Mitsubishi Electric FR-D720S SC EC, Инструкция по эксплуатации, Страница: 482 / 512

Measurements on the main circuit Maintenance and inspection
8 - 12
Measuring Points and Instruments
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.
Item Measuring Point
Measuring
Instrument
Remarks (Reference Measurement Value)
Power supply
voltage V1 Across
R/L1-S/L2,
S/L2-T/L3,
T/L3-R/L1
Moving-iron type
AC voltmeter Commercial power supply
Within permissible AC voltage fluctuation
(Refer to appendix A)
Power supply
side current I1 R/L1, S/L2, and T/L3
line currents
Moving-iron type
AC ammeter
—
Power supply
side power P1 R/L1, S/L2, T/L3
and R/L1-S/L2,
S/L2-T/L3,
T/L3-R/L1
Digital power
meter (designed
for inverter) or
electrodynamic
type single-phase
wattmeter P1 = W11 + W12 + W13 (3-wattmeter method)
Power supply
side power
factor Pf1 Calculate after measuring power supply voltage, power supply side current and power supply side
power.
Single-phase power supply Three-phase power supply
Output side
voltage V2 Across
U-V, V-W and W-U Rectifier type AC
voltage meter
(Moving-iron type
cannot measure)
Difference between the phases is within ±1% of the
maximum output voltage
Output side
current I2 U, V and W line
currents Moving-iron type
AC ammeter
Difference between the phases is 10% or lower of
the rated inverter current.
Output side
power P2 U, V, W and U-V,
V-W Digital power
meter (designed
for inverter) or
electrodynamic
type single-phase
wattmeter P2 = W21 + W22
2-wattmeter method (or 3-wattmeter method)
Output side
power factor
Pf2 Calculate in similar manner to power supply side power factor.
Converter
output Across P/+ and N/
−
Moving-coil type
(such as tester) Inverter LED display is lit. 1.35
×
V1
Tab. 8-5: Measuring Points and Instruments of the main circuit
Pf1
P1
V1 I1
×
------------------
100 %
× =
Pf1
P1
3 V1 I1
× ×
--------------------------------
100 %
× =
Pf2
P2
3 V2 I2
× ×
--------------------------------
100%
× =