Delta Electronics VFD-VL manual Power Transmission Mechanism, Motor torque

Appendix C How to Select the Right AC Motor Drive

Power Transmission Mechanism

Pay attention to reduced lubrication when operating gear reduction motors, gearboxes, belts and chains, etc. over longer periods at low speeds. At high speeds of 50/60Hz and above, lifetime reducing noises and vibrations may occur.

Motor torque

The torque characteristics of a motor operated by an AC motor drive and commercial mains power are different.

Below you’ll find the torque-speed characteristics of a standard motor (4-pole, 15kW):

AC motor drive

	180		60 seconds
	155
(%)	140		continuous
torque	100
	80
	55
	38
	0320	60	120
	Frequency (Hz)
	Base freq.: 60Hz
	V/f for 220V/60Hz

	140		60 seconds
(%)	130		continuous
	100
torque	85
	68
	45
	35
	0320	50	120
	Frequency (Hz)
	Base freq.: 50Hz
	V/f for 220V/50Hz

		Motor
	180		60 seconds
	155
(%)			continuous
	100
torque
	55
	38
	0320	60	120
	Frequency (Hz)
	Base freq.: 60Hz
	V/f for 220V/60Hz

	180		60 seconds
	150
(%)			continuous
	100
torque
	80
	45
	35
	03 20	50	120
	Frequency (Hz)
	Base freq.: 50Hz
	V/f for 220V/50Hz

Revision Nov. 2008, VLE1, SW V1.03 C-7