Cmd Contactor Monitoring Device; Application Of The Cmd - Eaton CMD Handbuch

1 CMD contactor monitoring device

1.1 Application of the CMD

1 CMD contactor monitoring device
1.1 Application of the CMD
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In the event of an emergency in safety-related electrical control circuits, the
hazardous plant section is shut down from the main power supply by means
of contactors a Emergency stop (stopping in the event of an emergency) in
accordance with IEC/EN 60204-1.
For Category 3 control systems in compliance with EN/ISO 13849, the
connection of two contactors in series is recommended. This technique can
be replaced using one contactor and the CMD contactor monitoring device
connected to the backup circuit-breaker/motor-protective circuit-breaker in
the plant.
The contactors must be provided with an auxiliary NC contact that operates
as a mirror contact in accordance with IEC/EN 60947-4-1 Annex F.
The contactors also require an additional auxiliary NO contact. The motor-
protective circuit-breakers/circuit-breakers are provided with an undervoltage
release.
In the event of a hazard the contactor is disconnected via an upstream safety
PLC or a safety relay by means of an enable contact. The CMD compares the
control voltage of the contactor with the status of the main contacts. The
status of the main contacts is monitored via an auxiliary NC contact that acts
as a mirror contact in accordance with IEC/EN 60947-4-1 Annex F.
If the contactor is welded, the status of the main contacts does not
correspond to the status of the control voltage. The undervoltage release of
the backup circuit-breaker is tripped via an internal relay in the CMD.
This disconnects the outgoing section. The undervoltage release prevents
the welded contactor from be switched on again.
The CMD contactor monitoring device is approved by the IFA in combination
with Eaton contactors and circuit-breakers (￫ section 1.2, "System
overview", page 25).
A CE declaration of conformity and a prototype test certification are also
available.
CMD(220-240VAC), CMDB 01/20 MN121002ZU-DE/EN www.eaton.com