Mitsubishi Electric 800 Series Instruction Manual page 600

7.1.4 Checking the inverter module and the converter module
 Preparation
• Disconnect the external power supply cables (R/L1, S/L2, T/L3) and motor cables (U, V, W).
• Prepare a continuity tester. (For the resistance measurement, use the 100 Ω range.)
 Checking method
Change the polarity of the tester alternately at the inverter terminals R/L1, S/L2, T/L3, U, V, W, P/+, and N/- and check the
electric continuity.
NOTE
• Before measurement, check that the smoothing capacitor is discharged.
• At the time of electric discontinuity, the measured value is almost . When there is an instantaneous electric continuity,
due to the smoothing capacitor, the tester may not indicate . At the time of electric continuity, the measured value is
several Ω to several tens of Ω. When all measured values are almost the same (although values may not be constant
depending on the tester type), it shows that there are no electrical paths with problems.
 Module device numbers and terminals to be checked
Tester
polarity
Converter D1 R/L1 P/+
module
P/+ R/L1
D2 S/L2 P/+
P/+ S/L2
D3 T/L3 P/+
P/+ T/L3
Inverter TR1 U P/+
module
P/+ U
TR3 V P/+
P/+ V
TR5 W P/+
P/+ W
(Assuming that an analog meter is used.)
P/+
Converter module
D1 D2 D3
R/L1
C
S/L2
T/L3
D4 D5 D6
N/−
Result Tester
polarity
Discontinuity D4 R/L1
Continuity N/-
Discontinuity D5 S/L2
Continuity N/-
Discontinuity D6 T/L3
Continuity N/-
Discontinuity TR4 U
Continuity N/-
Discontinuity TR6 V
Continuity N/-
Discontinuity TR2 W
Continuity N/-
Inverter module
TR1 TR3 TR5
U
V
W
TR4 TR6 TR2
Result
N/- Continuity
R/L1 Discontinuity
N/- Continuity
S/L2 Discontinuity
N/- Continuity
T/L3 Discontinuity
N/- Continuity
U Discontinuity
N/- Continuity
V Discontinuity
N/- Continuity
W Discontinuity
7. PRECAUTIONS FOR MAINTENANCE AND INSPECTION
3
4
5
5
5
5
7
8
9
10
599
7.1 Inspection item