Instruction manual

187
6
MAINTENANCE/INSPECTION
Measuring Points and Instruments
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.
Item Measuring Point Measuring Instrument
Remarks
(Reference Measured Value)
Power supply
voltage
(V1)
Across R-S (L
1-L2), S-T (L2-
L
3) and T-R (L3-L1)
Moving-iron type AC
voltmeter
Is the commercial power supply within
permissible variation of AC voltage
(Refer to page 190)
Power supply side
current
(I1)
R, S and T line currents
(L
1, L2 and L3 line currents)
Moving-iron type AC
ammeter
Power supply side
power
(P1)
At R (L
1), S (L2) and T (L3),
and across R-S (L
1-L2), S-T
(L
2-L3) and T-R (L3-L1)
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]
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.
Converter output Across P-N (+ - –)
Moving-coil type
(such as tester)
Inverter LED display is lit. 1.35
× V1
Maximum 923V during regenerative
operation
Frequency setting
signal
Across 2 (positive)-5
Moving-coil type
(Meter, etc. may be used)
(Internal resistance:
50
Ω or larger)
0 to 5V/0 to 10VDC
"5" is
common.
Across 4 (positive)-5 4 to 20mADC
Frequency setting
power supply
Across 10 (positive)-5 5VDC
Frequency meter
signal
Across AM (+)-5
Approximately 10DVC at
maximum frequency (without
frequency meter)
Start signal
Select signal
Across STF, STR, RH, RM,
RL, MRS, RES-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.
Reset Across RES (positive)-SD
Output stop Across MRS (positive)-SD
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
Pf1=
P1
3V I1
100%
Pf2=
P2
3V2 I2
100%
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