Measurement Of Voltages And Currents - Mitsubishi Electric FR-E700 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 making measurement with the me-
ters designed for commercial frequency, use the following measuring instruments and circuits:
When installing meters etc. on the inverter output side
When the inverter-to-motor wiring length is large, especially in the 400V 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. When measuring and
indicating the output voltage and output current of the inverter, it is recommended to utilize the
AM-5 terminal output function of the inverter.
When using measuring instruments for the normal frequency range, carry out the measure-
ments as described below.
1-phase, 230V
3-phase, 400V
Power supply
Instrument types
* At, As, Vt, Vs, W12, W13 are only for the three-phase power input
specification models.
Fig. 8-10: Examples of measuring points and instruments
8 - 12
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
I002040E