217
PRECAUTIONS FOR MAINTENANCE AND INSPECTION
6
Measuring Points and Instruments
Note: 1. A tester cannot measure accurately.
2. When Pr. 195 "A, B, C terminal function selection" setting is positive logic.
3. When the carrier frequency exceeds 5kHz, do not use the 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 instrument.
* Values in parentheses indicate those for 400V class.
Item Measuring Point Measuring Instrument
Remarks
(Reference Measured Value) *
Power supply voltage V
1 Across R-S, S-T and T-R Moving-iron type AC voltmeter
Commercial power supply
Within permissible AC voltage
fluctuation (Refer to page 220)
Power supply side
current I
1
R, S and T line currents Moving-iron type AC ammeter
Power supply side power
P
1
At R, S and T, and across R-S,
S-T and T-R
Electrodynamic type single-
phase wattmeter
P1 = W11 + W12 + W13
(3-wattmeter method)
Power supply side power
factor Pf
1
Calculate after measuring power supply voltage, power supply side current and power supply side power.
Output side voltage V
2 Across U-V, V-W and W-U
Rectifier type AC voltmeter
(Note 1) (Not moving-iron type)
Difference between phases is
within ±1% of maximum output
voltage.
Output side current I
2
U, V and W line currents
Moving-iron type AC ammeter
(Note 3)
Current should be equal to or less
than rated inverter current.
Difference between phases is 10%
or lower.
Output side power P
2
At U, V and W, and across U-V
and V-W
Electrodynamic type single-
phase wattmeter
P
2 = W21 + W22
2-wattmeter method
(or 3-wattmeter method)
Output side power factor
Pf
2
Calculate in similar manner to power supply side power factor.
Converter output Across P-N
Moving-coil type (such as
tester)
POWER lamp lit
1.35 × V
1
Maximum 380V (760V) during
regenerative operation
Frequency setting signal
Across 2 (+) -5
Moving-coil type (Tester, etc.
may be used) (Internal
resistance: 50kΩ or larger)
0 to 5V/0 to 10VDC
"5" is
common.
Across 1 (+) -5 0 to ±5V/0 to ±10VDC
Across 4 (+) -5 4 to 20mADC
Frequency setting power
supply
Across 10 (+) -5 5VDC
Across 10E (+) -5 10VDC
Frequency meter signal
Across FM (+) -SD
Approximately 5VDC at
maximum frequency
(without frequency meter)
Pulse width T1:
Adjusted by Pr.900
Pulse cycle T2: Set by Pr.55
(Valid for frequency
monitoring only)
SD is common.
Across AM (+) -5
Approximately 10DVC at
maximum frequency
(without frequency meter)
Start signal
Select signal
Across STF, STR, RH, RM, RL,
JOG, RT, AU, STOP, CS (+) -SD
20 to 30VDC when open.
ON voltage: 1V or lessReset Across RES (+) -SD
Output stop Across MRS (+) -SD
Alarm signal
Across A-C
Across B-C
Moving-coil type
(such as tester)
Continuity check (Note 2)
Across A-C: Discontinuity Continuity
Across B-C: Continuity Discontinuity
Pf
1
= × 100%
P
1
3 V
1
× I
1
Pf
2
= × 100%
P
2
3 V
2
× I
2
8VDC
T1
T2
