Protective Instrument Loop Records

Protective Instrument Loop records store details about a protective instrument loop 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 family and appear on the Protective Instrument Loop 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
Achieved SIL	Number	A number representing the overall SIL value for the protective instrument loop.	This list appears in the Calculated Results section and contains the following options: 0 (zero) 1 2 3 4 When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, this field is disabled and populated automatically with the lowest value of the values stored in the following fields: Calculated SIL Calculated SIL Architectural Constraints Calculated SIL Systematic Capabilities For example, if the value in each of these fields is 2, the value in the Achieved SIL field will be 2. If the value in two of the fields is 2 and the value in one of the fields is 1, the value in the Achieved SIL field will be 1.
Application Test Method	Character	The application test method that is used in the loop.	This list contains the following options: IEC 61508 IEC 61508 : 2010 tables [per 61511-1 11.4.5] IEC 61508 : 2000 tables [per 61511-1 11.4.5] IEC 61511 [ignore 11.4.3 for Type A devices] IEC 61511 IEC 61511 [ignore 11.4.3 for Type A devices] These values are defined in the MI_ARCHITECTURE_CONSTRAINT System Code Table.
Availability	Number	A number representing the percentage of time that the protective instrument loop is expected to be available in the case of a demand.	This field appears in the Calculated Results section and is enabled or disabled based on the following criteria: When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the GE Digital APM system calculates this value automatically as follows: *Availability = (1-PFD Avg.) 100**
Calculated SIL	Number	A number representing the SIL value for the protective instrument loop, which is the value stored in the Loop PFD Avg field.	This field appears in the Calculated Results section and is enabled or disabled based on the following criteria: When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the GE Digital APM system calculates this value automatically, based on the value in the Loop PFD Avg field, and displays one of the following values as read-only: 0 (zero) 1 2 3 4
Calculated SIL Architectural Constraints	Number	The SIL value for the protective instrument loop, which is based on architectural constraints defined in the Test Architecture Constraints field.	This field appears in the Calculated Results section on the datasheet and is enabled or disabled based upon the following criteria: When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the GE Digital APM system calculates this value automatically, based on the value in the Test Architecture Constraints field, and displays one of the following values as read-only: 0 (zero) 1 2 3 4
Calculated SIL Systematic Capabilities	Number	The SIL value for the protective instrument loop, which is based on systematic capabilities defined in the failure rate data associated with each protective instrument loop element. This is the lowest SIL value among the SIL values of all the elements in the loop. For example, assume that the elements in the loop are capable to achieve the following SIL values: Logic Solver - 3 Sensor - 2 Final Element - 1 Then the SIL value for the entire protective instrument loop is 1.	This field appears in the Calculated Results section and is enabled or disabled based on the following criteria: When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the GE Digital APM system calculates this value automatically, based on the systematic capabilities defined in the failure rate data associated with each protective instrument loop element, and displays one of the following values as read-only: 0 (zero) 1 2 3 4
Calculated STR	Number	A number representing the spurious trip rate for the protective instrument loop.	This field appears in the Calculated Results section and is enabled or disabled based on the following criteria: When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the GE Digital APM system calculates this value automatically and displays that value as read-only.
Demand Mode	Character	Represents the estimated probability that a dangerous condition will exist where the instrumented function is required to take the process to its safe state. For instance, if the demand rate is more than once a year, the hazard rate must not be higher than the failure rate. In this case, the SIL mode is high demand or continuous.	This field is disabled and populated automatically with the value stored in the SIL Mode field in the Instrumented Function that is linked to the Protective Instrument Loop.
Description	Character	A brief description of the protective instrument loop.	None
Final Element MCI	Number	A percentage that represents the Maintenance Capability Index.	This field contains the following options: MCI 0 (0%) : Indicates that repair actions are never performed. MCI 1 (60%) : Indicates that repair actions are effective 60 percent of the time. MCI 2 (90%) : Indicates that repair actions are effective 90 percent of the time. MCI 3 (99%) : Indicates that repair actions are effective 99 percent of the time. MCI 4 (100%) : Indicates that repair actions are always performed perfectly.
Last Modified By	Character	The name of the user who last modified the record.	This field is disabled and populated with the name of the GE Digital APM Security User who last modified the Protective Instrument Loop.
Last Modified Date	Date	The date on which the record was last modified.	This field is disabled and populated with the date on which the Protective Instrument Loop was last modified.
Logic Solver MCI	Number	A percentage that represents the Maintenance Capability Index.	This field contains the following options: MCI 0 (0%) : Indicates that repair actions are never performed. MCI 1 (60%) : Indicates that repair actions are effective 60 percent of the time. MCI 2 (90%) : Indicates that repair actions are effective 90 percent of the time. MCI 3 (99%) : Indicates that repair actions are effective 99 percent of the time. MCI 4 (100%) : Indicates that repair actions are always performed perfectly.
Loop Class	Character	A value that indicates whether the protective instrument loop is designed to mitigate safety risks or commercial risks.	This list contains the following options: Safety : Indicates that the protective instrument loop is designed to mitigate risks related to safety. For example, a safety loop might prevent a high motor current from causing a fire. Protective : Indicates that the protective instrument loop is designed to mitigate commercial risks only. For example, a protective loop might prevent low lube pressure from causing a mechanical failure where there is no safety risk involved.
Loop ID	Character	The ID of the protective instrument loop.	This value is required and must be unique.
Loop PFD Avg	Number	A number representing the probability that the protective instrument loop will fail in the event of a demand while operating in low demand mode.	This field appears in the Calculated Results section, which is enabled or disabled based on the following criteria: When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the GE Digital APM system calculates this value automatically and displays that value as read-only.
Loop PFH	Number	A number representing the probability per hour that the protective instrument loop will fail in the event of a demand while operating in high demand or continuous mode.	This field appears in the Calculated Results section, which is enabled or disabled based on the following criteria: When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the GE Digital APM system calculates this value automatically and displays that value as read-only.
Loop Type	Character	A value representing the category of the protective instrument loop, based on the type of data that the sensor is measuring.	This field contains the following options: Analysis Flow Level Load Pressure Speed Temperature
Meets Architectural Constraints?	Character	A value that indicates whether the protective instrument loop's architectural constraints, specified by the standard in the Test Architectural Constraints field, meet the requirement defined by the value in the Required SIL field.	This list appears in the Calculated Results section and contains the following options: Incomplete Yes No N/A By default, this value is set to Incomplete. When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, this field is disabled and populated automatically using the following logic: If the value in the Calculated SIL Architectural Constraints field is greater than or equal to the value in the Required SIL field, this value is set to Yes. Otherwise, this value is set to No. If the value in the Test Architectural Constraints field is Not Consider, this value is set to NA.
Meets Availability Target?	Character	A value that indicates whether the protective instrument loop's availability meets the availability requirement defined in the Instrumented Function that is linked to the Protective Instrument Loop.	This list appears in the Calculated Results section and contains the following options: Incomplete Yes No N/A By default, this value is set to Incomplete. When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the Meets Availability Target field is disabled and populated automatically. After you calculate the SIL Verification results, this field is populated using the following logic: If the value in the Demand Mode field is Low Demand, and the value in the Availability field is greater than or equal to the value stored in the Availability Target field in the Instrumented Function that is linked to the Protective Instrument Loop this value is set to Yes. Otherwise, this value is set to No. If the value in the Demand Mode field is High Demand or Continuous, this value is N/A.
Meets SIL Requirement?	Character	A value that indicates whether the protective instrument loop's SIL value meets the SIL requirement defined in the Required SIL field. In order to meet the SIL requirement, the values in the following fields must be greater than or equal to the value in the Required SIL field: Achieved SIL Calculated SIL Architectural Constraints Calculated SIL Systematic Capabilities	This list appears in the Calculated Results section and contains the following options: Incomplete Yes No N/A By default, this value is set to Incomplete. When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, this field is disabled and populated automatically using the following logic: If the value in the Achieved SIL field is greater than or equal to the value in the Required SIL field, this value is set to Yes. Otherwise, this value is set to No.
Meets STR Limit?	Character	A value that indicates whether the protective instrument loop's spurious trip rate meets the spurious trip rate requirement defined in the Instrumented Function that is linked to the Protective Instrument Loop.	This list in the Calculated Results section and contains the following options: Incomplete Yes No N/A By default, this value is set to Incomplete. When the value in the SIL Verification Method field is External Calculation, the Meets STR Limit field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the Meets STR Limit field is disabled and populated using the following logic: If the inverse of the value stored in the MTTS field is greater than or equal to the value stored in the Spurious Trip Limit (per yr) field in the Instrumented Function that is linked to the Protective Instrument Loop, this value is set to No. Otherwise, this value is set to Yes. If the Protective Instrument Loop is part of a protective instrument loop template, this value is set to N/A.
Meets Systematic Capabilities?	Character	A value that indicates whether the protective instrument loop's systematic capability meets the systematic capability requirement defined in the Required SIL field.	This list appears in the Calculated Results section and contains the following options: Incomplete Yes No N/A This value is set to Incomplete by default. When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, this field is disabled and populated automatically using the following logic: If the value in the Calculated SIL Systematic Capabilities field is greater than or equal to the value in the Required SIL field, this value is set to Yes. Otherwise, this value is set to No. If the value in the Systematic Capability Validation field is False, this value is set to N/A.
Mission Time	Number	A number that represents the time that the protective instrument loop or the element will be in use before it is replaced.	This value is measured in years. This value is determined by the least mission time value among the values for all the elements of the protective instrument loop. For example, if the mission time values for the logic solver, final element, and sensor are 10 years, 5 years, and 20 years respectively, then the mission time for the entire loop is 5 years.
MTTFS	Number	A number that represents the Mean Time To Fail Spuriously (i.e., the mean time until a failure of the loop causes a process trip when a hazard was not present).	This field appears in the Calculated Results section, which is enabled or disabled based on the following criteria: When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the GE Digital APM system calculates this value automatically and displays that value as read-only. This value is measured in years.
Required SIL	Number	A number representing the SIL value that is required for the protective instrument loop.	This field is disabled and populated with the value stored in the Selected SIL Level field in the Instrumented Function that is linked to the Protective Instrument Loop.
Risk Reduction Factor	Number	A number representing the factor by which the risk should be reduced for the protective instrument loop.	This field appears in the Calculated Results section and is enabled or disabled based on the following criteria: When the value in the SIL Verification Method field is External Calculation, this field is enabled. When the value in the SIL Verification Method field is Internal Calculation, the GE Digital APM system calculates this value automatically and displays that value as read-only.
Sensor MCI	Number	A value that represents the Maintenance Capability Index.	This field contains the following options: MCI 0 (0%) : Indicates that repair actions are never performed. MCI 1 (60%) : Indicates that repair actions are effective 60 percent of the time. MCI 2 (90%) : Indicates that repair actions are effective 90 percent of the time. MCI 3 (99%) : Indicates that repair actions are effective 99 percent of the time. MCI 4 (100%) : Indicates that repair actions are always performed perfectly.
SIL Verification Method	Character	A value that represents the type of method used to calculate the SIL verification results for the protective instrument loop.	This field contains the following options: Internal Calculation : Indicates that the GE Digital APM system will calculate the SIL verification results using the IEC 61508 and the IEC 61511 functional safety standards. When this option is selected, the GE Digital APM system calculates the values in all fields in the Calculated Results section automatically and displays them as read-only. External Calculation : Indicates that you will enter SIL verification results directly into the fields on the Protective Instrument Loop datasheet. When this option is selected, all the fields in the Calculated Results section are enabled, and you can enter values directly into those fields.
Startup Time	Number	A number representing the amount of time the protective instrument loop has been bypassed since it was in the startup mode.	This value is measured in hours.
Systematic Capability Validation	Logical	A value that indicates whether the SIL value for the protective instrument loop will account for systematic capabilities, which are defined in the failure data for each protective instrument loop element.	If you select this check box, the protective instrument loop will use systematic capabilities. If you clear this check box, the protective instrument loop will not use systematic capabilities.
Test Architecture Constraints	Character	A value that indicates the level of safety certification that is associated with the elements in the protective instrument loop.	This field contains the following options: IEC 61508 : Indicates that the elements in the protective instrument loop have been certified according to the IEC 61508 standard. IEC 61511 : Indicates that the elements in the protective instrument loop have been certified according to the IEC 61511 standard. Not Consider : Indicates that the architectural constraints will not be considered in the SIL calculation.