Troubleshooting Problems With Diode Stack; Troubleshooting Problems With Igbt Module - Mitsubishi Electric R410A Service Handbook

[8-9 Troubleshooting Inverter Problems (TLMU) ]
8-9-15

Troubleshooting Problems with Diode Stack

(P168 model)
Measure resistances between each pair of terminals on the diode stack with a tester, and use the results for troubleshooting.
For cautionary notes on measuring diode stack resistance and information on the types of testers to be used, refer to the fol-
lowing page(s). [8-9-14 Troubleshooting Problems with Intelligent Power Module](page 273)
Judgment value (reference)
+ (P)
- (N)
to (L1)
Red (-)
to (L2)
to (L3)
8-9-16

Troubleshooting Problems with IGBT Module

(P72, P96, P120, P144 models)
Measure the resistances between each pair of terminals on the IGBT with a tester, and use the results for troubleshooting.
The terminals on the INV board are used for the measurement.
1) Notes on measurement
Check the polarity before measuring. (On the tester, black normally indicates plus.)
Check that the resistance is not open (
The values are for reference, and the margin of errors is allowed.
The result that is more than double or half of the result that is measured at the same measurement point is not allowed.
Disconnect all the wiring connected the INV board, and make the measurement.
2) Tester restriction
Use the tester whose internal electrical power source is 1.5V or greater
Use the dry-battery-powered tester.
(The accurate diode-specific resistance cannot be measured with the button-battery-powered card tester, as the applied volt-
age is low.)
Use a low-range tester if possible. A more accurate resistance can be measured.
HWE14080
Black ( + )
+ (P) - (N) to (L1)
- - 5 - 200
- -
5 - 200 -
5 - 200 -
5 - 200 -
) or not shorted (to 0 ).
- 274 -
External view
to (L2) to (L3)
5 - 200 5 - 200
- -
Internal circuit diagram
- -
- -
L1 L2 L3
+
L1
L2
L3
-
GB