Glossary

Condition-based maintenance is maintenance whose timing is decided by the assessed condition of the equipment, from inspection, testing or monitoring, instead of by elapsed time or use alone.

Condition of maintenance is the state of electrical equipment with respect to the maintenance that the manufacturer's instructions and the applicable standards call for; the NFPA electrical standards use the term when the condition of equipment bears on the safety of the people who operate or work on it.

Corrective maintenance is work that restores equipment after a fault, defect or deficiency has been found, as distinct from work scheduled to prevent one.

An electrical maintenance program is the documented set of responsibilities, equipment inventory, priorities, procedures, intervals, inspections, tests and records through which the owner of electrical equipment keeps that equipment in a known condition; NFPA 70B abbreviates the term as EMP.

A maintenance interval is the planned span of time or use between successive performances of a maintenance task on an item; it is set from the manufacturer's instructions, the condition and criticality of the equipment and its operating environment.

The P-F curve is a reliability model that plots the condition of an item against time from the point at which a potential failure first becomes detectable (P) to the point of functional failure (F); the P-F interval between the two bounds how often an inspection must take place to find the deterioration in time.

Predictive maintenance schedules work from measured trends in the condition of equipment, such as temperature, insulation resistance, partial discharge or vibration, rather than from a fixed calendar interval alone.

Preventive maintenance is inspection, servicing and testing carried out at planned intervals of time or use so that equipment stays in its intended condition and deterioration is found before it causes a failure.