仪表安全系统简介sis英文学习资料.pdf
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1、 ABB - Page 1 E x t e n d e d A u t o m a t i o n S y s t e m 8 0 0 x A Functional safety Engineering - Intro to SIS ABB - Page 2 Functional safetyIntro to Safety Instrumented System ?Safety Instrumented System Definition ?Safety Instrumented System Purpose ?Safety Instrumented Function ?SIS Equipme
2、nt ?Terms and Abreviations ABB - Page 3 Functional safetySafety Instrumented System Definition ?Safety Instrumented System = SIS ?IEC 61511 defines the Safety Instrumented System as: ?“Instrumented system used to implement one or more safety instrumented functions. A SIS is composed of any combinati
3、on of sensor(s), logic solver(s) and final elements(s) ?IEC 61508 does not use the term Safety Instrumented System (SIS) and instead use the term Safety Related System (SRS) to mean the same thing. ?This may change in next release of 61508 ABB - Page 4 Functional safetySIS Definition from IEC 61511
4、?Safety Instrumented Systems ?Reduce risk by decrease the likelihood of a potential hazard ?Decrease risk by reducing the magnitude of the consequence ?A SIS may be responsible for ?Shutdown function ?Permissive function ?And consequence reduction (mitigation) functions ?All these functions Reduce R
5、ISK ABB - Page 5 Functional safetySIS Definition ?A more functional definition of SIS such as: ?“A SIS is defined as a system composed of sensors, logic solvers and final elements designed for the purpose of ?1. Automatically taking an industrial process to a safe state when specified conditions are
6、 violated ?2. Permit a process to move forward in a safe manner when specified condition allow (permissive functions) ?3. Taking action to mitigate the consequences of an industrial hazard ?SIS = ”Automatic Risk Reduction Systems ABB - Page 6 Functional safetySIS Purpose ?The purpose of a SIS is to
7、reduce the risk that a process may become Hazardious to a tolerable level, ?The amount of risk reduction that an SIS can provide is represented by its safety integrtity level (SIL), which is defined as a range of probability of failure on demand. ?Safe state; state of the process when safety is achi
8、eved ?A SIS sences hazardious conditions and then take action to move the process to a safe state, preventing an unwatned accident from occuring ABB - Page 7 Functional safetySIS Safety instrumented system Temperature Transmitter Temperature Transmitter Level Switch Logic Solver Solenoid Shut-off Va
9、lve Pump Safety Instrumented System with multiple SIFs Flow TransmitterSolenoid SIF 1 SIF 2 SIF 3 SIF 4 Globe Valve ABB - Page 8 Functional safety Safety function and safety integrity from IEC 61511 ?Safety function ?Function to be implemented by an E/E/PE safety-related system, other technology saf
10、ety related system or external risk reduction facilities, which is intended to achieve or maintain a safe state for the EUC, in respect of a specific hazardous event (see 3.4.1) ?Safety integrity ?Average probability of a safety instrumented system satisfactorily performing the required safety instr
11、umented functions under all the stated conditions within a stated period of time ?Safety integrity level (SIL) ?Discrete level (one out of four) for specifying the safety integrity requirements of the safety instrumented functions to be allocated to the safety instrumented systems. Safety integrity
12、level 4 has the highest level of safety integrity; safety integrity level 1 has the lowest ABB - Page 9 Functional safety Safety function the likelihood of the safety function being achieved Determined from the risk assessment ABB - Page 10 Functional safety Safety function Safety function: In order
13、 to prevent the rupture of pressure vessel “X”, valve “Y” should open in 2 seconds when the pressure in the vessel rises to 2.6 bar. Safety integrity: The safety integrity of the safety function shall be SIL 2 Safety Integrity Level ABB - Page 11 Functional safety The essence of functional safety Fu
14、nctional safety requirements spec Functional safety requirements specification Safety integrity requirements specification Safety functions requirements specification Determined from the risk assessment Determined from the hazard analysis ABB - Page 12 Functional safety BPCS vs. SIS ?Both composed o
15、f sensors, controllers and final element ?Control loop maintain a process variable within prescribed limits ?SIS monitors a process variable and take action when required ?Differences in dynamics ?BPCS - Signals moves often, failure can be detected by plant personnel ?SIS Signals may be motionless f
16、or years (normally static), failures difficult to detect ABB - Page 13 Functional safety SIS Engineering Requirement ?Design to fail-safe ?Design diagnostics to automatically detect fail-danger ?Design manual test procedures to detect fail-danger ?Design to meet international and local standards ?Al
17、so ?Satisfy the functional requirement ?Satisfy performance requirement ABB - Page 14 Functional safetySIS - SIF ?1 SIS can have 1 or more SIF(s) ?Multiple SIFs can include common equipment ?If an equipment is in more than 1 SIF it need to be designed for the highest SIL requirement. ABB - Page 15 F
18、unctional safetySIF Safety Instrumented Function Temperature Transmitter Temperature Transmitter Logic Solver Solenoid Shut-off Valve ?Safety instrumented function (SIF) (From IEC 61511 1) ?Safety function with a specified safety integrity level which is necessary to achieve functional safety and wh
19、ich can be either a safety instrumented protection function or a safety instrumented control function ?Related to a specific hazardous event ABB - Page 16 Functional safetySIF Safety Instrumented Function ?SIF is an action a SIS takes to bring the process or the equipment under control to a safe sta
20、te. ?This function is a single set of actions that protects against a single specific hazard. ?A SIS is a collection of sensors, logic solvers and actuators that execute one or more safety instrumented functions (SIFs) that are implemented for a common purpose. ?SIF often refers to the equipment tha
21、t carries out the single set of actions in response to the single hazard, as well to the particular set of actions itself ABB - Page 17 Functional safetySIF Examples ?SIF 1: Open sprinkler valve when a flame is detected in order to reduce the size of fire ?SIF 2: Close valve to stop material flow in
22、to tank to prevent spillage of high level is detected, which may result in environmental damage ?SIF 3:Cut of fuel in an industrial burner when fuel pressure is to low to sustain combustion, which may result in flameout and possible explosion due to fuel buildup in the combustion chamber ABB - Page
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