Mitsubishi Electric FR-A800, Instruction Manual

Page: 946 / 1042

Measurement of main circuit voltages, currents and powers Precautions for maintenance and inspection
7 - 12
7.2 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 cir-
cuits with the instruments given on the next page.
●
When installing meters etc. on the inverter output side
When the inverter-to-motor wiring length is large, especially in the 400 V class, small-capacity
models, 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 the terminal AM and FM/CA output functions of the inverter.
I001313E
Fig. 7-11: Examples of measuring points and instruments
Input
voltage
Input
current
Output
voltage
Output
current
Three phase
power supply
Inverter
Instrument types
To the motor
Moving-iron type
Electrodynamometer type
Moving-coil type
Rectifier type