Specifications

PHOENIX CONTACT 39
04.04.2008 12:56:20 Uhr04.04.2008 12:56:20 Uhr
del
s for a particular machine
operated. Based on
rer
uses the CE marking to declare that all the relevant
Union
en adhered
Area of application of the new safety standards
So far, the EN 954-1 had to be used as a proof for the
fulfillment of the essential health and safety requirements
specified in the machinery directive. Since today not only
electronics, but in particular programmable electronics have
established themselves in safety engineering, safety can no
longer be measured using the simple category system of
EN 954-1.
Due to the deterministic concept of the standard in which all
variables are clearly laid down, no more statements about the
probability of a failure can be made. As the successor
standards of EN 954-1, the new EN ISO 13849-1 and the
harmonized EN IEC 62061 standards provide a probalistic
approach that works with statistical probabilities.
Why does a supposedly identical field of application have two different standards?
EN ISO 13849-1 EN IEC 62061
Comes from EN 954-1:1996 and is supplemented
with quality management and reliability aspects
Best suited for less complex systems
Can also be used for other technologies apart from
electronics, e.g. pneumatic or hydraulic system
Suitable for proof of safety of devices as well as for
evaluation of risk reduction of the entire safety function
via tables
Sector standard for the field of machines that was
created on the basis of IEC 61508
Can only be used for highly complex electronic
technology and here particularly for complex
programmable systems
Procedure for proof of safety of electronic technology
based on IEC 61508
Suitable for proof of safety of devices as well as for
evaluation of risk reduction of the entire safety function
through calculation
From categories to probabilities
Performance Level
(PL)
EN ISO 13849-1
One risk failure every
10000 hours
SIL as per
IEC 61508 and
EN IEC 62061
Max. acceptable safety
system failure
a
b
e
c
d
≥ 10
-5
to < 10
-4
≥ 3x10
-6
to < 10
-5
≥ 10
-6
to < 3x10
-6
≥ 10
-7
to < 10
-6
≥ 10
-8
to < 10
-7
–
1
1
2
3
One risk failure every
1250 days
One risk failure every
115.74 years
One risk failure every
115.74 years
One risk failure every
1,157.41 years
Unlike the deterministic concept of
EN 954-1, the EN ISO 13849-1 and
the EN IEC 62061 are based on a
probabilistic concept that takes into
account the probability of those
errors occurring that lead to a safety
function failure and categorizes them
as PL or SIL (high demand).
Mean probability of one
dangerous failure per hour