Feedback Circuit; Measures For Higher Safety Categories - Eaton Moeller SmartWire-Darwin Series Hardware And Engineering

06/09 AWB2723-1613en
Engineering
In an emergency, the control voltage for the contactor coils
can be switched off using the enable paths of the safety
relay. Additional SmartWire-Darwin power modules can be
used to form contactor groups that are switched off in the
event of an emergency. This type of circuit allows the setting
up of control systems up to Safety Category 1 in accordance
with EN 954-1. The safety relay must comply with category
1 or higher (e.g. ESR4-NO-31) in this example.

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, safety category 3 or 4 control systems
are required in accordance with EN 954-1. Controllers of
category 3 can be set up by means of an additional group
contactor which is connected in series upstream of the motor
feeders. The control voltage for the motor contactors as well
as for the group contactor is switched off in an emergency
via the safety relay. This redundant disconnection circuit
enables the implementation of Category 3 control systems.
The safety relay used must comply with Category 3 or higher
(e.g. ESR4-NOE-31) to attain this safety category.
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