| Technical
Information
The JSBR4 has two inputs, which both
have to be closed to keep the safety output contacts
closed. A short circuit across the inputs will cause
the output contacts to open. The inputs can however
be subjected to a continuous short circuit without damaging
the safety relay.
In order to make the safety outputs
close the reset input must be closed and opened. In
this way an unintentional reset is prevented in the
case of a short circuit in the reset button cable or
if the button gets jammed in the actuated position.
The reset input can also be used for test/supervision
to ensure that contactors or valves have returned to
their initial off "stop" position before a
new start can be allowed by the safety relay.
When the JSBR4 is used as a Two Hand
relay both buttons have to be pressed within 0.5 seconds
of each other in order to close the outputs.
When the JSBR4 is used for Safety Mats
and Safety Strips the 'stop' condition is given following
detection of a short circuit between input channels
A and B. Neither the safety mat, safety strip or the
relay will be damaged by a continuous short circuit.
This also gives the advantage that if there is a failure
between the inputs in the installation, the safety relay
will not be damaged.
Regulations
and Standards
The RT7 is designed and approved in
accordance with appropriate standards. Examples of such
are: EN 292-1/2, EN 60204-1, EN 954-1.The JSBR4 complies
with the highest safety level for connection of a two-handed
control device of type IIIc in accordance with EN574.
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