Bypass Contactor - Danfoss VLT MCD 500 Pocket Manual

Bypass Contactors:
When should a bypass contactor be used?
Bypass contactors bridge out the SCRs when the motor is running
at full speed, eliminating heat dissipation during run. This allows
the soft starter to be installed in enclosures without the need for
forced-air cabinet ventilation.
If a soft starter is installed in a totally sealed enclosure (>IP 54) it
must be bypassed.
Bypass contactors should be AC1 rated for the motor FLC (the
bypass contactor does not carry start current).
Soft starters may be internally or externally bypassed:
MCD 200 soft starters are internally bypassed,
with built-in bypass relays.
MCD 500 soft starters are internally bypassed up to 500 kW.
Non-bypassed models include relay outputs to control an
external bypass contactor. Dedicated bypass terminals
mean motor protection still operates even when the starter
is bypassed.
18 | Danfoss Drives · DKDD.PB.551.A1.02