The Length Of Motor Cable - Delta Electronics AC Motor Drive VFD-VE Series User Manual

The length of motor cable

When motor is driven by an AC motor drive of PWM type, the motor terminals will experience surge
voltages easily due to components conversion of AC motor drive and cable capacitance. When the
motor cable is very long (especially for the 460V series), surge voltages may reduce insulation
quality. To prevent this situation, please follow the rules below:
Use a motor with enhanced insulation.
Connect an output reactor (optional) to the output terminals of the AC motor drive
The length of the cable between AC motor drive and motor should be as short as possible
(10 to 20 m or less)
For models 7.5hp/5.5kW and above:
Insulation level of motor
460VAC input voltage
230VAC input voltage
For models 5hp/3.7kW and less:
Insulation level of motor
460VAC input voltage
230VAC input voltage
NOTE
When a thermal O/L relay protected by motor is used between AC motor drive and motor, it may
malfunction (especially for 460V series), even if the length of motor cable is only 165 ft (50m) or less.
To prevent it, please use AC reactor and/or lower the carrier frequency (Pr. 00-17 PWM carrier
frequency).
NOTE
Never connect phase lead capacitors or surge absorbers to the output terminals of the AC motor
drive.
Revision August 2008, 03VE, SW V2.04
1000V
66 ft (20m) 328 ft (100m)
1312 ft (400m) 1312 ft (400m)
1000V
66 ft (20m) 165 ft (50m)
328 ft (100m) 328 ft (100m)
Appendix B Accessories|
1300V 1600V
1312 ft (400m)
1312 ft (400m)
1300V 1600V
165 ft (50m)
328 ft (100m)
B-31