Hitachi L100 General Inverter Electrical Measurements

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Maintenance and Inspection

Troubleshooting and Maintenance

General Inverter Electrical Measurements

The following table specifies how to measure key system electrical parameters. The diagrams on the next page show inverter-motor systems and the location of measurement points for these parameters.

Parameter			Circuit location		Measuring	Notes	Reference Value
			of measurement		instrument
Supply voltage	ER – across L1 and L2				Moving-coil	Fundamental	Commercial
E1	ES – across L2 and L3				type voltmeter or	wave effective	supply voltage
	ET – across L3 and L1				rectifier type	value	(200V class) 200–
					voltmeter		240V, 50/60 Hz
							400V class 380–
							460V, 50/60 Hz
Supply current	Ir – L1, Is – L2, It – L3					Total effective	—
I1						value
Supply power	W11 – across L1 and L2					Total effective	—
W1	W		– across L2 and L3			value
		12
Supply power			Pf1 =		W1		—
factor Pf1
				----------------------------- ⋅ 100%
				3	⋅ E1 ⋅ I1
Output voltage	EU – across U and V				Rectifier type	Total effective	—
E0	E		– across V and W		voltmeter	value
	V
	EW – across W and U
Output current	IU – U				Moving-coil	Total effective	—
Io	I	– V			ammeter	value
	V
	IW – W
Output power	W01 – across U and V				Electronic type	Total effective	—
Wo	W		– across V and W		wattmeter	value
		02
Output power	Calculate the output power factor from the output voltage E,						—
factor Pfo	output current I, and output power W.
			Pf0 =		W0
				----------------------------- ⋅ 100%
				3	⋅ E0 ⋅ I0

Note 1: Use a meter indicating a fundamental wave effective value for voltage, and meters indicating total effective values for current and power.

Note 2: The inverter output has a distorted waveform, and low frequencies may cause erroneous readings. However, the measuring instruments and methods listed above provide comparably accurate results.

Note 3: A general-purpose digital volt meter (DVM) is not usually suitable to measure a distorted waveform (not pure sinusoid).