Hitachi SJ100 SERIES Service Manual page 34

When there is no motor connected to the inverter, please use additional resistor like Fig. 7-2. There
will be a voltage at output terminal even the frequency command is naught due to the leakage current
of the semiconductor devices.
Frequency
Inverter
Additional resistor
5kohm 30W (200V class)
100W (400V class)
(2) Measurement of Input voltage and Input / output current
Use moving iron type ampere meter. (Refer to Fig. 7-3 and Table 7-1.)
(3) Measurement of Input and output power
Use electrodynamics type watt meter for single phase use. Make measurements for all 3 phases is
case there is an unbalance in voltages and currents.
L1
I
R
L2
I
S
L3 / N
I
T
U
V
W
2W
220kohm
Diode
600V 0.1A or above (200V class)
1000V 0.1A or above (400V class)
Fig. 7-2. Output voltage measurement circuit (without motor)
Frequency Inverter
L1
E W
R 11
L2
E W
S 12
L3 / N
E
T
Fig. 7-3. Measurement Instruments
Fundamental wave
+
effective value : V
V
DC
-
Moving coil type DC Volt meter
300V (200V class)
600V (400V class)
U/T1
I
U
V/T2
I
V
W/T3
I
W
7-2
= V * 1.1
AC DC
E W
U-V O1
Motor
E W
V-W O2
E
U-W