ISO 13577-4:2014 工業炉および関連する処理装置—安全性—パート4：保護システム | ページ 6

3.1

final element

part of a protective system which implements the physical action necessary to achieve a safe state

Note 1 to entry: Examples are valves, switch gear, motors including their auxiliary elements, for example, a solenoid valve and actuator if involved in the safety function.

[SOURCE: IEC 61511-1:2003, 3.2.24 modified:"instrumented system" had been changed to read"protective system" in the definition.]

3.2

flame detector device

device by which the presence of a flame is detected and signaled

Note 1 to entry: It can consist of a flame sensor, an amplifier, and a relay for signal transmission.

[SOURCE: ISO 13574:—²⁾, 2.65, modified: The second sentence in the original definition had been presented as in the Note.]

3.3

functional safety

capability of a protective system or other means to reduce risk, to execute the actions required for achieving or maintaining a safe state for the process and its related equipment

[SOURCE: ISO 13574:—²⁾, 2.73]

3.4

logic function

function that performs the transformations between input information (provided by one or more input functions or sensors) and output information (used by one or more output functions or final elements)

Note 1 to entry: Logic functions are executed by the logic solver of a protective system.

[SOURCE: IEC 61511-1:2003, 3.2.39, modified —"input functions" had been changed to read"input functions or sensors" and"output function" had been changed to read"output function or final elements" in the definition, and the second sentence in the original definition had been deleted; Note has been added.]

3.5

logic solver

portion of a protective system that performs one or more logic function(s)

Note 1 to entry: Examples are electrical systems, electronic systems, programmable electronic systems, pneumatic systems, and hydraulic systems. Sensors and final elements are not part of the logic solver.

[SOURCE: IEC 61511-1:2003, 3.2.40 modified:"either a BPCS or SIS" had been changed to read"a protective system" in the definition; Note 1 in the original definition had been deleted.]

3.6

manual reset

action after a lockout of a safety device (e.g. automatic burner control) carried out manually by the supervising operator

[SOURCE: ISO 13574:— ³ , 2.107]

3.7

performance level

pl

discrete level used to specify the ability of safety-related parts of control systems to perform a safety function under foreseeable conditions

[SOURCE: ISO 13849‑1:2006, 3.1.23]

3.8

product standard

standard for products and devices which are listed in ISO 13577 (all parts) except this part of ISO 13577

[SOURCE: ISO 13574:—³⁾, 2.135 modified:"ISO 13577‑4" has been changed to read"this part of ISO 13577" in the definition.]

3.9

programmable logic control

PLC

electronic device designed for control of the logical sequence of events

[SOURCE: ISO 13574:—, 2.125]

3.10

protective system

instrumented system used to implement one or more safety-related instrumented functions which is composed of any combination of sensor(s), logic solver(s), and final elements (for example, see Figure 2)

Note 1 to entry: This can include safety-related instrumented control functions or safety-related instrumented protection functions or both.

[SOURCE: ISO 13574:—, 2.138]

3.11

safety bus

bus system and/or protocol for digital network communication between safety devices, which is designed to achieve and/or maintain a safe state of the protective system in compliance with IEC 61508 (all parts):2010 or IEC 60730-2-5

[SOURCE: ISO 13574:—, 2.164]

3.12

safety device

device that is used to perform protective functions, either on its own or as a part of a protective system

Note 1 to entry: Examples are sensors, limiters, flame monitors, burner control systems, logic systems, final elements, and automatic shut-off valves.

3.13

safety integrity level

SIL

discrete level (one out of a possible four), corresponding to a range of safety integrity values, where safety integrity level 4 has the highest level of safety integrity and safety integrity level 1 has the lowest

Note 1 to entry: The target failure measures for the four safety integrity levels are specified in IEC 61508-1:2010, Tables 2 and 3.

Note 2 to entry: Safety integrity levels are used for specifying the safety integrity requirements of the safety functions to be allocated to the E/E/PE safety-related systems.

Note 3 to entry: A safety integrity level (SIL) is not a property of a system, subsystem, element, or device. The correct interpretation of the phrase"SIL n safety-related system" (where n is 1, 2, 3, or 4) is that the system is potentially capable of supporting safety functions with a safety integrity level up to n.

[SOURCE: IEC 61508-4:2010, 3.5.8]

3.14

sensor

device that produces a signal based on a process variable

3.15

system for permanent operation

system, which is intended to remain in the running position for longer than 24 h without interruption

[SOURCE: IEC 60730-2-5:2009, 2.5.101]

3.16

system for non-permanent operation

system, which is intended to remain in the running position for less than 24 h

[SOURCE: IEC 60730-2-5:2009, 2.5.102]

3.17

systematic capability

measure (expressed on a scale of SC 1 to SC 4) of the confidence that the systematic safety integrity of an element meets the requirements of the specified SIL, in respect of the specified element safety function, when the element is applied in accordance with the instructions specified in the compliant item safety manual for the element

Note 1 to entry: Systematic capability is determined with reference to the requirements for the avoidance and control of systematic faults (see IEC 61508-2 and IEC 61508-3).

Note 2 to entry: What qualifies as a relevant systematic failure mechanism depends on the nature of the element. For example, for an element comprising solely software, only software failure mechanisms will need to be considered. For an element comprising hardware and software, it is necessary to consider both systematic hardware and software failure mechanisms.

Note 3 to entry: A systematic capability of SC N for an element, in respect of the specified element safety function, means that the systematic safety integrity of SIL N has been met when the element is applied in accordance with the instructions specified in the compliant item safety manual for the element.

[SOURCE: ISO 13574:—, 2.183]