Hitachi SJ700-2 instruction manual PfIN＝, Method to measure the output voltage, Motor 2W 220ｋΩ

Chapter 6 Maintenance and Inspection

6.8 Methods of Measuring the Input/Output Voltages, Current, and Power

This section describes the measuring instruments generally used to measure the input and output voltages, output current, and output power of the inverter.

R IR

Power supply S IS

WI1

ER

WI2

ES

R	Inverter	U	IU
S		V	IV

WO1 U

EU

V

EV

Motor

T IT

WI3

ET

T	W	W
		I

W

WO2

EW

Measurement	Measuring point			Measuring instrument				Remarks		Reference values
item
Input voltage (EIN)	Across R-S, S-T, and T-R			Moving-iron voltmeter				Effective value of		200 V class models:
	(ER), (ES), and (ET)			or				full waves		200 to 240 V, 50/60 Hz
				rectifier-type voltmeter						400 V class
										380 to 480 V, 50/60 Hz
Input current (IIN)	Current at R, S, and T			Moving-iron ammeter				Effective value of		When input currents are
	(IR), (IS), and (IT)							full waves		unbalanced
										IIN = (IR + IS + IT)/3
Input power (WIN)	Across R-S, S-T, and T-R			Electrodynamometer-type				Effective value of		3-wattmeter method
	(W11) + (W12) + (W13)			wattmeter				full waves
input power factor	Calculated from the measured input voltage (EIN), input current (IIN), and input power
(PfIN)	(WIN)		WIN
	PfIN＝				×100（％）
		√3・EIN・IIN
Output voltage	Across U-V, V-W, and W-U			Method shown in the figure				Effective value of
(EOUT)	(EU), (EV), and (EW)			below				fundamental wave
				or
				rectifier-type voltmeter
Output current	Current at U, V, and W			Moving-iron ammeter				Effective value of
(IOUT)	(IU), (IV), and (IW)							full waves
Output power	Across U-V and V-W			Electrodynamometer-type				Effective value of		2-wattmeter method
(WOUT)	(W01) + (W02)			wattmeter				full waves		(or 3-wattmeter method)
Output power	Calculated from the measured input				PfOUT＝		WOUT		×100（％）
factor (PfOUT)	voltage (EOUT), input current (IOUT),
	and input power (WOUT)					√3・EOUT・IOUT

Notes:

Method to measure the output voltage

1.To measure the output voltage, use an instrument that reads the effective value of the fundamental wave. To measure the current or power, use an instrument that reads the effective value of full waves.

2.Since the inverter output waveform is controlled by PWM, it has a large margin of error, especially at low frequencies. In many cases, general testers may be inapplicable for the measurement because of the adverse effect of noise.

RU

SInverter V

TW

Diode

600 V, 0.1 A or more

(200 V class model)

1,000 V, 0.1 A or more

(400 V class model)

Effective value of fundamental wave (VAC) VAC = 1.1 x VDC

Motor

2W 220ｋΩ

+

VDC

－ Moving-coil voltmeter 300 V (200 V class model)

600 V (400 V class model)

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