Use Of Ct And Transducer; Measurement Of Inverter Input Power Factor; Measurement Of Converter Output Voltage (Across Terminals P/+ - N/-) - Mitsubishi Electric F700 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). Varying with the power supply voltage, the converter output voltage is approximately 270 to
300V (approximately 540 to 600V for the 400V class) under no load and lowers under load. When regenerative
energy is returned from the motor during deceleration, for example, the converter output voltage rises to nearly
400V (800V for the 400V class) maximum. (When the converter output voltage reaches approximately 800V for the
400V class, the inverter results in OV
Effective power
=
Apparent power
3-phase input power found by 3-wattmeter method
=
× V (power supply voltage) × I (input current effective value)
3
shut-off)
Meters and measuring methods
4
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