Hitachi SJ7002 Series Instruction Manual page 275

IGBT Test Method
The following procedure will check the power module, including inverter transistors (IGBTs),
IPM, diodes, and thyrister until replacement of inverter (1,000,000 start/stop cycles):
1. Disconnect input power to terminals [R, S, and T] and motor terminals [U, V, and W].
2. Disconnect any wires from terminals [P] and [RB] for regenerative braking.
3. Use a Digital Volt Meter (DVM) and set it for 1 ohm resistance range. You can check the
Almost infinite ohms = "non-conducting," and 0 to 10 ohms = "conducting."
NOTE: The resistance values for the diodes or the transistors will not be exactly the same, but
they will be close. If you find a significance difference, a problem may exist.
NOTE: Before measuring the voltage between [P] and [N] with the DC current range, confirm
that the smoothing capacitor is discharged fully, then execute the tests.
PD P RB
Converter
D1 D2 D3
R
+
S
C
T
D4 D5 D6
N
status of the charging state of terminals [R, S, T, U, V, W, RB, P, and N] of the inverter and
the probe of the DVM by measuring the charging state.
Inverter
TR1 TR2 TR3
U
V
W
TR7 TR4 TR5 TR6
DVM Probe
Circuit Type
+
D1 R
PD
D2 S
PD
D3 T
PD
Converter
D4 R
N
D5 S
N
D6 T
N
TR1 U
P
TR2 V
P
TR3 W
P
Inverter
TR4 U
N
TR5 V
N
TR6 W
N
6–27
SJ700 Inverter
2
Measured Value
–
PD Non-conducting
R Conducting
PD Non-conducting
S Conducting
PD Non-conducting
T Conducting
N Conducting
R Non-conducting
N Conducting
S Non-conducting
N Conducting
T Non-conducting
P Non-conducting
U Conducting
P Non-conducting
V Conducting
P Non-conducting
W Conducting
N Conducting
U Non-conducting
N Conduct
V Non-conducting
N Conducting
W Non-conducting