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An SIS is intended to perform specific control functions to prevent unsafe process operations when unacceptable or dangerous conditions occur. Because of its criticality, safety instrumented systems must be independent from all other control systems that control the same equipment, in order to ensure SIS functionality is not compromised.
A risk assessment effort yields a target SIL for each safety function. For any given design the achieved SIL is evaluated by three measures: 1. Systematic Capability (SC) which is a measure of design quality. Each device in the design has an SC rating. The SIL of the safety function is limited to smallest SC rating of the devices used.
The STO function is the most common and basic drive-integrated safety function. It ensures that no torque-generating energy can continue to act upon a motor and prevents unintentional starting. [ 1 ]
As such, safety relays monitor a specific function. When connected to other safety relays, they guarantee full monitoring of a plant or machine. [1] They meet the requirements of EN 60947-5-1, EN 60204-1 and VDE 0113-1. [5] Furthermore, there are many variants of safety relays, which are suitable for various machinery applications.
Although functionally separate, process control and shutdown systems are usually interfaced under one system, called an integrated control and safety system (ICSS). Shutdown systems typically use equipment that is SIL 2 certified as a minimum, whereas control systems can start with SIL 1. SIL applies to both hardware and software requirements ...
In functional safety, safety integrity level (SIL) is defined as the relative level of risk-reduction provided by a safety instrumented function (SIF), i.e. the measurement of the performance required of the SIF.
An industrial control system (ICS) is an electronic control system and associated instrumentation used for industrial process control. Control systems can range in size from a few modular panel-mounted controllers to large interconnected and interactive distributed control systems (DCSs) with many thousands of field connections.
Automotive Safety Integrity Level (ASIL) is a risk classification scheme defined by the ISO 26262 - Functional Safety for Road Vehicles standard. This is an adaptation of the Safety Integrity Level (SIL) used in IEC 61508 for the automotive industry. This classification helps defining the safety requirements necessary to be in line with the ISO ...