B-44
Choose suitable motor cable and precautions
Improper installation and choice of motor cable will affect the performance of EMI filter. Be sure to
observe the following precautions when selecting motor cable.
1. Use the cable with shielding (double shielding is the best).
2. The shielding on both ends of the motor cable should be grounded with the minimum length and
maximum contact area.
3. Remove any paint on metal saddle for good ground contact with the plate and shielding.
Remove any paint on metal saddle for good ground contact with
the plate and shielding.
saddle
the plate with grounding
Saddle on both ends
Saddle on one end
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)
1312 ft (400m)
1312 ft (400m)
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:
