Checking The Inverter And Converter Modules - Mitsubishi Electric A800 Instruction Manual

Inspection item
5.1.4

Checking the inverter and converter modules

Preparation
• Disconnect the external power supply cables (R/L1, S/L2, T/L3) and motor cables (U, V, W). (The cables between the
inverter and the converter unit, between the inverters, and between the converter units does not need to be removed.)
• Prepare a tester. (For the resistance measurement, use the 100  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  to
several tens of . If all measured values are almost the same, although these values are not constant depending on the
module type and tester type, the modules are without fault.
Module device numbers and terminals to be checked
Converter module
D1 D2 D3
R/L1
C
S/L2
T/L3
D4 D5 D6
Tester
polarity
R/L1, P/+
D1
P/+ R/L1,
S/L2, P/+
D2
P/+ S/L2,
T/L3 P/+
D3
P/+ T/L3
U P/+
TR1
P/+ U
V P/+
TR3
P/+ V
W P/+
TR5
P/+ W
(Assumes the use of an analog meter.)
90
PRECAUTIONS FOR MAINTENANCE AND INSPECTION
Inverter module
P/+ P/+
TR1
C
TR4
N/- N/-
Tester
polarity
Result
Discontinuity R/L1,
D4
Continuity N/- R/L1, Discontinuity
Discontinuity S/L2,
D5
Continuity N/- S/L2, Discontinuity
Discontinuity T/L3
D6
Continuity N/- T/L3 Discontinuity
Discontinuity U
TR4
Continuity N/-
Discontinuity V
TR6
Continuity N/-
Discontinuity W
TR2
Continuity N/-
TR3 TR5
U
V
W
TR6 TR2
Result
N/- Continuity
N/- Continuity
N/- Continuity
N/- Continuity
U Discontinuity
N/- Continuity
V Discontinuity
N/- Continuity
W Discontinuity