Protective Instrument Loop Final Element Group Records

Protective Instrument Loop Final Element Group records store details about a protective instrument loop final element group that you have created as part of SIL verification. This topic provides an alphabetical list and description of the fields that exist for the Protective Instrument Loop Final Element Group family and appear on the Protective Instrument Loop Final Element Group datasheet by default. The information in this table reflects the baseline state and behavior of these fields.

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Field	Data Type	Description	Behavior and Usage
ATI / PVST Automatic/Manual	Character	Indicates whether partial valve stroke testing (PVST) is automatic or manual.	You can select one of the following values: Automatic Manual
ATI / PVST Coverage	Number	The percentage of failures expected detected by PVST.	None
ATI / PVST Enabled	Logical	Indicates if PVST is performed on the final elements in the group.	If this field is selected, then the following fields are enabled: ATI / PVST Automatic/Manual ATI / PVST Interval ATI / PVST Interval UOM
ATI / PVST Interval	Number	The interval at which the PVST is performed on the final elements in the group.	It is recommended that the partial valve stroke test interval is performed at least an order of magnitude more frequent than the proof test. For example, if you perform the proof test once a year, you must perform the PVST at least once a month.
ATI / PVST Interval UOM	Character	The units of the PVST interval that you have specified in the ATI / PVST Interval field.	You can select one of the following values: Months Days
Availability	Number	A number representing the percentage of time that the final element in the group are expected to be available in the case of a demand.	The GE Digital APM system calculates this value automatically as follows: *Availability = (1-PFD Avg.) 100**
Calculated PFD Avg	Number	A number representing the probability that the final element group will fail to react during a demand when the loop is operating in a low demand mode.	This field is disabled. The GE Digital APM system calculates and populates this value. This value depends on the failure rate of the final element group.
Calculated PFH	Number	A number representing the probability that the final element group will fail to react during a demand when the loop is operating in high demand or continuous mode of operation.	This field is disabled. The GE Digital APM system calculates and populates this value. This value depends on the failure rate of the final element group.
Calculated STR	Number	A number representing the spurious trip rate for the final element group.	This field is disabled. The GE Digital APM system calculates and populates this value.
Common Cause (Beta)	Number	A number representing the percentage of failure that would affect the functioning of multiple devices. For example, a power supply failure for a final element group that is shared across multiple loops can cause all the loops to fail. In this case, the beta factor is the probability that the loops fail in case of a power supply failure to the final element group.	If the value in the Voting field is 1oo1, this value is not applicable. This value is populated automatically when you select a device. If the Final Element Group contains multiple Final Elements, then you can enter a value manually in this field.
Custom Vote M	Number	The minimum number of final elements that should trip when the final element detects a potential hazard.	You must use this option if you want to add more than six final elements in the group. If the number of final elements in the group is less than or equal to six, then this field is disabled and populated with the minimum number of final elements that should trip in the event of a potential hazard (the first digit in the Voting field).
Custom Vote N	Number	The number of final elements in the group.	You must use this option if you want to add more than six final elements in the group. If the number of final elements in the group is less than or equal to six, then this field is disabled and populated with the number of final elements (the last digit in the Voting field).
Diverse	Logical	Indicates whether the final elements in the group are similar or diverse.	If you clear this check box, all the final elements in the group are similar. Hence, all the final elements in the group will have datasheets with the same values, except for the Final Element ID. If you modify the details of a final element, the same change is reflected in all the final element datasheets. By default, the check box is cleared. If you select this check box, each final element in the group will have a datasheet with different values. If there are more than three final elements in the group, this field is cleared. If there is only one final element in the group, this field is disabled.
Group ID	Character	The ID of the protective instrument loop.	This value is required and must be unique. The GE Digital APM system provides a default value, which you can modify if required.
MTTFS	Number	Mean Time To Fail Spuriously. It is the average amount of time between failures of final elements in the group that occur during safe scenarios.	This field appears in the Calculated Results section and is disabled. This value is measured in years.
MTTR	Number	Mean Time To Repair. It is the average time that is required to repair the final elements in the group.	This value is measured in hours and is required.
Proof Test Coverage	Number	The percentage of failures that are detected by the proof test (i.e., how effectively the proof test identifies failures). For example, 100% proof test coverage indicates that the proof test would identify 100% of the failures that occurred.	By default, this value is required and is set to 0.
Proof Test Interval	Number	A numeric value representing the frequency at which the proof test should be performed.	This value is set to 12 by default. You can, however, change this value if required. This value is required and is measured in months.
SIL Architectural Constraints	Number	A number that represents the SIL value for the final element group, which is based on the architectural constraints that are defined in the Test Architecture Constraints field.	This field is disabled. The GE Digital APM system calculates and populates this value.
SIL Systematic Capability	Number	A number that represents the SIL value for the final element group, which is based on the systematic capability that is defined in the Test Architecture Constraints field.	This field is disabled. The GE Digital APM system calculates and populates this value.
Use Custom PVST Coverage	Logical	Indicates whether custom PVST coverage is considered.	None
Voting	Character	The voting architecture that represents the minimum number of final elements that should trip (in the event of a failure) and the number of final elements available in the group. For example, if the voting is 1oo2, then for the logic solver to detect a failure, at least one final element should trip out of the two final elements that are available in the group.	This field is updated automatically when you add or remove a final element from the group. The following combinations are available: 1oo1 1oo2 2oo2 1oo3 2oo3 3oo3 1oo4 2oo4 [2oo(1oo2)] 4oo4 5oo5 6oo6 MooN This value is required. These values are defined in the MI_SIL_FINALELEMVOTE system code table.