Moeller 15-V-SWD, Hardware And Engineering

Page: 51 / 130

Engineering
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In an emergency, the power for the contactor coils can be
switched off using the enable circuit of the safety relay. By
the use of extra SmartWire-Darwin Power modules
protection groups are made that in an emergency can be
switched off together. With this circuitry, controls can be
assembled up to Safety Category 1 to EN 954-1.
Feedback circuit
The auxiliary contact integrated in the contactor is a mirror
contact according to IEC/EC 60947-4-1. Using this contact
the state of the main contacts can be reliably signalled. The
mirror contact can be included into the feedback circuit of
the safety relay so that the safety relay only gives a new
enable signal when the contactor is open.
Measures for higher safety categories
In many applications controllers of safety category 3 or 4 in
accordance with EN 954-1 are required. Controllers of
category 3 can be set up by means of an additional group
contactor which is connected in series upstream of the motor
junctions. In an emergency the control voltage for the motor
contactors and for the group contactor are switched off via
the safety relay. This redundant switching-off makes
category 3 controllers possible.