Mitsubishi Electric FREQROL-K Series Instruction Manual page 29

9.2 Measur~ng Methods for Voltage and Current
Since the primary and secondary voltages and currents of inverter contain higher harmonic waves,
measured values differ depending on measuring instruments and measured circuits.
When an instrument for commercral frequency is used for measurement, select one from the mea-
surlng instruments listed in Table 1 and make measurements a t the measuring polnts shown in
Fig. 15.
Fig. 16 shows an example of differences between the readings of measurlng Instruments used.
However, the measuring instruments having the same measuring accuracy may produce errors
depending on manufacturers, models, and manufacture dates.
Single-phase
power supply
l nverter
Instrument
Ql
Fig. 15 Measur~ng Po~nts and Measuring lnstruments
To motor
:
Inverter output voltage
I
I
Take the ~ndlcated value of rect~f~er type voltmeter as
100%
:
' - _ _ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ,
++
Rect~fler type
c
Mov~ng-~ron type
Therrnoelectr~c type
Fig. 16 Differences of ~nd~cated value w ~ t h varlous rneasurlng Instruments