Use Of Ct And Transducer; Measurement Of Inverter Input Power Factor; Measurement Of Converter Output Voltage (Across Terminals P/+ - N/-) - Mitsubishi Electric FR-F740-00023-EC Instruction Manual

4.5.4

Use of CT and transducer

A CT may be used in both the input and output sides of the inverter, but the one used should have the largest possible
VA ability because an error will increase if the frequency gets lower.
When using a transducer, use the effective value calculation type which is immune to harmonics.
4.5.5

Measurement of inverter input power factor

Use the effective power and apparent power to calculate the inverter input power factor. A power-factor meter can not
indicate an exact value.
Total power factor of the inverter
4.5.6

Measurement of converter output voltage (across terminals P/+ - N/-)

The output voltage of the converter is developed across terminals P/+ - N/- and can be measured with a moving-coil
type meter (tester). Although the voltage varies according to the power supply voltage, approximately 540V to 600V is
output when no load is connected and voltage decreases when a load is connected.
When regenerative energy is returned from the motor during deceleration, for example, the converter output voltage
rises to nearly 800V to 900V maximum.
Effective power
=
Apparent power
Three-phase input power found by 3-wattmeter method
=
× V (power supply voltage) × I (input current effective value)
3
Meters and measuring methods
4
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