Hitachi SH1 Series Basic Manual page 113

Chapter 6
6.8 Input/output voltage, current
Standard equipment for measuring input/output voltage,
current, and power measurement.
R
I
R
Power
S
I
Supply S
T
I
T
Measured
Measuring point
data
Input
R-S, S-T,
voltage
(E ), (E ), (E
R S
E
IN
Input R, S,
current (I ), (I ), (I
R S
I
IN
Input power R-S, S-T, T-R
W (W )+(W )+(W
IN I1 I2
Is calculated from the measured values of the input voltage (E
current (I ) and supply power (W
IN
Input power
factor
Pf =
Pf
IN
IN
Output
U-V, V-W, W-U
voltage
(E ), (E ), (E
U V
E
OUT
Output U, V, W current
current (I ), (I ), (I )
U V W
I
OUT
Output U-V, V-W
power (W )+(W )
O1 O2
W
OUT
Is calculated from the measured values of the output voltage (E
Output
current (I
OUT
power
factor
Pf =
OUT
Pf
OUT
Example method for measuring output voltage
R
S
T
Diode
1000V 0.1A or more (400V class)
Effective value of the fundamental wave VAC
VAC＝1.1×VDC
W
I1
E
R
W
I2
E
S
W
I3
E
T
Measuring instrument
T-R
Moving-iron voltmeter or
)
Rectifier-type voltmeter
T
T current
Moving-iron ammeter
)
T
Electrodynamometer-type wattmeter
)
I3
)
IN
W
IN
×100
√3×E ×I
IN IN
Moving-iron voltmeter or
Rectifier-type voltmeter
)
W
Moving-iron ammeter
Electrodynamometer-type wattmeter
) and output power (W ).
OUT
W
OUT
×100
√3×E ×I
OUT OUT
U
V
W
2W 220kΩ
Inspection and maintenance
R U
I
U
Inverter
S V
I
V
T
W
I
W
Remarks
Effective value
of full waves
Effective value
of full waves
Effective value
of full waves
), input
IN
Effective value
of fundamental
wave
Effective value
of full waves
Effective value
of full waves
), output
OUT
Motor
+
VDC
Moving-coil voltmeter
－
600V (400V class)
6-6
U
W
O1
E
U
V
E
V
W
W
O2
E
W
Standard reference values
400V class:380 to 500V 50/60Hz
If there is unbalance in the input
supply
IIN=(I +I + I )/3
R S T
Three-wattmeter method
Two-wattmeter method
(Otherwise the three-wattmeter
method)
When measuring...
1. To measure the output voltage, use an
instrument that reads the effective
value of the fundamental wave. To
measure the current or the power, use
an instrument that reads the effective
value of full waves.
2. Since the inverter output waveform is
controlled by PWM, it has a large
margin of error, especially at low
frequencies. In many cases, general
multimeters may be defective for the
measurement, because of the adverse
effects of the noise.
Motor