Secondary Rectifier Functions And Main Components - Kemppi MLS 2300 ACDC Service Manual

Secondary rectifier Z002
Functions and main components
Secondary diode card Z002 includes the following operational blocks:
- Full wave rectifying for secondary
- AC –welding auxiliary pulse rectifying
- Damping circuits
- Machine size code
- Voltages of the main transformer's secondary are rectified by a full wave rectifier, which consists
of parallel connected diodes (60A/600V). Note ! Diodes V11 – V15 and V16 – V20 are insulated
from the heat sink !!!
- Damping circuits (RC) reduce the voltage stress of secondary diodes. The machine size is coded
by resistor R1 s value.
- AC –welding auxiliary pulses are developed from the voltages of the auxiliary coils of the main
transformer T001. AC –welding auxiliary pulses stabilize the AC -arc by increasing secondary
voltage up to +/- 350 V (max. about 500 s) at the beginning of the half cycle. Chokes L1 and L2
limit the current to a few amps.
AC -welding
auxiliary pulse chokes
AC -welding
auxiliary pulse
diodes
Negative side diodes
insulated from heat sink !!!
Positive side
diodes
18