Product description
EP1918
13
Version: 1.1.0
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
Derating factor for the temperature
1
0 to 2000
2
1.0
3000
0.9
4000
0.8
5000
0.7
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
CAUTION
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
EP1918-0002
Lifetime [a]
20
Proof test interval [a]
not required
1
PFH
D
5.00E-09
PFD
6.90E-05
MTTF
D
high (875 a)
DC
high (98,6% CAT 4)
Performance level
PL e
Category
4
HFT
1
Element classification
2
Type B
1)
Special proof tests throughout the service life of the EtherCAT Box are not required.
2)
Classification according to EN 61508-2:2010 (see chapter 7.4.4.1.2 and 7.4.4.1.3)
The EP1918-0002 TwinSAFE EtherCAT Box can be used for fail-safe applications within the meaning of
IEC 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
D
value from the PFH
D
value can be found in the
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.
Summary of Contents for EP1918
Page 2: ......
Page 30: ...Operation EP1918 30 Version 1 1 0 Fig 19 Creating alias devices by the user ...
Page 53: ...Appendix EP1918 53 Version 1 1 0 5 3 Certificates ...
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