Category: Electric Motors

Compressor Motor Relays

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Compressor Motor Relays

A hermetic compressor motor relay is an automatic switching device designed to disconnect the motor start winding after the motor has come up to running speed (see Fig. 7-29). The two types of motor relays used in refrigeration and air-conditioning compressors are the current and the potential type.

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Permanent split-capacitor motor

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Permanent split-capacitor motor

The permanent split-capacitor (PSC) motor is used in compressors for air-conditioning and refrigeration units. It has an advantage over the capacitor-start motor inasmuch as it does not need a centrifugal switch with its associated problems. The PSC motor has a run capacitor in series with the start winding. Both run capacitor and start winding remain […]

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Motor Reversibility

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An induction motor will not always reverse while running. It may continue to run in the same direction, but at a reduced efficiency. An inertia-type load is difficult to reverse. Most motors that are classified as reversible while running will reverse with a non-inertialtype load. They may not reverse if they are under no-load conditions […]

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Capacitor-start motor

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Capacitor-start motor

The capacitor motor is slightly different from a split-phase motor. A capacitor is placed in the path of the electrical current in the start winding (see Fig. 7-13). Except for the capacitor, which is an electrical component that slows any rapid change in current, the two motors are same electrically. A capacitor motor can usually […]

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Repulsion-start induction-run motor

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Repulsion-start induction-run motor

The repulsion-induction motor starts on one principle of operation and, when almost up to speed, changes over to another type of operation. Very high twisting forces are produced during starting by the repulsion between the magnetic pole in the armature and the same kind of pole in the adjacent stator field winding. The repulsing force […]

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Getting the Motor Started

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Getting the Motor Started

One of the most important parts of the single-phase electric motor is the start mechanism. A special type is needed for use with single-phase motors. A centrifugal switch is used to take a start winding out of the circuit once the motor has come up to within 75 percent of its run speed. The split-phase, […]

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Split-phase motor

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Split-phase motor

The field of a single-phase motor, instead of rotating, merely pulsates. No rotation of the rotor takes place. A single-phase pulsating field may be visualized as two rotating fields revolving at the same speed, but in opposite directions. It follows, therefore, that the rotor will revolve in either direction at nearly synchronous speed, if it […]

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Motors Uses on HVAC

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Motors Uses on HVAC

As previously mentioned, this type of motor is used as a fan motor in refrigerators and freezers and in some types of air-conditioning equipment where the demand is not too great. It can also be used as part of a timing device for defrost timers and other sequenced operations. The fan and motor assembly are […]

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Motors

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Motors

Most AC motors are of the induction type. They are, in general, simpler and cheaper to build than equivalent DC machines. They have no commutator, slip rings, or brushes, and there is no electrical connection to the rotors. Only the stator winding is connected to the AC source, and, then, as their name implies, induction […]

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