Safety considerations
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06/10 MN03402004Z-DE/EN
Safety considerations
Motor-protective circuit-breaker PKE have been examined by
TSC (Transport Safety Consult of TÜV Rheinland InterTraffic
GmbH) for suitability for safety integrity level (SIL) 2; report
no. 401/13101704/002.
The examination consisted of the following steps:
• Risk analysis of hazards, hazardous situations and
hazardous events to EN ISO 14121,
• Determination of SIL using the risk graph according to
IEC 61508,
• Determination of hazardous failure rate,
• Verification of implementation of the measures against
systematic faults to IEC 61511.
Basic information
In terms of its architecture, motor-protective circuit-breaker
PKE (basic device and trip block) consists of a single channel.
With this architecture, every hazardous failure causes failure
of the safety function in the event of a demand. Motor-
protective circuit-breaker PKE is therefore a 1001 system
with a high demand rate (>1/year).
According to EN ISO 13849 a category must be specified for
motor-protective circuit-breaker. Motor-protective circuit-
breaker PKE meets the requirements for Category 2 for the
following reasons:
• The occurrence of a fault can lead to the loss of the safety
function between the checks.
• The loss of safety function is detected by the check.
A risk analysis using the risk graph from IEC 61508-5 has
verified that, for typical usage scenarios in the chemical
industry, a safety integrity level of SIL1 or 2 according
IEC 62061 can be expected. The required Performance Level
(PL
r
) to EN ISO 13049-1 has a value of “d” or “e”.
Summary of Contents for PKE12 Series
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