Use Of Ct And Transducer; Measurement Of Inverter Input Power Factor; Measurement Of Converter Output Voltage (Across Terminals + And -) - Mitsubishi Electric FR-E700 Instruction Manual

Troubleshooting
7.7.4

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 harmon-
ics.
7.7.5

Measurement of inverter input power factor

Use the effective power and apparent power to calculate the inverter input power factor. A
power-factor meter cannot indicate an exact value.
Total power factor of the inverter
7.7.6 Measurement of converter output voltage (across terminals + and –)
The output voltage of the converter is developed across terminals + and – and can be measured
with a moving-coil type meter (tester). Although the voltage varies according to the power supply
voltage, approximately 270VDC to 300VDC (540VDC to 600VDC for the 400V class) is output
when no load is connected and voltage decreases during driving load operation.
When energy is regenerated from the motor during deceleration, for example, the converter out-
put voltage rises to nearly 400VDC to 450VDC (800VDC to 900VDC for the 400V class) max-
imum. When this value is reached the alarm message E.OV is displayed and the inverter out-
put is shut off.
FR-E700 EC
Effective power
= ----------------------------------------- -
Apparent power
3-phase input power found by 3-wattmeter method
= ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
×
3 V (power supply voltage)
Meters and measuring methods
×
I (input current effective value)
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