Two overload relays used to protect motors are thermal and _ overload relays.Īmbient temperatures, full-load current rating, and _ must be known when selecting the overloads for a motor starter.Īn inherent motor protector is designed to protect a motor from _? The main difference between a contactor and a motor starter is the addition of _ to the motor starter. The current rating of a contactor or motor starter is the rating for _? The power rating of a contactor or motor starter _ as the NEMA number (size 1, 2, etc.) of the contactor or motor starter increases. _ are used to help confine, divide, and extinguish arcs for each set of contacts.
_ arcs are the most difficult to extinguish on a set of contacts. _ power line(s) must be broken when using a contactor to control a 3Φ load.
Forward and reverse motor starter with timer diagram manual#
Manual motor starters are used in application such as air compressors, conveyor systems, and _?Ī _ overload measures the strength of the magnetic field around the wire instead of converting the current into heat. NEMA Type _ enclosures are intended for indoor use primarily to provide a degree of protection against human contact with the enclosed equipment in locations where unusual service conditions do not exist. _ contacts are contacts that break the electrical circuit in two places. _ temperature is the temperature of the air surrounding a motor.Ī _ alloy is a metal that has a fixed temperature at which it changes directly from a solid to a liquid state.Ī starter may be reset after an _ is removed.Įnclosures provide _ and electrical protection for the operator and the starter.Ī _ is a control device that uses pushbuttons to energize or de-energize the load connected to it. Overload protection devices are required by the _? The main device in an overload relay is the _?Ī manual starter is a _ with an added overload protection device. Manual contactors are normally used with _ circuits and resistance loads. The three stages that a motor must go through in normal operation are resting, starting, and _?įuses or _ are used to protect a motor against very high currents, short circuits, or a ground fault.Ī 120 V, 1Φ power source has one hot wire and _ neutral wire(s).Ī 230 V, 1Φ power source has two hot wires and _ neutral wire(s).Ī 3Φ power source has _ hot wires and zero neutral wires.Ī _ is a device that is used only periodically to remove electrical circuits from their supply source. Manual starters are selected based on phasing, number of poles, voltage, starter size, and _?Ī _ is a condition that occurs when a motor is loaded so heavily that the motor shaft cannot turn. _ interlocked contactors are two contactors that are connected in such a way that both sets of contacts cannot be closed at the same time. Has a higher contact rating in a smaller space.Ĭopper contacts have been replaced with _ alloy contacts because of the problems of using copper with knife switches.Ī _ diagram shows the connection and placement of an installation or its component devices or parts. One of the advantages of using a double-break contact instead of a single-break contact is that a double-break contact _? When motors were first introduced, they were started and stopped by _?
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