Vega VEGACAL 60 Series, Руководство по безопасности

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1 Functional safety
VEGACAL series 60 • Two-wire 4 … 20 mA/HART
35593-EN-181129
An associated characteristic is the value PFH (failure rate).
Number values see chapter "
Safety-related characteristics ".
The following assumptions form the basis for the implementation of
FMEDA:
•
Failure rates are constant, wear of the mechanical parts is not
taken into account
•
Failure rates of external power supplies are not taken into account
•
Multiple errors are not taken into account
•
The average ambient temperature during the operating time is
40 °C (104 °F)
•
The environmental conditions correspond to an average industrial
environment
•
The lifetime of the components is around 8 to 12 years
(IEC 61508-2, 7.4.7.4, remark 3)
•
The repair time (exchange of the measuring system) after an non-
dangerous malfunction is eight hours (MTTR = 8 h)
•
The processing unit can interpret " fail low " and " fail high " failures
as a disruption and trigger a suitable error message
•
The scanning interval of a connected control and processing unit
is max. 1 hour, in order to react to dangerous, detectable errors
•
Existing communication interfaces (e. g. HART, I²C-Bus) are not
used for transmission of safety-relevant information
The measuring system should be used appropriately taking pressure,
temperature, density, dielectric value and chemical properties of the
medium into account.
The user-specific limits must be complied with. The specifications of
the operating instructions manual must not be exceeded.
Keep in mind when using as dry run protection:
•
Avoid rod or cable breakage (probably smaller proof test intervals
will be necessary)
1.3 Instrument parameter adjustment
Since plant conditions influence the functional safety of the measur-
ing system, the instrument parameters must be set in compliance with
the application.
The following tools are allowed:
•
The DTM suitable for VEGACAL in conjunction with an adjustment
software according to the FDT/DTM standard, e. g. PACTware
•
Display and adjustment module
Note:
Make sure that DTM Collection 10/2005 or a newer version is used.
If the measuring system has not been ordered especially for applica-
tions in safety-instrumented systems (SIS), the parameter " Sensor
according to SIL " must be selected in the adjustment sofware in the
menu level " Basic setting ". If the display and adjustment module
Assumptions
General instructions and
restrictions
Adjustment tools
Create a measurement
loop