PROTECTIVE FUNCTIONS
185
Measuring Points and Instruments
Item
Measuring Point
Measuring Instrument
Remarks
(Reference Measured Value)
Power supply
voltage
(V1)
Across L
1
-L
2
, L
2
-L
3
, L
3
-L
1
Moving-iron type AC
voltmeter
Is the commercial power supply
within permissible variation of AC
voltage (Refer to page 186)
Power supply side
current
(I1)
L
1
, L
2
and L
3
line currents
Moving-iron type AC
ammeter
Power supply side
power
(P1)
At L
1
, L
2
and L
3
, and across
L
1
-L
2
, L
2
-L
3
and L
3
-L
1
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.
[For three-phase power supply]
[For single-phase power supply]
Pf1= 100%
3V
1
I
1
P
1
Pf1= 100%
V
1
I
1
P
1
Output side
voltage
(V2)
Across U-V, V-W and W-U
(Note 1)
(Cannot be measured
by moving-iron type)
Difference between phases is within
±
1% of maximum output voltage.
Output side current
(I2)
U, V and W line currents
Moving-iron type AC
ammeter
(Note 2)
Current should be equal to or less than
rated inverter current.
Difference between phases is 10% or
lower.
Output side power
(P2)
At U, V and W, and across U-
V and V-W
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.
Pf2= 100%
3V
2
I
2
P
2
Converter output
-
−
Moving-coil type
(such as tester)
Inverter LED display is lit. 1.35
×
V1
Maximum 760V (380V) during
regenerative operation
Across 2 (positive)-5
0 to 5V/0 to 10VDC
Frequency setting
signal
Across 4 (positive)-5
4 to 20mADC
Frequency setting
power supply
Across 10 (positive)-5
5VDC
Frequency meter
signal
Across AM (positive)-5
Moving-coil type
(Meter, etc. may be
used)
(Internal resistance:
50k
Ω
or larger)
Approximately 10VDC at
maximum frequency (without
frequency meter)
"5" is common.
Start signal
Select signal
Across STF, STR, RH, RM,
RL, MRS, RES-SD
Reset
Across RES (positive)-SD
Output stop
Across MRS (positive)-SD
Moving-coil type
(Meter, etc. may be
used)
(Internal resistance:
50k
Ω
or larger)
20 to 30VDC when open.
ON voltage: 1V or less
SD is
common.
Alarm signal
Across A-C
Across B-C
Moving-coil type
(such as a meter)
Continuity check
<Normal>
<Fault>
Across A-C: Discontinuity Continuity
Across B-C: Continuity
Discontinuity
Note: 1. Use FFT to measure the output voltage accurately. It can not be measured accurately with a meter or
general instrumentation.
2. If the carrier frequency exceeds 5kHz, do not use this instrument since using it may increase eddy-
current loss produced in metal parts inside the instrument, leading to burnout.
In this case, use an approximate effective value type instrument.
*The value within the parentheses is for the 200V class.