Checking The Inverter And Converter Semiconductor Devices - Mitsubishi Electric A800 Plus Instruction Manual

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 inverter and the converter
unit (FR-CC2) can be measured with those cables connected.)
• Prepare a continuity tester. (For the resistance measurement, use the 100 Ω range.)
Checking method
Change the polarity of the tester alternately at a semiconductor device (transistor) on an electrical path between two terminals
among the inverter main circuit terminals R/L1, S/L2, T/L3, U, V, W, P/+, and N/- to 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.
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.)
100
PRECAUTIONS FOR MAINTENANCE AND INSPECTION
Inverter unit
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