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Define a contactor.

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A contactor is a mag...

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Contactor contacts that are badly pitted can cause the motor to burn out.

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What causes the overload of a starter to open and disable the power circuit?

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This occurs because ...

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Define a pilot-duty relay.

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A pilot-duty relay is a low vo...

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Why should a technician not file the rough surfaces of a contactor's contacts?

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The base metal will be exposed and the contacts will deteriorate.

The most common material used on the surface of contacts is ____________________.

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Why is a starter equipped with overload protection when the circuit already has a fuse or circuit breaker?

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The fuse or circuit ...

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Define a relay.

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A relay is a magnetically controlled set of contacts that are not replaceable.

When a contactor's coil is energized, how much resistance should be measured between terminal "L1" and terminal "T1"?


A) zero ohms
B) 50-3000 ohms
C) 5000-6000 ohms
D) infinite

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The best way to repair a large contactor is by the replacement of ____________________.

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component ...

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What effect would a loose connection have on a solder pot overload device?

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Heat produced by the...

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A solder pot is part of a ____.


A) one-time fuse
B) resettable circuit breaker
C) time-delay fuse
D) plumber's tool kit

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Standards for motor overload protection are set by the ____.


A) United States Department of Transportation
B) National Electrical Code
C) Environmental Protection Agency
D) American National Standards Institute

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If a relay starts the indoor fan in the cooling mode of a central air-conditioning system, it must be able to withstand the ____________________  of the fan motor on start-up.

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Bimetal and solder pot overload devices are thermally operated.

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Why do many starters have manual resets?

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If the starter resets automatically, the...

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Define a motor starter.

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A motor starter is a relay or contactor with built-in overload cutouts.

A sure sign of contact failure is discoloration on the contact surfaces.

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The sun shining on a distribution panel has no effect on the breakers in the panel.

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A common practice in condensing units is to use a contactor with only one set of contacts opening only one side of the power to the unit. This is to ____.


A) reduce the cost of the contactor
B) make it easier to wire the unit
C) teach the service technician not to put hands in the unit with the power on
D) provide off-cycle heat to the compressor

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Showing 1 - 20 of 31

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