Endress+Hauser Proservo NMS80 Functional Safety Manual

Proservo NMS80/81/83
10 Endress+Hauser
Restrictions for use in safety-
related applications
• The measuring system must be used correctly for the specific application, taken into account the
medium properties and ambient conditions. Carefully follow instructions pertaining to critical
process situations and installation conditions from the Operating Instructions. The application-
specific limits must be observed.
• Information on the safety-related signal, (→  9).
• The specifications from the Operating Instructions must not be exceeded, (→  7).
• The following restrictions also applies to safety-related use:
– Strong, pulse-like EMC interference on the line can cause transient (< 1 s) deviations ≥ ±2% in
the output signal. For this reason, filtering with a time constant of ≥ 1 s should be performed in
the downstream logic unit.
– The error range is device specific and is defined according to FMEDA (Failure Modes, Effects and
Diagnostic Analysis) on delivery. It includes all influential factors described in the Technical
Information (e.g. non-linearity, non-repeatability, hysteresis, zero drift, temperature drift, EMC
influences).
According to IEC / EN 61508 the safety related failures are classified into different categories,
see the following table. The table shows the implications for the safety-related analog output
signal and for measuring uncertainty.
Safety related error Explanation Implications for the
safety related output
signal
Implications for the
measuring uncertainty
(Position, see figure.
→  10)
No device error Safe:
No error
None 1 Is within the
specification (see TI,
BA, ...)
λ
SD
Safe detected:
Safe failure which can be
detected
Causes the output signal
to signal the failsafe mode
(see, →  12)
3 No implications
λ
SU
Safe undetected:
Safe failure which cannot
be detected
Is within the defined error
range
2 May be beyond the
specification
λ
DD
Dangerous detected:
Dangerous failure which
can be detected
(Diagnostic within the
device)
Causes the output signal
to signal the failsafe mode
(see, →  12)
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 ±2 %
C LO-Alarm ≤3.6 mA

Endress+Hauser Proservo NMS80 Specifications

General

Brand	Endress+Hauser
Model	Proservo NMS80
Category	Measuring Instruments
Language	English