Unit 19 Vocabulary Flashcards
Contactor
A larger version of the relay. It can be repaired or rebuilt and has movable and stationary contacts.
External motor protection
Motor overload protection that is mounted on the outside of the motor.
Inherent motor protection
This is provided by internal protection such as a snap-disc or a thermistor.
Magnetic overload (protection)
This protection reads the actual current draw of the motor and is able to shut it off based on actual current, versus the heat-operated thermal overloads, which are sensitive to the ambient heat of a hot cabinet.
Manual reset
A safety control that must be reset by a person, as opposed to automatically reset, to call attention to the problem. An electrical breaker is a manual reset device.
Motor starters
Electromagnetic contactors that contain motor protection and are used for switching electric motors on and off.
National Electrical Code (NEC)
A publication that sets the standards for all electrical installations, including motor overload protection.
Pilot duty relay
A small relay that is used in control circuits for switching purposes. It is small and cannot take a lot of current flow, such as to start a motor.
Relay
A small electromagnetic device used to control a switch, motor, or valve.
Solder pot
A device using a low-melting solder and an overload heater sized for the amperage of the motor it is protecting. The solder will melt, opening the circuit when there is an overload. It can be reset.
Time-delay relay
A device that prevents a component from starting for a prescribed time. For example, many systems start the fans and use a time delay relay to start the compressor at a later time to prevent too much inrush current.
