Mitsubishi Electric FR-A802-P Instruction Manual page 97

Inspection item
5.1.4
Checking the inverter and converter
semiconductor devices
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 continuity 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 . 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.
Semiconductor device numbers and terminals to be checked
Converter unit
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
(Assuming that an analog meter is used.)
96
PRECAUTIONS FOR MAINTENANCE AND INSPECTION
Inverter
P/+ P/+
TR1
C
TR4
N/- N/-
Tester
polarity
Continuity
No R/L1
D4
Yes N/- R/L1
No S/L2
D5
Yes N/- S/L2
No T/L3
D6
Yes N/- T/L3
No U
TR4
Yes N/-
No V
TR6
Yes N/-
No W
TR2
Yes N/-
TR3 TR5
U
V
W
TR6 TR2
Continuity
N/- Yes
No
N/- Yes
No
N/- Yes
No
N/- Yes
U No
N/- Yes
V No
N/- Yes
W No