Safety Parameters - Beckhoff TwinSAFE EL2912 Operating Instructions Manual

Derating table for altitudes above 2000 m
The derating table (table 8) from the IEC 61131-2:2017 standard can be referred to for the use of the
TwinSAFE components above the specified maximum altitude.
Altitude in m
2
0 to 2000
3000
4000
5000
Note: Linear interpolation is permissible between the altitudes
1)
Ambient temperature of the device at an altitude of 2000 m
2)
The air pressure and air density increase as the altitude decreases. Therefore the derating factor for 0 to
2000 m (1.0) is used for altitudes below sea level.
Calculation example
In the following example the calculation is performed for a TwinSAFE component at an operating altitude of
4000 m.
Permissible ambient temperature up to 2000 m above sea level = 55 °C
Permissible ambient temperature up to 4000 m above sea level = 55 °C * 0.8 = 44 °C
Compliance with the temperature limits
The TwinSAFE component has a maximum internal temperature at which a switch-off takes place. This is
designed for the maximum permissible ambient temperature. If the derating factor for the temperature for
higher altitudes is used, the user is solely responsible for ensuring that the calculated maximum ambient
temperature is complied with.
3.4

Safety parameters

Characteristic numbers
Lifetime [a]
Prooftest Interval [a]
PFH
D
PFD
MTTF
D
DC
Performance level
Category
HFT
2
Element classification
1)
No special proof tests are required during the entire service life of the EL2912.
2)
Classification according to IEC 61508-2:2010 (chapter 7.4.4.1.2 and 7.4.4.1.3)
The EL2912 EtherCAT Terminal can be used for safety-related applications within the meaning of
EN 61508:2010 up to SIL3 and EN ISO 13849-1:2015 up to PL e (Cat 4).
Further information on calculating or estimating the MTTF
TwinSAFE Application Guide or in EN ISO 13849-1:2015, Table K.1.
In terms of safety-related parameters, the Safety-over-EtherCAT communication is already considered with
1% of SIL3 according to the protocol specification.
EL2912
Derating factor for the temperature
1.0
0.9
0.8
0.7
CAUTION
EL2912
20
1
not required
2.88 E-09
2.55 E-05
high
high
PL e
4
1
Type B
value from the PFH
D
Version: 1.0.0
Product description
1
value can be found in the
D
17