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7.2
Measurement of main circuit voltages, currents,
and powers
Since the voltages and currents on the converter unit power supply and output sides include harmonics, measurement data
depends on the instruments used and circuits measured. When instruments for commercial frequency are used for
measurement, measure the following circuits with the instruments given on the next page.
NOTE
• When installing meters etc. on the output side of the converter unit:
When the wiring length between the converter unit and the inverter is long, 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.
Measuring points and instruments
Item
Power supply voltage
V1
Input current
I1
Input power
P1
Input power factor
Pf1
Converter output
Input signal
Fault signal
*1
When the setting of Pr.195 ABC1 terminal function selection is the positive logic.
172
7. PRECAUTIONS FOR MAINTENANCE AND INSPECTION
7.2 Measurement of main circuit voltages, currents, and powers
Ar
Vr
Three-phase
As
power supply
Vs
At
Vt
Measuring point
Between R/L1 and S/L2,
S/L2 and T/L3, and T/L3
and R/L1
Line current at R/L1, S/L2,
and T/L3
At R/L1, S/L2, and T/L3,
and between R/L1 and S/
L2, S/L2 and T/L3, and T/
L3 and R/L1
Calculate after measuring input voltage, input current and input power.
P
1
Pf
=
x 100%
1
I
x
3V
1
1
Between P/+ and N/-
Across terminals RDI, OH,
RES(+) and SD (for sink
logic)
Between A1 and C1
Between B1 and C1
Input voltage
Input current
Converter unit
P/+
R/L1
W11
S/L2
W12
N/-
T/L3
W13
Measuring instrument
Digital power meter (designed for
inverter)
Tester such as a digital
multimeter.
Tester such as a digital
multimeter, or moving-coil type
instrument (internal resistance
50 kΩ or more)
Digital multimeter or other tester
+
To the inverter
V
-
Remarks (reference measured value)
Commercial power
Within permissible AC voltage fluctuation. (Refer to
page
176.)
P1 = W11 + W12 + W13 (3-wattmeter method)
Inverter LED indication 1.35 × V1
Voltage when terminal is open: 20 to
30 VDC.
Voltage when signal is ON: 1 V or
less.
*1
Continuity test
Normal: discontinuity across A1 and C1 (continuity
across B1 and C1)
Fault: continuity across A1 and C1 (discontinuity
across B1 and C1)
Terminal SD
is a common
terminal.
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