Kemppi WeldForce KPS 3500 Service Manual page 7

Main circuit components
Smoothing capacitors
4 x 25 µ F/ 700 VDC
Work capacitors
30 x 0,15 µ F/ 1000 VDC
Discharging resistors
4 x 33 k Ω / 2 W
(KEMPPI WELDFORCE
Inverter´s main parts are the workcapacitors, IGBT-transistors and the main transformer T001.
Inverter´s power adjustment is based on pulse width modulation (PWM). RC-protections ease the
stress on the semiconductors.
Commutation unit
The chokes LL301 and LL302 of the commutation unit reduce the losses of the IGBTs during
the switching. The current transformer LT301 monitors the primary side current. According
to it´s measurement the frequency of the power source is adjusted (14... 24 kHz).
TM
5500)
IGBT-modules
2 x 200 A/ 1200 V
RC-protection
7