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5.2
Measurement of main circuit voltages,
currents and powers
Since the voltages and currents on the inverter power supply and output sides include harmonics, measurement data
depends on the instruments used and circuits measured.
When instruments for commercial frequency are used for measurement, measure the following circuits with the instruments
given on the next page.
NOTE
• When installing meters etc. on the inverter output side
When the wiring length between the inverter and the motor is large, the meters and CTs may generate heat due to line-to-line
leakage current. Therefore, choose the equipment which has enough allowance for the current rating.
To measure and display the output voltage and output current of the inverter, it is recommended to use terminal AM and FM
output functions of the inverter.
Three-phase
power supply
Measurement of main circuit voltages, currents and powers
Input voltage
Input current
Inverter/
converter unit
Ar
R/L1
U
W11
Vr
V
As
W12
S/L2
Vs
At
T/L3
W
W13
Vt
P/+
N/-
V
+
-
PRECAUTIONS FOR MAINTENANCE AND INSPECTION
Output voltage
Output current
Au
W21
Vu
To the motor
Av
Vv
Aw
W22
Vw
5
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