Delta Electronics VFD007S23A Manuel D’Utilisation

Appendix B Accessories|VFD-S Series

Revision August 2006, SE08, SW V2.61

B-5

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

1000V

1300V

1600V

460VAC input voltage

66 ft (20m)

328 ft (100m)

1312 ft (400m)

230VAC input voltage

1312 ft (400m)

For models 5hp/3.7kW and less:

Insulation level of motor

1000V

1300V

1600V

460VAC input voltage

66 ft (20m)

165 ft (50m)

230VAC input voltage

328 ft (100m)

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. 02-03 PWM carrier

frequency).

NOTE

Never connect phase lead capacitors or surge absorbers to the output terminals of the AC motor

drive.