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General Terms and Definitions
Adjustable rating plug
A component which plugs into a trip unit, establishing the ampere rating of a circuit breaker.
Ambient temperature
Refers to the temperature of the air immediately surrounding a device under test.
Arcing contact
Auxiliary contacts designed to prevent the main contacts from being damaged. When opening, the main contacts part first and then the arcing contacts part, drawing the arc across them. When closing, the arcing contacts make first, again drawing the arc across them. This prevents the main contacts from carrying the arc and preserves them.
Automatic reset
Device that will automatically open an overload circuit. It will also automatically close or complete the circuit after a period of time. If the overload is still present, the device will continue to cycle until either the power or the overload is removed.
Acceptance Test
A calibration and functional test of a new or replacement equipment to ensure it is in proper working order prior to installation.
Alternating Current (AC)
An electric current that reverses its direction many times a second at regular intervals.
Ammeter
An instrument for measuring the flow of electrical current in amperes. Ammeters are always connected in series with the circuit to be tested.
Ampacity
The maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration.
Ampere-Hour (Ah)
A unit of measure for battery capacity. It is obtained by multiplying the current (in amperes) by the time (in hours) during which current flows. For example, a battery which provides 5 amperes for 20 hours is said to deliver 100 ampere - hours.
Ampere (A)
A unit of measure for the intensity of an electric current flowing in a circuit. One ampere is equal to a current flow of one coulomb per second.