Measurement Of Current And Voltage In Main Circuit - IMO VXSM75-1 Instruction Manual

8-3 Measurement of Current and
Voltage in Main Circuit
Because the voltage and current of the power
supply (input) of the main circuit of the inverter
and the output (motor) include harmonic
components, the indicated
according to the type of the meter. Use meters
indicated in Table 8-3-1 when measuring with
meters for commercial frequencies.
Marketed power factor meters measuring phase
difference between the voltage and current
cannot measure the power factor. To obtain the
power factor, measure the power, voltage and
Input (power supply) side
Voltage
Ammeter Voltmeter
A V
, ,
R S T
Moving iron Rectifier or
type moving iron
Table 8-3-1 Meters for measurement of main circuit
Note) When the output voltage is measured by a
rectifier type, an error may be included. To increase
the accuracy, use a digital AC power meter.
VXSM***-1
+ -
V
P(+) N(-)
A
W L1/L U
Power
V
V
Supply
L2/N W
8-4
value varies
Current
Wattmeter
W
, , , ,
R S T R S T
Digital Moving iron
power
type meter
A
W
U
U
Motor
V
U
M
A
V
V
V
A
W
W
W
V
W
Fig 8-3-1 Connection of measuring instruments
current on each of the input and output sides
and calculate in the following formula.
In case of Three-phase
In case of Single-phase
Output (motor) side
Voltage
Ammeter Voltmeter
A V
, , , ,
U V W U V W
Rectifier
type type
VXSM***-3
A L1/R
W
R
R
Power
V
Supply R
L2/S
A
S
V
S
A
W L3/T
T
T
V
T
Link voltage
(P(+)-N(-))
Current
Wattmeter DC voltmeter
W V
, ,
U V W
Digital Moving coil
power type
meter
+ -
V
P(+) N(-)
A
U W
U
U
V
U
V A
V
V
V
A
W W
W
W
V
W
Maintenance and Inspection
Motor
M