364
Measurement of main circuit voltages,
currents and powers
Measuring Points and Instruments
*1 Use an FFT to measure the output voltage accurately. A tester or general measuring instrument cannot measure accurately.
*2 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. If the wiring length between the inverter and motor is long, the instrument and CT may generate
heat due to line-to-line leakage current.
*3 When the setting of Pr. 195 ABC1 terminal function selection is positive logic
*4 A digital power meter (designed for inverter) can also be used to measure.
Item Measuring
Point Measuring Instrument Remarks (Reference Measured Value)
Power supply voltage
V1
Across R/L1and
S/L2, S/L2 and T/
L3, T/L3 and R/
L1
Moving-iron type AC voltmeter *4
Commercial power supply
Within permissible AC voltage fluctuation
Refer to page 370.
Power supply side
current
I1
R/L1, S/L2, and
T/L3 line currents Moving-iron type AC ammeter *4
Power supply side
power
P1
R/L1, S/L2, T/L3 and
R/L1 and S/L2, S/L2
and T/L3, T/L3 and
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.
Output side voltage
V2
Across U and V,
V and W and W
and U
Rectifier type AC voltage meter *1 *4
(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 *2 *4 Difference between the phases is 10% or lower
of the rated inverter current.
Output side power
P2
U, V, W and U
and V, V and 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
Frequency setting
signal
Across 2, 4 (positive)
and 5
Moving-coil type
(Tester and such may be used)
(Internal resistance: 50kΩ or larger)
0 to 10VDC, 4 to 20mA
"5" is
common
Across 1 (positive)
and 5
0 to ±5VDC, 0 to ±10VDC
Frequency setting
power supply
Across 10 (positive)
and 5
5.2VDC
Across 10E (positive)
and 5
10VDC
Frequency meter
signal
Across CA (positive)
and 5
About 20mA at maximum frequency
Across AM (positive)
and 5
Approximately 10DVC at maximum
frequency (without frequency meter)
Start signal
Select signal
Across STF, STR,
RH, RM, RL, JOG,
RT, AU, STOP, CS
and SD (
positive
)
When open
20 to 30VDC
ON voltage: 1V or less
"SD" is
common
Reset
Across RES and SD
(
positive
)
Output stop
Across MRS and SD
(
positive
)
Fault signal
Across A1 and
C1
Across B1 and
C1
Moving-coil type
(such as tester)
Electric continuity check*3
<Normal> <Fault>
Across A1 and C1 Discontinuity Continuity
Across B1 and C1 Continuity Discontinuity
Pf1 = ————— × 100%
P1
3 V1 × I1
Pf2 = ————— × 100%
P2
3 V2 × I2