Application manual for YRB-4EML-31S safety relay
Contrinex AG Industrial Electronics
18
(
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3 Safety technology basics
3.1
Cross-circuit detection
In both category 3 and category 4, a first fault must never lead to the loss of the safety
function. This often makes it necessary to provide redundancy in the control structure.
Cross-circuit detection has the ability to detect short circuits, bridges or short circuits to
ground between two channels either immediately or within the framework of cyclic self-
monitoring.
A cross circuit may be due to one of the following reasons:
– Squeezing
– High temperatures
– Chips
– Acids
L+
(L1)
1.
2.
A1
S11 S12
S21 S22
(+)
( )
(GND) ( )
PTC
3.
K1
K2
( )
A2
S33 S34
M
(N)
Figure 6
Cross-circuit detection
