Output Filters : dv/dt filters

Variable speed drives
Altivar Process
Option: Output filters
dv/dt filters

Altivar Process drives with supply voltages of 200...240 V and 380...480 V operate with the following maximum motor cable lengths: 150 m/492 ft for shielded cables and 300 m/984 ft for unshielded cables. For a supply voltage of 500...690 V, maximum motor cable lengths are: 10 m/32 ft for shielded cables and 20 m/65 ft for unshielded cables.

To limit the impact of dv/dt and overvoltages in the motor, it is advisable to add an output filter if the motor insulation type does not conform to IEC 600034-25:

• For cables <50 m/164.04 ft, a dv/dt output filter
• For cables >50 m/164.04 ft, a sinus filter

Output filters are used to limit dv/dt at the motor terminals to 500 V/μs maximum for supply voltages up to 480 V, to 750 V/μs maximum for a supply voltage of 500 V, and to 1,000 V/μs maximum for a supply voltage of 690 V.

Output filters are designed to limit overvoltages at the motor terminals to less than:

• 800 V with a shielded cable 0 to 50 m (0 to 164 ft) long for a 400 V supply voltage
• 1,000 V with a shielded cable 50 to 150 m (164 to 492 ft) long for a 400 V supply voltage
• 1,500 V with a shielded cable 150 to 300 m (492 to 984 ft) long for a 400 V supply voltage (up to 500 m (1,640 ft) with an unshielded cable)
• 1,300 V for a 500 V supply voltage, cable length depending on the dv/dt filter combination
• 1,600 V for a 690 V supply voltage, cable length depending on the dv/dt filter combination

The performance of dv/dt filters will be affected if the maximum cable lengths are exceeded. For an application with several motors connected in parallel, the cable length must include all cabling. If a cable longer than that specified is used, the dv/dt filters may overheat.

The switching frequency must be less than 8 kHz.