schmersal PSC1 Series Installation Manual page 49

Installation manual
4.2.1.4.3 Dual-channel sensor without time monitoring with cross-circuit testing
Faults are detected as a minimum on demand. The DC is medium and can be changed to the
high category by using cyclic tests (start tests, operative/organisational tests) depending on
the test frequency.
For this purpose only normally closed contacts are to be used for safety applications.
PL d according to EN 13849-1 can be achieved on the usage of sensors / switching elements
with fault exclusion for the failure of the switching contacts to open. This exclusion is allowed
on the usage of positively opening switches with correct positive actuation. It is also allowed to
use sensors with self-monitoring output contacts.
PL e according to EN 13849-1 can be achieved on the usage of diverse sensors / input
elements with an adequately high MTTFd in conjunction with plausibility monitoring of the
timing and an adequately high change in switching state = dynamic testing.
X14
I01
I02
I03
I04
.
.
.
I13
I14
T1
T2
X12
L+
L-
Figure: Homogeneous dual-channel sensor without test pulses, with positive opening
X14
I01
I02
I03
I04
.
.
.
I13
I14
T1
T2
X12
L+
L-
Figure: Diverse dual-channel input element, without test pulses
HB-37350-810-01-38F-DE PSC1-C-10 Installation manual V1.1.docx
Version: 38F
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