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Cable Length Between Drive and Motor

When the wiring between the drive and the motor is too long, voltage drop along the motor cable can decrease motor torque, usually at low frequency output. If you connect motors in parallel with long motor cable, this is also a problem. Drive output current increases when the leakage current from the cable increases. An increase in leakage current can cause overcurrent and decrease the precision of the current detection.

Use the values in Table 1 to adjust the drive carrier frequency. For systems that have 100 m (328 ft) or longer motor wiring, if you use metal conduits or isolated cables for each phase, it will increase stray capacitance.

Table 1. Carrier Frequency against Cable Length Between Drive and Motor

Wiring Distance Between the Drive and Motor

50 m (164 ft) Maximum

100 m (328 ft) Maximum

More than 100 m (328 ft)

Carrier Frequency

15 kHz or less

5 kHz or less

2 kHz or less
Note:

  • To set the carrier frequency in a drive that is operating more than one motor, calculate the cable length as the total distance of wiring to all connected motors.

  • If the length of the wire between the drive and an induction motor is longer than 100 m (328 ft), set A1-02 = 0[V/f].

  • The maximum cable length between the drive and a PM motor is 100 m (328 ft).

  • If the cable length between the drive and the motor is too long when A1-02 = 6 [AOLV/PM] or 8 [EZOLV], change the setting to A1-02 = 5 [OLV/PM].

  • When you connect to a PM motor, it can be necessary to adjust the overcurrent detection. Refer to L8-27: Overcurrent Detection Gain for more information.