Lincoln Electric 11141 Service Manual page 64

F-18
J21
1 4
5 8
J21
PRIMARY CURRENT TRANSDUCER(S)
TEST
Current Transducers (CT) Test Description
The two primary current transducers (CT2 and
CT3) monitor the primary currents in the primary
windings of the main transformer. See the Wiring
Diagram. The output of the CTs is sent to the con-
trol board for processing. If the primary current
feedback signals (output of the CTs) are not bal-
anced the control board will adjust the pulse width
modulation (PWM) signal sent to the switch board
to keep the IGBTs balanced. Also, if either side of
the switch board is supplying too much current to
the main transformer the control board will remove
the PWM signal and the inverter will be shut off to
protect the switch board.
TROUBLESHOOTING AND REPAIR
MAIN SWITCH BOARD TEST (continued)
FIGURE F.3 – PLUG J21 LEADS AND LOCATIONS
207
-
201
208
203
POWER WAVE
+ -
204
205
- + -
The best way to test a current transducer is by
measuring the inductance. The CTs are housed on
the IGBT switch board. The measurements should
always be made without removing the IGBT switch
board from the machine.
MATERIALS NEEDED
Volt-Ohmmeter with inductance measuring
capabilities (Amprobe Model 37XR-A)
Wiring Diagram
® 355M/405M
F-18
202
J22
+
209
+
206
J20