Hitachi SJ700-2 instruction manual 17 V/F characteristic curve selection, VPf

Chapter 4 Explanation of Functions

4.2.17 V/F characteristic curve selection

The V/F characteristic curve selection function allows you to set the output voltage/output frequency (V/f) characteristic.

To switch the V/F characteristic curve selection among the 1st, 2nd, and 3rd settings, assign function "08" (SET) and "17" (SET3) to intelligent input terminals. Use the SET and SET3 signals for switching.

Related code

A044/A244/A344: V/F characteristic curve selection, 1st/2nd/3rd motors b100/b102/b104/b106/b108/b110/b112: Free-setting V/f frequency (1) (2) (3) (4) (5) (6) (7) b101/b103/b105/b107/b109/b111/b113: Free-setting V/f voltage (1) (2) (3) (4) (5) (6) (7)

Function code	Data	V/f characteristic	Remarks
	00	Constant torque characteristic (VC)
	01	Reduced-torque characteristic
		(1.7th power of VP)
A044/A244/	02	Free V/f characteristic	Available only for A044 and A244
		Sensorless vector control (SLV)	Available only for A044 and A244 (See Section
A344	03
			4.2.96.)
	04	0 Hz-range sensorless vector	Available only for A044 and A244 (See Section
		control	4.2.97.)
	05	Vector control with sensor (V2)	Available only for A044

(1) Constant torque characteristic (VC)

With this control system set, the output voltage is in proportion to the output frequency within the range from 0 Hz to the base frequency. Within the output frequency range over the base frequency up to the maximum frequency, the output voltage is constant, regardless of the change in the output frequency.

Output voltage (100%)

Output frequency (Hz)

0	Base	Maximum
	frequency	frequency

(2) Reduced-torque characteristic (1.7th power of VP)

This control system is suited when the inverter is used with equipment (e.g., fan or pump) that does not require a large torque at a low speed.

Since this control system reduces the output voltage at low frequencies, you can use it to increase the efficiency of equipment operation and reduce the noise and vibrations generated from the equipment. The V/f characteristic curve for this control system is shown below.

Output voltage (100%)

			VC				VP(f1.7)
			0	base					Output frequency (Hz)
			10% of			Base		Maximum
			frequency			frequency		frequency
			a		b			c
Period	a	:	While the output frequency increases from 0 Hz to the 10% of the base frequency, the
			output voltage follows the constant torque characteristic.
			(Example) If the base frequency is 60 Hz, the constant torque characteristic is maintained
			within the output frequency range of 0 to 60 Hz.
Period	b	:	While the output frequency increases from the 10% of base frequency to the base
			frequency, the output voltage follows the reduced-torque characteristic. In other words, the
			output voltage increases according to the 1.7th power of the output frequency.
Period	c	:	While the output frequency increases from the base frequency to the maximum frequency,
			the output voltage is constant.
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