Delta VFD-ED Series, User Manual

Page: 99 / 389

06 Optional Accessories | VFD-ED
6-48
The motor cable length
1. Required cable length when the motor drive is at full load.
a. Non-shielded cable: For 5.5 kW (7.5 HP) and below models, the maximum cable length is 100 m
(328 ft). For 7.5 kW (10 HP) and above models, the maximum cable length is 200 m (656 ft)
b. Shielded cable: For 5.5 kW (7.5 HP) and below models, the maximum cable length is 50 m (165 ft).
For 7.5 kW (10 HP) models, the maximum cable length is 100 m (328 ft).
c. To be compatible with the European Standards EN12015 & EN12016, follow one of the following
in addition to the precautions on page 6-44:

Use shielded cables

The motor cable must be shorter than 2 m (6 ft).
If the cable length is longer than the recommended lengths above, install an output reactor.
NOTE
 If the cable length is too long, the stray capacitance between cables increases and may
cause leakage current. In this case, It activates the over-current protection, increases
leakage current, or may affect the current display. The worst case is that it may damage the
AC motor drive.

If more than one motor is connected to the AC motor drive, the total wiring length is the sum
of the wiring length from AC motor drive to each motor.
 For the 460V series AC motor drive, when you install an overload thermal relay between the
drive and the motor to protect the motor from overheating, the connecting cable must be
shorter than 50 m; however, an overload thermal relay malfunction may still occur. To
prevent the malfunction, install an output reactor (optional) to the drive or lower the carrier
frequency setting (Pr.00-12).
2. Consequence of the surge voltages on the motor
When a motor is driven by a PWM-type AC motor drive, the motor terminals experience surge voltages
due to component conversion of AC motor drive and cable capacitance. When the motor cable is very
long (especially for the 460V series), surge voltages may damage the insulation. To prevent this, follow
these rules:
a. Use a motor with enhanced insulation (refer to the tables below).
b. Reduce the cable length between the AC motor drive and motor to suggested values.
c. Connect an output reactor (optional) to the output terminals of the AC motor drive.
For 7.5 kW (10 HP) and higher models:
Insulation level of motor 1000 V 1300 V 1600 V
460 V
AC
input voltage 20 m (66 ft) 100 m (328 ft) 400 m (1312 ft)
230 V
AC
input voltage 400 m (1312 ft) 400 m (1312 ft) 400 m (1312 ft)
For 5.5 kW (7.5 HP) and lower models:
Insulation level of motor 1000 V 1300 V 1600 V
460 V
AC
input voltage 20 m (66 ft) 50 m (165 ft) 50 m (165 ft)
230 V
AC
input voltage 100 m (328 ft) 100 m (328 ft) 100 m (328 ft)