Glossary of Emergency Shutdown System (ESD)

Mention different Glossary of Emergency Shutdown System (ESD) or Safety Instrumented Systems (SIS) most widely used definitions.

Emergency Shutdown System (ESD)


The Probability that a system will be able to perform its designated function when required for use.

Electromagnetic Compatibility

The ability of equipment to function satisfactorily in its electromagnetic environment without introducing intolerable disturbances to that environment or to other equipment.


The capability to go to a predetermined safe state in the event of specific malfunction.

Fault Tolerance

Built-in capability of a system to provide continued correct execution of its assigned function in the presence of a limited number of hardware or software faults.

Safety Integrity

The probability of a safety related system satisfactorily performing the required safety functions under all stated conditions within a stated period of time.

Safety Integrity Level

Discrete level for specifying the safety integrity requirements of the safety functions to be allocated to safety related systems in accordance with IEC-61508

Voting System

Redundant system that requires at least “m” of the “n” channels/devices (m out of n) to be in agreement before the system can take an action.

Galvanic Isolation

The isolation of functional sections of electrical systems or electrical signals so that charge-carrying particles can not move from one section to another, i.e. there is no electrical current flowing directly from one section to next.

However, energy and/or information can still be exchanged between the sections by capacitance,induction, electromagnetic waves, or mechanical means.

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