Chapter 7 Optional AccessoriesC2000 Plus
7-57
Motor Cable Length
1. Consequence of leakage current on the motor
If the cable length is too long, the stray capacitance between cables increase 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 one AC motor drive, the total wiring length should be 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 (see Pr.00-17
Carrier Frequency).
2. Consequence of the surge voltage on the motor
When a motor is driven by a PWM-type AC motor drive, the motor terminals experience surge
voltages (dv/dt) due to power transistor conversion of AC motor drive. When the motor cable is very
long (especially for the 460V series), surge voltages (dv/dt) may damage the motor insulation and
bearing. To prevent this, follow these rules:
a. Use a motor with enhanced insulation.
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
Refer to the following tables for the suggested motor shielded cable length. Use a motor with a
rated voltage ≤ 500 V
AC
and insulation level ≥ 1.35 kV in accordance with IEC 60034-17.
230V Models
Rated current
(HD, Arms)
Without an AC output reactor With an AC output reactor
Shielded Cable
(meter)
Non-shielded
cable (meter)
Shielded Cable
(meter)
Non-shielded
cable (meter)
VFD007C23A-21 5 50 75 75 115
VFD015C23A-21 8 50 75 75 115
VFD022C23A-21 11 50 75 75 115
VFD037C23A-21 17 50 75 75 115
VFD055C23A-21 25 50 75 75 115
VFD075C23A-21 33 100 150 150 225
VFD110C23A-21 49 100 150 150 225
VFD150C23A-21 65 100 150 150 225
VFD185C23A-21 75 100 150 150 225
VFD220C23A-21 90 100 150 150 225
VFD300C23A-00
VFD300C23A-21
120 100 150 150 225
VFD370C23A-00
VFD370C23A-21
146 100 150 150 225
VFD450C23A-00
VFD450C23A-21
180 150 225 225 325
VFD550C23A-00
VFD550C23A-21
215 150 225 225 325
VFD750C23A-00
VFD750C23A-21
255 150 225 225 325
VFD900C23A-00
VFD900C23A-21
346 150 225 225 325
Table 7-63
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