408 Electrical Power Systems Technology
electric power circuit.
Controller—A device or group of devices that systematically controls the
delivery of electric power to the load or loads connected to it.
Disconnect—A control device or group of devices that will open, so that
electrical current in a circuit will be interrupted.
Drum Controller—A of electrical contacts mounted on the surface of set
a rotating cylinder. It is usually used for controlling the on-off for-
ward-reverse condition of a load.
Electronic Control—A usually solid-state device that performs part of the
control function of a system.
Full Voltage Control—A control system that connects equipment directly
across the power lines when the equipment is started.
Fuse—A cuit-protection device that disconnects a circuit when an over-cir
current condition occurs. It is self-destructing and must be replaced.
Horsepower—The power output or mechanical work rating of an electri-
cal motor.
Jogging—Momentary operation that causes a small movement of the load
that is being controlled.
Magnetic Contactor—A contactor which is operated electromagnetically
and usually controlled by pushbuttons activated by an operator.
Manual Controller—An electric control device that functions when oper-
ated by mechanical means, usually by an operator.
Master Switch—A switch that controls the power delivered to other parts
of a system.
Motor—A device (mechanical load) for converting electrical power to me-
chanical power in the form of rotary motion.
Multispeed Starter—An electrical power-control device that provides for
varying the speed of a motor.
Overload Relay—Overcurrent otection for a load. While it is in operation, pr
it maintains the interruption of the load from the power supply until
it is reset or replaced.
Overload Relay Reset—A pushbutton that is used to reset a thermal over-
load relay after the relay has been overloaded.
Pilot Device—A control device that directs the operation of another device
or devices.
Plugging—A braking method that causes a motor to develop a retarding
force in the reverse direction.
Pushbutton—A button-type control switch that is manually operated for
actuating or disconnecting some load device.