Fuji Electric FRENIC-AQUA series, User Manual

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10-8
10.4 Measurement of Electrical Amounts in Main Circuit
Because the voltage and current of the power supply (input, primary circuit) of the inverter main
circuit and those of the motor (output, secondary circuit) contain harmonic components, the readings
may vary with the type of the meter. Use meters listed in Table 10.4 when measuring with meters
designed for commercial frequencies.
The power factor cannot be measured by a commercially available power-factor meter that measures
the phase difference between the voltage and current. To obtain the power factor, measure the power,
voltage and current on each of the input and output sides and use the following formula.
„ Three-phase input
% 100 ×
(A) Current × (V) Voltage × 3
(W) power Electric
= factor Power
Table 10.4 Meters for Measurement of Main Circuit
Item
Input (primary) side Output (secondary) side
DC link bus
voltage
(P(+)-N(-))
W
av
efo
rm
Voltage Current Voltage Current
Name o
f
meter
Ammeter
A
R
, A
S
, A
T
Voltmeter
V
R
, V
S
, V
T
Wattmeter
W
R
, W
T
Ammeter
A
U
, A
V
, A
W
Voltmeter
V
U
, V
V
, V
W
Wattmeter
W
U
, W
W
DC voltmeter
V
Type
o
f
meter
Moving iron
type
Rectifier or
moving iron
type
Digital AC
power meter
Digital AC
power meter
Digital AC
power meter
Digital AC
power meter
Moving coil
type
Sym
bol
of
met
er
⎯ ⎯ ⎯ ⎯
It is not recommended that meters other than a digital AC power meter be used for measuring
the output voltage or output current since they may cause larger measurement errors or, in the
worst case, they may be damaged.
Figure 10.1 Connection of Meters