Handheld Terminal Connection
User's Manual, Version: 1.3 27
© KEBA 2007
The safety category 3 means, that one failure must not lead to the loss of
the safety function, and whenever possible, the single failure is detected.
The chapters „
Example of Connection with PILZ PST1 Control Relay“ and
“Example of Connection with ELAN SRB-NA-R-C.27/S1 Control Relay”
show how the safety
category 3 can be fulfilled with the KeTop and its
safety-related parts. The entire concept of the machine must be laid out ac-
cording to the principles of safety category 3.
The monitoring of the simultaneity by the control relay is necessary, be-
cause otherwise maybe a failure culmination would not be recognised and
this would cause the loss of safeness:
Example:
If one circuit of the enabling device switches to the enabled state
as a result of a failure and after some time the second circuit also switches
to the enabled state as a result of an failure, then no de-energisation by the
enabling device would be possible.
Further the EN 60204-1:1997 prescribes that the enabling switches shall be
connected to a category 0 stop or a category 1 stop, that means the energy
must be switched off.
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