Omron 3G3RX - Measurement Methods of I;O Voltage, Current, and Electric Power

6-9
6-1 Inspection and Maintenance
6
Inspection and Maintenance
Measurement Methods of I/O Voltage, Current, and Electric Power
Below is a general measurement device for input/output voltages, current, and electric power.
Power
supply
R
S
T
I
R
I S
I T
E R
E S
E T
W 11
W 12
W 13
R/L1
S/L2
T/L3
U/T1
V/T2
W/T3
Inverter
I U
I V
I W
E U
E V
E W
W 01
W 02
U
V
W
Motor
Measurement
item
Measurement point Measurement device Note Measurement value reference
Power
supply
voltage
E
IN
Between R-S, S-T, and T-
R
(ER), (ES), (ET)
Moving-iron voltmeter
or
Rectifier voltmeter
All
effective
values
200-V class: 200 to 240 V, 50/60 Hz
400-V class: 380 to 480 V, 50/60 Hz
Power
supply
current
I
IN
Current R, S, T
(IR), (IS), (IT)
Moving iron ammeter
All
effective
values
When the input current is not
balanced
I
IN = (IR+IS+ IT)/3
Input
electric
power
W
IN
Between R-S, S-T, and
T-R
(W
I1) + (WI2) + (WI3)
Electrodynamic
wattmeter
All
effective
values
Three-wattmeter method
Input
power
factor Pf
IN
Calculated from the measured values of power supply voltage
E
IN, power supply current IIN, and input electric power WIN.
Output
voltage
E
OUT
Between U-V, V-W, W-U
(EU), (EV), (EW)
See the figure below
or
Rectifier voltmeter
Effective
value of
fundamental
wave
Output
current
I
OUT
Current U, V, W
(IU), (IV),(IW)
Moving iron ammeter
All
effective
values
Output
power
W
OUT
Between U-V, V-W
(W
O1)+(WO2)
Electrodynamic
wattmeter
All
effective
values
Two-wattmeter method
(or three-wattmeter method)
Output
power
factor
Pf
OUT
Calculated from the measured values of output voltage EOUT,
output current IOUT, and output power WOUT.
Pf IN =
3 ⋅ E
IN ⋅ I IN
W IN
× 100(%)
Pf OUT =
3E
OUT I OUT
W OUT
× 100(%)