19 A)(4 V) 8.3A
Connection cable H 7RN-F
4G1.5 (1.5mm2,
5m) H 7RN-F 4G1.5 (1.5mm2, 5m)
Fuse Type C (23 V) 16A Type C (23 V) 16A
Type C (4 V) 1 A Type C (4 V) 1 A
Welding range
1 V/2 A
-
31V/25 A
1 V/2 A
-
32.5V/32 A
No load voltage 46V 5 V
Idle power 35W 35W
Power factor at max. 25 A/26.5V (23 V) .94 32 A/3 V (23 V) .94
25 A/26.5V (4 V) .93 32 A/3 V (4 V) .94
Efficiency at 1 % ED 15 A/21.5V (23 V) .79 19 A/23.5V (23 V) .8
15 A/21.5V (4 V) .82 19 A/23.5V (4 V) .83
Wire feed speed adjustment
range 1. -18. m/min 1. -2 . m/min
Voltage adjustment range 8. -31. V 8. -32.5V
Filler wires Fe solid .8…1.2 mm .8…1.2 mm
Fe cored wires .8…1.2 mm .8…1.2 mm
Ss .8…1.2 mm .8…1.2 mm
Al 1. …1.2 mm 1. …1.2 mm
CuSi .8…1. mm .8…1. mm
wire spool
max
3 mm/ 2 kg
3 mm/ 2 kg
Shielding gases
CO2, Ar, Ar+CO2
mixed
CO2, Ar, Ar+CO2
mixed
External dimensions LxWxH 623x579x1 7 mm LxWxH 623x579x1 7 mm
Weight
Not including gun and
gables 44 kg
Not including gun and
gables 44 kg
Temperature class
F(155 C)
F(155 C)
EMC class A A
Degree of protection IP23S IP23S
Operating temperature -2 …+4 °C -2 …+4 °C

SERVICE MANUAL
KEMPACT RA_V_1.2
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range
Storage temperature range -4 …+6 °C -4 …+6 °C
Standards IEC 6 974-1 IEC 6 974-1
IEC 6 974-5 IEC 6 974-5
IEC 6 974-1 IEC 6 974-1
IEC 61 -3-12 IEC 61 -3-12

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2.2. Main circuit diagrams

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* Please refer to Kemppi Channel for the latest version of main circuit drawings !

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3. DESCRIPTION OF OPERATIONS
Kempact RA welding machine consists of several circuit cards and separate components. In the following sections are
described the main components and separate cards functions.
Machine basic function (machine start up), after mains voltage is switched on:
1. DC-link capacitors are charged and if there is no over voltage condition inrush relay is switched on after a short delay
2. If there is PFC circuit it’s enabled after a short delay
3. Fans are started for a test run after a short delay
4. Welding is enabled
Kempact RA machines have following parts and components:
•Terminal block X 1
•Varistors R 1
•Main switch S 1
•Terminal block X 9
•Main circuit card Z 1
oEMC filter
oInrush current limiting
oIGBT driver
oCurrent transformer T1
oMain circuit
•PFC choke L 2 (181-, 251-, 253MV- and 323MV-models)
•PFC circuit auxiliary transformer T 3 (181-, 251-, 253MV- and 323MV-models))
•Test connector X 6
•Auxiliary transformer T 2
•Rectifier bridge G 3
•Control card A 1
•Cooling fans M 1 and M 2
•Gas valve Y 1
•Wire feed motor M 3
•Brights led card P 2
•Panel card P 1
•Main circuit card Z 1
•Secondary rectifier card Z 2
•Secondary choke L 1
•Output RFI filters C 1 and C 2
•Euro connector X 5

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3.1. Main components
3.1.1. Terminal block X001
•Mains cable is connected to the terminal block X 1. The terminal block is located in the mains cable connection box
on the back plate of the machine. Also varistors R 1 are connected to this terminal block. From the terminal block
mains voltage is wired to main switch S 1
3.1.2. aristors R001
•The varistors are located in the mains cable connection box on the backside of the welding machine
•The purpose of the varistors is to protect the welding machine against voltage spikes coming from the mains
3.1.3. Main switch S001
•The main switch is located in the upper part of the machine close to the user interface
3.1.4. Terminal block X009
•From the main switch S 1 mains voltage is wired to terminal block X 9 which is located on the front side of the
component frame. From this terminal block mains voltage is wired to the main circuit card Z 1
•PE (protective earth) is wired from this terminal block into the component frame and connected to a chassis ground
terminal
3.1.6. Test connector X006
•Possible to measure DC-link voltage during service
3.1.7. Auxliary transformer T002 and rectifier bridge G003
•Auxliary transformer is a 6 VA toroidal transformer
•It has 23 V and 4 V inputs and 18V output
•23 V input is used in 181 and 251 machines
•4 V input is used in 253 and 323 machines
•Auxliary transformer output voltage is rectified using rectifier bridge G 3. Both the auxiliary transformer and the
rectifier bridge are located inside the component frame
3.1.8. Control card A001
•All machines have different type of control card according machine size and type.
•MVU card has +24V aux power which regulates +24V when input voltage changes (+24V aux power components are
not installed on MVU control card).
3.1.8.1. Auxiliary power supply
•Auxliary voltage +24V is used by fans, gas valve, inrush relay and brights LED. This voltage is also used to drive opto-
coupler that enables PFC and panel backlight. To generate +24V voltage auxliary transformer T 2 output is full wave
rectified using rectifier bridge G 3
•Auxliary voltage +15V is used by IGBT driver (V2 , V22, V23, V25 etc.), PWM IC (N5), motor control half bridge driver
(N2) and other circuits
•Auxliary voltage +5V is used by microcontroller N7, panel card P 1 and other circuits
3.1.8.2. Microcontroller
•Many of the control card A 1 functions are using the microcontroller N7. Basic functions of the microcontroller
include controlling output voltage of the inverter. The microcontroller measures output voltage and changes peak
current reference of the inverter to regulate it
•The microcontroller also regulates wire feed speed by setting motor current reference and measuring EMF of the
motor
3.1.8.3. Motor control
•Wire feed motor control is based on EMF (electro magnetic force) measurement principle

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•Wire feed mechanism doesn’t have tachometer, instead motor current is driven to zero every ca. 1 ms and the EMF
of the motor is measured before motor current is increased again. This EMF information is then used to regulate
motor speed
•The microcontroller measures motor EMF and controls motor current to regulate motor speed
3.1.8.4. PWM
•PWM (pulse width modulation) circuit is for controlling the inverter
•Peak current-mode control is used to directly control primary current which is measured by current transformer T1 l
3.1.9. Fans M001, M002
•Machine fans are controlled by the control card A 1 microcontroller. If there are two fans (3~models) in the ma-
chine they are started in sequence so that second fan is started after 3s delay. When welding starts fans are started
and when welding stops fans are stopped after post run time
•In error situation fans are always on
•Fans are stopped if arc is not established during first 5s after start
3.1.10. Solenoid valve Y001
•Solenoid valve is controlled by control card A 1 auxiliary voltage + 24 V
3.1.11. Wire feed motor M003
•Wire feed motor control is based on EMF (electro magnetic force) measurement principle. Wire feed mechanism
doesn’t have tachometer, instead motor current is driven to zero every ca. 1 ms and the EMF of the motor is meas-
ured before motor current is increased again. This EMF information is then used to regulate motor speed. Wire feed
motor speed control is done using the microcontroller. The microcontroller measures motor EMF and controls motor
current to regulate motor speed
•There is no special wire inch button. Wire inch is started like normal welding using the gun. When the user pushes
start button wire feed motor and the power source start. Wire feed speed is creep start speed which is slower than
normal wire feed speed. If arc is not established during first 5s the power source is shut down but wire feeding con-
tinues with creep start speed for 3 s. When the inverter is ON operating voltage for the wire feed motor is taken
from the output of the power source. When the inverter is SHUT DOWN after 5s operating voltage for the wire feed
motor is taken from the auxliary transformer for safety reasons. Because of this current limit of the wire feed motor
has to be lowered. For this reason also torque of the wire feed motor is reduced after 5s
3.1.12. Brights led card P002
•Controlled by control card A 1 auxiliary voltage + 24 V
3.1.13. Panel card P001
•There is two panel versions R and A (R-version has limited functions). Panel is connected to the control card A 1
with 16-wire ribbon cable
oWhen machine start up panel is showing power source size and SW version
3.1.14. Main transformer T001
•In the 181 and 251 machines the main transformer has 19 turn primary winding and center tapped secondary 2 + 2
turns (turns ratio 9.5:1)
•In the 253 machine the main transformer has 27 turn primary winding and center tapped secondary 2 + 2 turns
(turns ratio 13.5:1)
•In the 323 machine the main transformer has 25 turn primary winding and center tapped secondary 2 + 2 turns
(turns ratio 12.5:1)
3.1.15. Secondary rectifier card Z002
•Z 2 is used to rectify the secondary current. There are 4 6 A diodes connected in parallel in both legs of the rectifier
(V1 – V8) in 323 power source. 25 amps machine has 3+3 diodes
•Capacitors C1 and C2 and resistors R3 and R4 form a snubber circuit. The snubber circuit reduces the voltage stress of
the diodes caused by the reverse recovery current snap off
•Varistors R1 and R2 are for TIG ignition spark protection

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•Operating voltage for the wire feed motor is rectified to capacitors C3-C5
3.1.16. Secondary choke L001
•The secondary choke L 1 reduces ripple content of the secondary current
3.1.17. Output RFI filter C001, C002
•Capacitors C 1 and C 2 connected to the dowel screws (+ and -) reduce radio frequency interference
3.1.18. Output terminal X004
•Dix connector X 4
3.1.19. Euro connector X005
3.2. Main circuit diagram 181-, 251-models
•181 and 251 machines have many common technical details with 253 and 323 machines. They have e.g. the same
A 1, P 1, P 2 and Z 2 cards. Main differences to 253 and 323 machines are described here
3.2.1. PFC Choke L002
181 and 251 machines include PFC (Power Factor Correction) circuit. This is implemented using boost topology. The Boost to-
pology has choke in the input side of the converter. In Kempact 181 and 251 this choke is located on the front side of the com-
ponent frame from where it is wired into the component frame
3.2.2. PFC circuit auxiliary transformer T003
PFC circuit auxiliary power is generated using small toroidal transformer located inside the component frame
3.2.3. Main circuit card Z001
3.2.3.1. EMC Filter
•Capacitors C7, C1 , C15, C16 and inductor T6 form an EMC filter. The purpose C17 and R18 is to dampen common
mode transients coming from mains
3.2.3.2. Inrush current limiting
•PTC resistors R16 and R17 limit inrush current when the power source is switched on. PTCs are bypassed with relays
K1 and K2 after DC link capacitors have been charged. Relays K1 and K2 are controlled by the microcontroller
3.2.3.3. IGBT driver
•IGBT driver consists of gate transformers T2 and T3 and surrounding components
3.2.3.4. Current transformer T1
•Current transformer T1 is monitoring primary current and stops power stage operation if current is raising too high
3.2.3.5. Main circuit
•The main circuit consists of boost type PFC circuit followed by H-bridge type converter.
•Both parts of the main circuit are implemented using the same 6 V, 75A six pack IGBT module
•One leg of the IGBT module is used for the Boost PFC circuit. Lower IGBT is used as the Boost power switch and the
anti-parallel diode of the upper IGBT as the boost diode
•The switching frequency of the boost circuit is ca. 15 kHz. The boost circuit raises DC link voltage to ca. 37 V. Boost
input current is measured using shunt resistors R58, R59, R65, R66. H – bridge is implemented using the other two
legs of the IGBT module

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3.2.3.6. PFC Boost control circuitry
•PFC control circuitry is located on the primary side. Auxliary transformer T 3 supplies operating voltage for the PFC
control circuitry. The output voltage of the T 3 is first rectified and then linear regulator is used to regulate auxiliary
voltage to 15V. PFC control IC N1 regulates DC-link voltage to approximately 37 V
3.3. Main circuit diagram 253-, 323-models
3.3.1. Main circuit card Z001
3.3.1.1. EMC filter
•Capacitors C5 - C7, C8 - C1 , C19 - C21 and inductors T4 and L1 form an EMC filter
•First part of the filter is three phase filter which is located before the three phase rectifier V2
•Second part is DC filter (L1) which is located after three phase rectifier
3.3.1.2. Inrush current limiting
•PTC resistor R1 limits inrush current when the power source is switched on
•R1 is bypassed with relays K1 and K2 after DC link capacitors C17, C18 have been charged
•Relays K1 and K2 are controlled with the microcontroller
3.3.1.3. IGBT driver
•IGBT driver consists of gate transformers T2 and T3 and surrounding components
3.3.1.4. Current transformer T1
•Current transformer T1 is monitoring primary current and stops power stage operation if current is raising too high
3.3.1.5. Main circuit
•Main circuit topology is H-bridge. The H-bridge topology requires four power switches which are implemented using
IGBT module V2. The switching frequency of the H – bridge is 2 kHz
•253 power source uses 5 A module
•323 power source uses 75A module
G1
G3
G2
G4
U
G1
U
G2
U
G3
U
G4
U
T1
U
G5
U
L1
G5
L1
U
G1
U
G3
U
G4
U
G2
U
T1
U
G5
U
L1
Approx
.. + 57
0 V
When IGBT-transistors G1 and G4 conduct, there is a positive voltage U
T1 in main transformer T1 primary and when IGBT-
transistors G2 and G3 conduct there is a negative voltage U
T1 in main transformer primary. Power is adjusted by changing the
IGBT timings (PWM).

SERVICE MANUAL
KEMPACT RA_V_1.2
17 (4 )
Kemppi Oy

SERVICE MANUAL
KEMPACT RA_V_1.2
18 (4 )
Kemppi Oy
3.4. Main circuit diagram 253MV-, 323MV-models
3.4.1. General
•323 MV and 253 MV machines have many common technical details with the 323 and 253 machines. They have e.g.
the same Z 2, A 1 and P 1 cards. Also main transformers are same. Main difference is of course that they are
multi voltage machines. This means that these machines can be connected to any mains voltage between 23 V -15%-
4 V +15%. The selection of input voltage is automatic. In fact, the multi voltage machines use basically the same
technology as the one phase machines. This means that there is first a boost type converter which raises rectified in-
put voltage to approximately 63 V DC-link voltage. This DC-link voltage is then used as input voltage for the H-bridge.
So PFC boost is used as an input stage for the H-bridge. Regardless of input voltage (23 V -15% - 4 V +15%) boost
stage raises DC-link voltage to same value so the input voltage to the H-bridge stays the same.
3.4.2. Main circuit card Z001
3.4.2.1. EMC filter
•Capacitors C5 – C1 and inductor T6 forms an EMC filter
3.4.2.2. Inrush current limiting
•PTC resistor R7 limits inrush current when the power source is switched on
•PTC is bypassed with relays K1 and K2 after DC link capacitors have been charged
•Relays K1 and K2 are controlled with the microcontroller
3.4.2.3. IGBT driver
•IGBT driver consists of gate transformers T2 and T3 and surrounding components
3.4.2.4. Current transformer T1
•Current transformer T1 is monitoring primary current and stops power stage operation if current is raising too high
3.4.2.5. Main circuit
•The main circuit consists of boost type PFC circuit followed by H-bridge type converter.
•Both parts of the main circuit are implemented using the same 12 V, 1 A six pack IGBT module
•One leg of the IGBT module is used for the Boost PFC circuit. Lower IGBT is used as the Boost power switch and the
anti-parallel diode of the upper IGBT as the boost diode. H – bridge is implemented using the other two legs of the
IGBT module
•The switching frequency of the boost circuit is ca. 13 kHz. The boost circuit raises DC link voltage to ca. 63 V. Boost
input current is measured using shunt resistors R58, R59, R65, R66.
•The operation of the H-bridge is the same as with the 323 and 253 machines.
3.4.2.6. PFC Boost control circuitry
•PFC control circuitry is located on the primary side. Auxliary transformer T 3 supplies operating voltage for the PFC
control circuitry. The output voltage of the T 3 is first rectified and then linear regulator is used to regulate auxiliary
voltage to 15V. PFC control IC N1 regulates DC-link voltage to approximately 63 V.

SERVICE MANUAL
KEMPACT RA_V_1.2
19 (4 )
Kemppi Oy
4. MAIN CIRCUIT CARD Z 1
4.1. Kempact 181, 251
4.1.1. Connectors
Pin Signal Description
X1 Mains voltage Main voltage connector
X2
Mains voltage
Mains voltage connector
Pin Signal
X4 Chassis ground connector
Pin
Signal
X5 Auxiliary transformer connection, auxliary transformer is protected with PTC resistors R63 and R64
X6 PFC Auxiliary transformer connection, auxliary transformer is protected with PTC resistors R63 and R64