NORSTAT Safety Relays - Handbuch (Seite 14)

application guide safety relays from riese electronic page 14
a
b
c
d
e
starting point
high safety
P2
P1
P2
P1
P2
P1
P2
P1
F1
F2
F1
F2
S1
S2
low safety
S - severity of injury
S1 - slight injury
(usually reversible)
S2 - serious injury, including death
(usually irreversible)
F - frequency and duration of exposure to the hazard
F1 - rarely to many a time residence
F2 - more likely to permanent residence
P - the probability of avoidance of a hazardous event
P1 - possible under certain conditions
P2 - hardly possible
EN 62061 (Safety of machines - func tional safety of safety-related electrical, electronic and
programmable electronic control systems)
With the risk graph it is possible to investigate all safety-relevant functions and areas of a machine
respectively. The results are the so-called Safety Integrity Level / SIL (1 - 3).The SIL is required
for
the selection of the safety setup and the corresponding components including wiring. The 1 stands
for low safety and the 3 for high safety.
Class K (=F+P+A) Effect
and severity S
Frequency and
duration F
Probability
P
Avoidance
A 3-4 5-7 8-10 11-13 14-15
Death, losing an
eye or arm 4 ≤ 1 h 5 very high 5
SIL2 SIL2 SIL2 SIL3 SIL3
Permanent, losing
a finger 3 > 1 h - ≤ 1day 5 likely 4
OM SIL1 SIL2 SIL3
Reversible,
requiring attention
from a medical
practioner 2 > 1 day - ≤ 2
weeks
4 possible 3 impossible 5
OM SIL1 SIL2
Requiring first
help 1 > 2 weeks - ≤ 1
year
3 rarely 2 possible 3
OM SIL1
> 1 year 2 negligible 1 likely 1
OM = other measures advised
3. Safety design
The safety function described in step 1 is designed. The single components are defined, e.g. safety
relais SAFE CL for the ESPD-function.
4. Definition of the achived performance
The actual performance of the safety function is detected. The safety function is divided in sensors, logic
and actuators. The parameters required to calculation are provided by the component manufactures.
5. Verification
For each single safety function, the in step 4 achieved performance has to be bigger or equal as the in
step 2 defined required performance. If this is not the case the safety function has to be improved.
6. Validation
For the safety function, the validation ensures that all safety-relevant parts achieve the requirements.
required Performance Level (PL)
NORSTAT INC. 300 Roundhill Dr. Rockaway, NJ 07866 Tel: 973-586-2500 Fax: 973-586-1590 www.norstat.com