Proline Promass 500
Safety function
Hauser
15
5
Safety function
5.1
Definition of the safety function
The measuring device's permitted safety functions are:
• Monitoring of a maximum or minimum mass flow or a mass flow range for liquid or
gaseous media
• Monitoring of a maximum or minimum volume flow or a volume flow range for liquid
media
The safety functions are based on the simultaneous, continuous measurement of the mass
flow and the density of a liquid.
• Monitoring of a maximum or minimum density or a density range for liquid media
5.1.1
Safety-related output signal
The measuring device's safety-related signal is the 4–20 mA analog output signal (output;
input 1). All safety measures refer to this signal exclusively.
In devices with several outputs, only current output 1 (terminals 26 and 27) is suitable for
safety functions. The other outputs can, if necessary, be connected for non-safety-oriented
purposes.
The safety-related output signal is fed to a downstream automation system where it is
monitored for the following:
• Overshooting and/or undershooting of a specified limit value for the flow or the density of
the medium
• The occurrence of a fault: e.g. failure current (≤ 3.6 mA, ≥ 21 mA), interruption or short-
circuit of the signal line
The safety-related errors are broken down in accordance with IEC/EN 61508 into different
categories and implications for the safety-related output signal.
Safety related
error
Explanation
Implication for safety-related output
signal
No device error Safe:
No error
1
Within specification
λ
SD
Safe detected:
Safe, detectable failure present
3
Device assumes a signal on alarm
λ
SU
Safe undetected:
Safe, undetectable failure present
2
Is within the specified tolerance range
λ
DD
Dangerous detected:
Dangerous but detectable failure
present (diagnosis in device)
3
Device assumes a signal on alarm
λ
DU
Dangerous undetected:
Dangerous, undetectable failure
present
4
May be outside the specified tolerance
range
Summary of Contents for HART Proline Promass 500
Page 2: ......
Page 8: ...Certificate Proline Promass 500 8 Endress Hauser 2 Certificate A0033748 ...
Page 50: ......
Page 51: ......
Page 52: ...www addresses endress com ...