Filter
Top Products
SJ300 Inverter
Troubleshooting
and Maintenance
6–15
General Inverter
Electrical
Measurements
The following table specifies how to measure key system electrical parameters. The diagrams
on the next page show inverter-motor systems and the location of measurement points for these
parameters.
Note 1: Use a meter indicating a fundamental wave effective value for voltage, and meters
indicating total effective values for current and power.
Note 2: The inverter output has a distorted waveform, and harmonic frequencies may cause
erroneous readings. However, the measuring instruments and methods listed above
provide reasonably accurate results.
Note 3: A general-purpose digital volt meter (DVM) is not usually suitable to measure a
distorted waveform (not pure sinusoid).
Parameter
Circuit location
of measurement
Measuring
instrument
Notes Reference Value
Supply voltage
E
1
E
R
– across L1 and L2
E
S
– across L2 and L3
E
T
– across L3 and L1
Moving-coil type
voltmeter or recti-
fier type voltmeter
Fundamental
wave effective
value
Commercial supply
voltage (200V class)
200-240V, 50/60 Hz
400V class 380-
460V, 50/60 Hz
Supply current
I
1
I
r
– L1, I
s
– L2, I
t
– L3 Moving-coil type
ammeter
Total effective
value
—
Supply power W
1
W
11
– across L1 and L2
W
12
– across L2 and L3
Electronic type
wattmeter
Total effective
value
—
Supply power
factor Pf
1
—
Output voltage
E
0
E
U
– across U and V
E
V
– across V and W
E
W
– across W and U
Rectifier type
voltmeter
Total effective
value
—
Output current I
o
I
U
– U
I
V
– V
I
W
– W
Moving-coil type
ammeter
Total effective
value
—
Output power W
o
W
01
– across U and V
W
02
– across V and W
Electronic type
wattmeter
Total effective
value
—
Output power
factor Pf
o
Calculate the output power factor from the output voltage E, output
current I, and output power W.
—
Pf
1
W
1
3E
1
× I
1
×
------------------------------
100%×=
Pf
0
W
0
3E
0
× I
0
×
------------------------------
100%×=