Methods Of Measuring The Input/Output Voltages, Current, And Power - Hitachi L700 SERIES Instruction Manual

Chapter 6 Maintenance and Inspection

6.9 Methods of Measuring the Input/Output Voltages, Current, and Power

This section describes the measuring instruments generally used to measure the input and output voltages,
output current, and output power of the inverter.
R
S
Power supply
T
Measurement
Measuring point
item
Input voltage (E ) Across R-S, S-T, and T-R
IN
(E ), (E
R
Input current (I ) Current at R, S, and T
IN
(I ), (I
R S
Input power (W ) Across R-S, S-T, and T-R
IN
(W ) + (W
11
input power factor Calculated from the measured input voltage (E
(Pf ) (W )
IN IN
Output voltage Across U-V, V-W, and W-U
(E ) (E ), (E
OUT U
Output current Current at U, V, and W
(I ) (I ), (IV), and (IW)
OUT U
Output power Across U-V and V-W
(W ) (W ) + (W
OUT 01
Output power Calculated from the measured input
factor (Pf ) voltage (E
OUT
and input power (W
Notes:
1. To measure the output voltage, use
an instrument that reads the
effective value of the fundamental
wave. To measure the current or
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
testers may be inapplicable for the
measurement because of the
adverse effect of noise.
W
I
R
E
R
I
W
S
E
S
I W
T
E
T
), and (E )
S T
), and (I )
T
) + (W )
12 13
W
IN
Pf
＝
IN
3・E
IN
), and (EW)
V
)
02
), input current (I ),
OUT OUT
)
OUT
Diode
Effective value of
fundamental wave (V
V
R U
I1
S V
I2
T
W
I3
Measuring instrument
Moving-iron voltmeter
or
rectifier-type voltmeter
Moving-iron ammeter
Electrodynamometer-type
wattmeter
), input current (I
IN
100（％）
・I
IN
Method shown in the figure
below
or
rectifier-type voltmeter
Moving-iron ammeter
Electrodynamometer-type
wattmeter
W
OUT
Pf ＝
OUT
3・E
OUT
Method to measure the output voltage
R U
S V
T W
600 V, 0.1 A or more
(200 V class model)
1,000 V, 0.1 A or more
(400 V class model)
)
AC
= 1.1 x V
AC DC
6 - 6
I W
U
E
U
I
V
E
V
I
W
W
E
W
Remarks Reference values
Effective value of 200 V class models:
full waves 200 to 240 V, 50/60 Hz
400 V class
380 to 480 V, 50/60 Hz
Effective value of When input currents are
full waves unbalanced
I = (I
IN
Effective value of 3-wattmeter method
full waves
), and input power
IN
Effective value of
fundamental wave
Effective value of
full waves
Effective value of 2-wattmeter method
full waves (or 3-wattmeter method)
100（％）
・I
OUT
2W 220ｋ
+
V
－ Moving-coil voltmeter
300 V (200 V class
model)
600 V (400 V class
model)
U
O1
V
Motor
W
O2
+ I + I )/3
R S T
Motor
DC