Exam 3: The Control Transformer, Relays, Contactors, and Motor Starters

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Relays are electromechanical switches that lack auxiliary contacts.

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The ____________________ rating of control transformers generally ranges from 0.75 kilovolt-amperes, or 75 volt-amperes, to 1 kilovolt-ampere, or 1000 volt-ampere.

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NEC Section 430.72(C) lists requirements for the protection of transformers employed in motor control circuits.

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Control transformers generally have ____ terminals connected to the primary and secondary leads.

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What are ghost voltages?

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What problems can insufficient coil voltage cause?

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How are control transformers protected?

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It is a common practice to not ground one side of the control transformer. This is generally referred to as a ____ system.

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Mechanically held contactors and relays are often referred to as ____ contactors or relays.

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Most industrial motors operate on voltages that range from 240 to 480 volts.

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The greatest difference between relays and contactors is the fact that contactors are equipped with large contacts that are intended to connect high-current loads to the power line.

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Solid-state relays that are intended to connect alternating current loads to the line use a device called a(n) ____________________.

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The number of ____________________ refers to the load contacts and does not include the number of control or auxiliary contacts.

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