Hitachi SJ Series, User Manual

Page: 649 / 786

19-7
Chapter 19
Maintenance and Inspection
19.9 Measurement Method of I/O
Voltage, Current, and Power
The following shows general measurement
instruments used for measurement of input/output
voltage, current, and power.
Note)
1. Use an instrument that
indicates effective values of
fundamental wave for output
voltage, and use instruments
that indicate all effective values
for current and power.
2. The output waveform of
inverter generates errors
especially at low frequency
because it is a waveform
control by PWM. Take care
because a tester
(general-purpose product) may
not be adapted due to noise.
Measurement
item
Target section Measurement instrument Remarks Criteria
Power supply
voltage
E
IN
Between R-S, S-T, and T-R
(E
R
), (E
S
), (E
T
)
Moving iron voltmeter
or
Rectifier type voltmeter
All effective values
200V class: 200-240V 50/60Hz
400V class: 380-500V 50/60Hz
Power supply
current
I
IN
Current of R, S, and T
(I
R
), (I
S
), (I
T
)
Moving iron ammeter
All effective values
If input current is imbalanced
I
IN
=(I
R
+I
S
+I
T
)/3
Power from
power supply
W
IN
Between R-S, S-T, and T-R
(W
I1
)+(W
I2
)+(W
I3
)
Electrodynamometer type
wattmeter
All effective values Three wattmeter method
Power rate of
power supply
P
fIN
This value is calculated using measurement values of power supply voltage E
IN
, power
supply current I
IN
, and power supply power W
IN
.
Output
voltage
E
OUT
Between U-V, V-W, and W-U
(E
U
), (E
V
), (E
W
)
See the figure below
or
Rectifier type voltmeter
Effective value of
fundamental wave
Output current
I
OUT
Current of U, V, and W
(I
U
), (I
V
), (I
W
)
Moving iron ammeter
All effective values
Output power
W
OUT
Between U-V and V-W
(W
O1
)+(W
O2
)
Electrodynamometer type
wattmeter
All effective values
Two wattmeter method
(or three wattmeter method)
Output power
factor
P
fOUT
This value is calculated using measurement values of output voltage E
OUT
, output
current I
OUT
, and output power W
OUT
.
Measurement method of output voltage
Diode
600V 0.1A or above (200V class)
1000V 0.1A or above (400V class)
R
T
S
In
v
e
rt
e
r
U
V
W
Motor
Moving coil type
300V (200V class)
600V (400V class)
Effective value of fundamental
wave VAC
VAC=1.1×VDC
+
－
VDC
2W 220kΩ
IR
IS
IT
ER
ET
ES
R
T
S
Inverter
U
V
W
IU
IV
IW
EU
EW
EV
Motor
W
V
U R
S
T
Power
supply
WO1
WO2
WI1
WI2
WI3
P
fOUT
=
W
OUT
√
3
・
E
OUT
・
I
OUT
×100
P
fIN
=
W
IN
√
3
・
E
IN
・
I
IN
×100