Measurement Of Voltages And Currents - Mitsubishi Electric FR-F740 EC Instruction Manual

Measurements on the main circuit
8.2.3

Measurement of voltages and currents

Since voltages and currents in the primary and secondary side of the inverter include harmonics,
different meters indicate different measured values.
When the inverter-to-motor wiring length is large, especially in the 400V class, large-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.
When measuring and indicating the output voltage and output current of the inverter, it is rec-
ommended to utilize the AM and CA terminal output function of the inverter.
When using measuring instruments for the normal frequency range, carry out the measure-
ments as described below.
Power supply
Instrument types
Fig. 8-16: Examples of measuring points and instruments
8 - 18
Input
voltage
Input
current
Inverter
Maintenance and inspection
Output
voltage
Output
current
To the motor
Moving-iron type
Electrodynamometer type
Moving-coil type
Rectifier type
I001313E