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PRE-STARTUP ACCEPTANCE TEST
After the installation of the device in order to validate the
required safety functionality of the system together with the
target equipment according to the Safety Requirement
Specification a Pre-Startup Acceptance test shall be performed
as following:
1. Put the Write Protect Mode switch in operating position
2. Power-on the transmitter: the transmitter performs
automatically a self-test that consists in the operations
below:
- Switch-on of the Secondary output
- RAM test
- Test of the analog output stage and of the feedback A/D
converter
In case the first condition wouldn't happen, the transmitter shall
be considered failed and not possible to use. In case the
second test would fail the transmitter will drive the output to the
selected alarm status. In this case a correction action consists
in the re-calibration of the A/D converter. After the correction
action the pre-startup test shall be repeated.
3. Enable the transmitter maintenance mode by raising up to
dip switch nr. 4 (write enable)
4. Perform the Hart Command "Change Transmitter status to
Maintenance"
5. Perform the Hart Command "Clock monitor test". The
transmitter simulates a clock failure and put the output to
Up-scale by the supplementary output stage. In case this
condition wouldn't happen, the transmitter shall be
considered failed and not possible to use
6. Disable the transmitter maintenance mode by lowering the
dip switch nr. 4 (write protect)
7. Put the Operating/maintenance switch in operating condition
8. Power-on the transmitter.
A pre-startup acceptance test report shall be produced to
record the test results.
PROOF TESTS
To maintain the claimed Safety Integrity Level (SIL 2) a
proof test procedure is requested every 10 years. The
proof tests consists in the following operations:
1. Put the Write Protect Mode switch in Write Enable condition.
2. Perform the Hart Command "Change Transmitter status to
Maintenance"
3. Perform the Hart Command "Clock monitor test". The
transmitter must go to up-scale setting the secondary
output stage. To recover from the alarm status a power-off,
power-on operation is required.
4. Power-off the transmitter
5. Put the Write Protect Mode switch in Write Disable condition.
6. Power-on the transmitter. The transmitter must go first to
up-scale setting the secondary output stage, then finally the
output must provide the actual pressure value.
Location of the links on the electronics
SAFETY RELATED PARAMETERS
The Safety 2600T pressure transmitters product meets the SIL2 requirements of IEC 61508 in low as well as high demand mode
of operation. The total PFD in low demand mode for 10 years proof test interval is equal to the 5.5% of the range defined in
IEC 61508-1. The relevant numbers are stated in the below tables.
Safety related parameters (electronics)
Safe Detected Failure Rate (Lambda SD) 103 FIT
Safe Undetected Failure Rate (Lambda SU) 235 FIT
Dangerous Detected Failure Rate (Lambda DD) 490 FIT
Dangerous Undetected Failure Rate (Lambda DU) 11 FIT
Diagnostic Coverage (DC) 97.75 percent
Safe Failure Fraction (SFF) 98.66 percent
T1 (proof test interval) 1 year 10 years
MMTR (Mean Time to Repair) 8h 8h
PFD (avg) 5.3E-05 5E-04
Safety related parameters (electronics and mechanics)
Safe Detected Failure Rate (Lambda SD) 112 FIT
Safe Undetected Failure Rate (Lambda SU) 275 FIT
Dangerous Detected Failure Rate (Lambda DD) 549 FIT
Dangerous Undetected Failure Rate (Lambda DU) 61 FIT
Diagnostic Coverage (DC) 89.96 percent
Safe Failure Fraction (SFF) 93.86 percent
T1 (proof test interval) 1 year 10 years
MMTR (Mean Time to Repair) 8h 8h
PFD (avg) 2.7E-04 2.7E-03
Upscale/Downscale
link
Write Protect
Mode link
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