Implementing The Control Of A Contactor Between Drive And Motor; Implementing A Bypass Connection; Protecting The Contacts Of Relay Outputs - ABB ACS880 Manual

46 Electrical planning guidelines
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.

Implementing a bypass connection

If bypassing is required, employ mechanically or electrically interlocked contactors
between the motor and the drive and between the motor and the power line. Make
sure with interlocking that the contactors cannot be closed simultaneously. The
installation must be clearly marked as defined in IEC/EN/UL 61800-5-1, subclause
6.5.3, for example, "THIS MACHINE STARTS AUTOMATICALLY".
Bypass connection is available as a factory-installed option for some cabinet-installed
drive types. Consult ABB for more information.
WARNING!
Never connect the drive output to the electrical power network. The connection
may damage the drive.

Protecting the contacts of relay outputs

Inductive loads (relays, contactors, motors) cause voltage transients when switched
off.
Install the protective component as close to the inductive load as possible. Do not
install protective components at the relay outputs.