CONTROL EQUIPMENT FOR MOTORS

251. Electric-controller terminology

Ambient temperature. The temperature of the medium such as air, water, or earth into which the heat of the equipment is dissipated. For self-ventilated equipment, the ambient temperature is the average ^[1] temperature of the air in the immediate neighborhood of the equipment. For air- or gas-cooled equipment with forced ventilation or secondary water cooling, the ambient temperature is taken as that of the ingoing air or cooling gas. For self-ventilated enclosed (including oil-immersed) equipment considered as a complete unit, the ambient temperature is the average ^[1] temperature of the air outside the enclosure in the immediate neighborhood of the equipment.

Apparatus. A term said to describe the enclosure, the enclosed equipment, and attached appurtenances.

Auxiliary contacts of a switching device. Those contacts which in addition to the main-circuit contacts function with the movement of the latter.

Combination controller. A full magnetic or semimagnetic controller with additional externally operable disconnecting means contained in a common enclosure. The disconnecting means may be a circuit breaker or a disconnect switch. Combination starters are specific forms of combination controllers.

Contactor. A two-state (on-off) device for repeatedly establishing and interrupting an electric power circuit. Interruption is obtained by introducing a gap or a very large impedance.

Continuous duty. A duty that demands operation at substantially constant load for an indefinitely long time.

Control circuit of a control apparatus or system. That circuit which carries the electric signals...