Mitsubishi Electric FR-D720S SC EC Instruction Manual page 482

Measurements on the main circuit
Measuring Points and Instruments
Item
Power supply
voltage V1
Power supply
side current I1
Power supply
side power P1
Power supply
side power
factor Pf1
Output side
voltage V2
Output side
current I2
Output side
power P2
Output side
power factor
Pf2
Converter
output
Tab. 8-5: Measuring Points and Instruments of the main circuit
Use an FFT to measure the output voltage accurately. An FA tester or general measuring
instrument cannot measure accurately.
When the carrier frequency exceeds 5kHz, do not use this instrument since using it may
increase eddy-current losses produced in metal parts inside the instrument, leading to
burnout. In this case, use an approximate-effective value type.
T/L3 is only for the three-phase power input specification models.
A digital power meter (designed for inverter) can also be used to measure.
8 - 12
Measuring
Measuring Point
Instrument
Across Moving-iron type
R/L1-S/L2, AC voltmeter
S/L2-T/L3,
T/L3-R/L1
R/L1, S/L2, and T/L3 Moving-iron type
AC ammeter
line currents
R/L1, S/L2, T/L3 Digital power
and R/L1-S/L2, meter (designed
S/L2-T/L3, for inverter) or
electrodynamic
T/L3-R/L1
type single-phase
wattmeter
Calculate after measuring power supply voltage, power supply side current and power supply side
power.
Single-phase power supply
P1
----------------- -
×
Pf1 100 %
×
V1 I1
Across Rectifier type AC
U-V, V-W and W-U
voltage meter
(Moving-iron type
cannot measure)
U, V and W line Moving-iron type
currents
AC ammeter
U, V, W and U-V, Digital power
V-W meter (designed
for inverter) or
electrodynamic
type single-phase
wattmeter
Calculate in similar manner to power supply side power factor.
P2
------------------------------- -
×
Pf2 100%
× ×
3 V2 I2
Across P/+ and N/− Moving-coil type
(such as tester)
Maintenance and inspection
Remarks (Reference Measurement Value)
Commercial power supply
Within permissible AC voltage fluctuation
(Refer to appendix A)
—
P1 = W11 + W12 + W13 (3-wattmeter method)
Three-phase power supply
P1
------------------------------- -
×
Pf1 100 %
× ×
3 V1 I1
Difference between the phases is within ±1% of the
maximum output voltage
Difference between the phases is 10% or lower of
the rated inverter current.
P2 = W21 + W22
2-wattmeter method (or 3-wattmeter method)
Inverter LED display is lit. 1.35 × V1