General Inverter Electrical Measurements - Hitachi WJ200 Series Instruction Manual

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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.
Parameter
Supply voltage
E
1
Supply current
I
1
Supply power
W
1
Supply power
factor Pf
1
Output voltage
E
O
Output current
I
O
Output power
W
O
Output power
factor Pf
O
Note 1:
Note 2:
Note 3:
Circuit location of
measurement
E – across L1 and L2
R
E – across L2 and L3
S
E – across L3 and L1
T
Single phase
E – across L1 and N
1
I – L1
r
I – L2
s
I – L3
t
Single phase
I = L1
1
W – across L1 and L2
11
W – across L2 and L3
12
Single phase
W – across L1 and N
1
=
Pf
1
E – across U and V
U
E – across V and W
V
E – across W and U
W
I – U
U
I – V
V
I – W
W
W – across U and V
O1
W – across V and W
O2
Calculate the output power factor from the output voltage E,
output current I, and output power W.
=
Pf
O
Use a meter indicating a fundamental wave effective value for voltage, and meters
indicating total effective values for current and power.
The inverter output has a distorted waveform, and low frequencies may cause
erroneous readings. However, the measuring instruments and methods listed above
provide comparably accurate results.
A general-purpose digital volt meter (DVM) is not usually suitable to measure a
distorted waveform (not pure sinusoid).
Measuring
instrument
Moving-coil type Fundamental
voltmeter or wave effective
rectifier type value
voltmeter
Total effective
value
Total effective
value
W
×
1
100 %
× ×
3 E I
1 1
Rectifier type Total effective
voltmeter value
Moving-coil type Total effective
ammeter value
Electronic type Total effective
wattmeter value
W
×
1
100 %
× ×
3 E I
O O
Notes Reference Value
Commercial supply
voltage
200V class:
200–240V, 50/60 Hz
400V class:
380–460V, 50/60 Hz
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