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

Appendix C How to Select the Right AC Motor Drive

5.Synchronous motor:

The rated current and starting current are higher than for standard motors. Please check before operation and choose the capacity of the AC motor drive carefully. When the AC motor drive operates more than one motor, please pay attention to starting and changing the motor.

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 Motor

	180		60 seconds
	155
(%)	140
torque	100
	80
	55
	38
	03 20	60	120
	Frequency (Hz)
	Base freq.: 60Hz
	V/f for 220V/60Hz

	140		60 seconds
(%)	130
	100
	85
torque
	68
	45
	35
	03 20	50	120
	Frequency (Hz)
	Base freq.: 50Hz
	V/f for 220V/50Hz

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

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

Revision July 2008, EG03, SW V1.06 C-7