Trip

The shutdown is activated automatically by the control/monitoring system.

Source: API STD 689, Collection and Exchange of Reliability and Maintenance Data for Equipment, First Edition, July 2007. Global Standards

shutdown of machinery from normal operating condition to full stop

Note 1 to entry: Two types of shutdown can be identified:

a) Trip: the shutdown is activated automatically by the control/monitoring system.

• Real trip: the shutdown is activated as a result of a monitored (or calculated) value in the control system

exceeding a pre-set limit.

• Spurious trip: unexpected shutdown resulting from failure(s) in the control/monitoring system or error(s)

imposed by on control/monitoring system originating from the environment or people.

b) Manual shutdown: the machinery is stopped by an intended action of the operator (locally or form the

control room).

Note 2 to entry: Sometimes statements like “equipment trip” or “spurious trip” can be misleading terminology

used for failures causing (rotating) equipment shutdown, especially when it is treated as failure mode in reliability

data or modelling. A failure mechanism (see Table B.2 of ISO 14224[15]) can be of various types (e.g. mechanical,

instrument) and should not be mixed with the term failure modes (of which one is spurious trip). Failure modes

are not necessarily instrument-related failures, but could be mechanical failures. See for example failure modes

in Table B.6 of ISO 14224[15] for rotating equipment.

[SOURCE: ISO 14224]

Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards

Glossary