12
Electric Power Generation
2020.07 / f
Installation and maintenance
R180
AVR
5599 en -
7 - MULTIMETER TEST
WARNING
The freewheel diode can be tested by a
digital multimeter in diode tester mode.
Connect the red lead to F2 and the black
lead on the multimeter to F1. The multimeter
will display 0.4V to 0.6V in diode test mode
if the freewheel diode is OK. 0V or OL on the
multimeter indicates a faulty freewheel
diode.
IGBT Tab is connected to +DC bus and A1 is
connected to -DC bus on the AVR.
These two connections can be used to test
the IGBT and input bridge connected at X1,
X2, Z1 and Z2.
Connect the multimeter black lead to IGBT
Tab.
Connect the red lead to X1: the multimeter
will display 0.4V to 0.6V.
Connect the red lead to X2: the multimeter
will display 0.4V to 0.6V.
Connect the red lead to Z1: the multimeter
will display 0.4V to 0.6V.
Connect the red lead to Z2: the multimeter
will display 0.4V to 0.6V.
Connect the red lead to A1 and connect the
black lead to X1: the multimeter will display
0.4V to 0.6V.
Connect the black lead to X2: the multimeter
will display 0.4V to 0.6V.
Connect the black lead to Z1: the multimeter
will display 0.4V to 0.6V.
Connect the black lead to Z2: the multimeter
will display 0.4V to 0.6V.
If the multimeter displays 0V or OL in diode
test, the bridge rectifier diodes are faulty.
If the fuses are open, X1 and Z2 will display
OL in diode test mode.
If IGBT Tab and F1 display 0 ohm, the IGBT
is faulty.
Sensing input resistance test
Resistance between V and A1:
1.3 MΩ approx.
Resistance between L1 and A1:
1 MΩ approx.
Resistance between L2 and A1:
1 MΩ approx.
Resistance between W and A1:
1.3 MΩ approx.
