Measurement Of Main Circuit Voltages, Currents And Powers - Mitsubishi Electric FR-HC2-7.5K Instruction Manual

5.2

Measurement of main circuit voltages, currents and powers

 Measurement method of voltage and current at each section
When instruments for commercial frequency are used for measurement, measure the following circuits with the instruments
given below.
 When installing meters etc. on the output side of the converter
When the converter-to-motor wiring length is long, especially in the 400V class, the meters may generate heat due to line-
to-line leakage current. Therefore, choose the equipment which has enough allowance for the current rating.
 Voltage is output between the terminal P and N of the converter, and it can be measured using a moving-coil type meter
(tester). The voltage changes by the power supply voltage, but it decreases when a load is applied.
W11
Vu
Power
W12
supply
Vv
W13
Vw
Power
supply
Recommended product :
 Operation principle and application of electric meters
Type
Moving-coil type
Moving-iron meter
Ammeter type Air-core coil
Measurement of main circuit voltages, currents and powers
Outside box
Reactor 1
Au
Filter capacitor
Limit resistor
Av
Inrush current limit MC
Aw
[Examples of Measuring Points and Instruments]
Outside box
Reactor 1
Filter capacitor
Limit resistor
Inrush current limit MC
YOKOGAWA251
DIGITAL POWER METER
(Voltage, current, power, and power factor can be measured.)
[Examples of Measuring Points and Instruments]
Symbol Operation Principle
Uses kinetic power generated
between the magnetic field of
a permanent magnet and the
current that flows through the
moving-coil.
Uses kinetic power generated
between the the moving-iron
and the magnetic field of the
current that flows though the
fixed coil.
Uses kinetic power generated
between the currents that
flow through two different
coils.
Converter
Reactor 2
R4
P/+
/L14
S4
/L24
T4
N/-
/L34
Converter
Reactor 2
R4
P/+
/L14
S4
V
/L24
T4
N/-
/L34
Command Applicable meter
Voltmeter/ammeter/
DC resistance meter/
(average value) thermometer/flux
meter/speed meter
AC
Voltmeter/ammeter
(effective value)
AC/DC Wattmeter/
(effective value) voltmeter/ammeter
+
V
To the Inverter
-
+
To the Inverter
-
Characteristic
High sensitivity and
commonly used.
Energy saving, small
influence of magnetic
field
Strong structure and
inexpensive,
Large influence from
external magnetic
field, frequency, and
waveform
Scale is divided
equally when using a
wattmeter.
Large influence from
external magnetic
field, high energy
consumption
This can be used as a
standard meter for AC
and DC.
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