Endress+Hauser Deltapilot S FMB70 - Safety-Related Failures According to IEC; en 61508; Safety Measured Error

Design Deltapilot S FMB70
10 Endress+Hauser
3.4.1 Safety-related failures according to IEC / EN 61508
Safety-related error Explanation Implications for the
safety related output
signal
Implications for measuring uncertainty (see item number in
graphic below)
No device error Safe: SD
No error
None 1 Is within the specification (see TI, BA, ...)
λ
S
Safe failure Causes the output signal to
signal the failsafe mode
3 No implications
λ
S
Safe failure Is within the defined error
range
2 May be outside specifications
λ
DD
Dangerous detected:
Dangerous failure which
can be detected
(diagnostic at the device)
Causes the output signal to
signal the failsafe mode
3 No implications
λ
DU
Dangerous undetected:
Dangerous failure which
cannot be detected
May be outside the
defined error range
4 May be outside the defined error range
I [mA]
B
C
A
t
1
2
4
3
3
A0025264
A Hi-Alarm ≥ 21 mA
B Error range ± 1 %
C Lo-Alarm ≤ 3.6 mA
3.4.2 Safety measured error
The total deviations with regard to the safety-related current output are composed of:
• Measured errors under reference operating conditions: as per Technical Information
• Measured errors due to process/installation/ambient conditions: as per Technical
Information
• Measured errors due to ambient conditions (EMC): ±0.5 % based on the span of the
safety-related current output
Strong, pulse-like EMC interference on the power supply line can result in transient
(< 1 s) deviations in the output signal (≥ ±1 % based on the span of the safety related
current output). Therefore, filtering with a time constant ≥ 1 s should be performed in
the downstream logic unit.
• Measured errors due to random component failures (SIL error range): ±1 % based on the
span of the safety-related current output