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.
The relay contacts on the drive control unit are protected with varistors (250 V) against
overvoltage peaks. In spite of this, it is highly recommended that inductive loads are
equipped with noise attenuating circuits (varistors, RC filters [AC] or diodes [DC]) to
minimize the EMC emission at switch-off. If not suppressed, the disturbances may
connect capacitively or inductively to other conductors in the control cable and form
a risk of malfunction in other parts of the system.
Install the protective component as close to the inductive load as possible. Do not
install protective components at the relay outputs.
112 Guidelines for planning the electrical installation
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