Using Power Factor Compensation Capacitors With The Drive; Using A Safety Switch Between The Drive And The Motor; Implementing The Control Of A Contactor Between Drive And Motor; Protecting The Contacts Of Relay Outputs - ABB ACS880-07LC drives Hardware Manual

Using power factor compensation capacitors with the drive

Power factor compensation is not needed with AC drives. However, if a drive is to be
connected in a system with compensation capacitors installed, note the following restrictions.
WARNING!
Do not connect power factor compensation capacitors or harmonic filters to the
motor cables (between the drive and the motor). They are not meant to be used
with AC drives and can cause permanent damage to the drive or themselves.
If there are power factor compensation capacitors in parallel with the input of the drive:
1. Do not connect a high-power capacitor to the power line while the drive is connected.
The connection will cause voltage transients that may trip or even damage the drive.
2. If capacitor load is increased/decreased step by step when the AC drive is connected
to the power line, make sure that the connection steps are low enough not to cause
voltage transients that would trip the drive.
3. Make sure that the power factor compensation unit is suitable for use in systems with
AC drives, ie, harmonic generating loads. In such systems, the compensation unit should
typically be equipped with a blocking reactor or harmonic filter.

Using a safety switch between the drive and the motor

ABB recommends to install a safety switch between the permanent magnet motor and the
drive output. The switch is needed to isolate the motor from the drive during maintenance
work on the drive.
Implementing the control of a contactor between drive and
motor
Implementing the control of the output contactor depends on the motor control mode and
stopping method selected.
When you select the DTC motor control mode and the motor ramp stop mode, use this
operation sequence to open the contactor:
1. Give a stop command to the drive.
2. Wait until the drive decelerates the motor to zero speed.
3. Open the contactor.
WARNING!
If DTC motor control mode is in use, do not open the output contactor while the
drive controls the motor. The motor control operates faster than the contactor, and
tries to maintain the load current. This can cause damage to the contactor.
When you select the DTC motor control mode and the motor coast stop mode, you can
open the contactor immediately after the drive has received the stop command. This is the
case also if you use the scalar motor control mode.

Protecting the contacts of relay outputs

Inductive loads (relays, contactors, motors) cause voltage transients when switched off.
Guidelines for planning the electrical installation 79