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31 Cards in this Set
- Front
- Back
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A _______ is an electric device that uses electro-magnetism to change voltage from one level to another or to isolate one voltage from another.
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Transformer |
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_______ is the property of a device or circuit that causes it to store energy in a magnetic field.
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Inductance |
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In a transformer, the conductor is the wire making up the coil.
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True
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The closed, laminated core gives a path of low ______for the flux to flow, which aligns the flux and allows the maximum number of conductors to be cut
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Reluctance |
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________ is the ability of an inductor in a circuit to generate inductive reactance, which opposes change in the circuit.
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Self-induction
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A magnetizing current is also known as a(n)______current.
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exciting
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The turns ratio of a transformer which is rated for a primary voltage of 2400 volts and has a secondary rating of 120 volts is ______?
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20 to 1 |
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If a transformer has a turn ratio of 35 to 2 and the secondary voltage is 24v, how much voltage is applied to the primary?
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430v |
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A(n)______ is an extra electrical connection on a transformer coil that allows a varying number of turns of a coil to be part of the circuit.
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Coil Tap |
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What is the purpose of the taps that are used on some transformers?
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Taps allow for the output voltage of the transformer to be raised or lowered.
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With careful design, it is possible to completely eliminate transformer power loss.
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False |
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_________is power loss in a transformer due to currents induced in the metal field structure from the changing magnetic field.
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Eddy current loss
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__________ is the property of ferromagnetic materials where the magnetic induction of a coil lags the magnetic field that is charging the coil
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Hysteresis
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Transformer mutual inductance is also referred to as a______?
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coefficient of coupling
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Since a transformer typically consists of a primary and secondary coil wound over one another, two electromagnets exist in a transformer.
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True |
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Taps are typically located on the secondary windings of a transformer.
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False |
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A shell-type transformer has an equal number of legs and windings.
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False |
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In a dry-type transformer, air is used to cool the coils.
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True |
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Liquid - immersed transformers are typically immersed in _____?
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oils |
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Askarels are often used instead of mineral oil as a cooling fluid in newer transformers.
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False |
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The temperature rise in a transformer is the difference between the hot-spot maximum core temperature and the average operating temperature.
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False |
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A(n) ______is a pipe, 4” in diameter or greater, that extends a few feet above the cover of a transformer and is curved toward the ground at the outlet end of the pipe.
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explosion vent
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A(n)_______is a transition device between underground cable and lines.
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Pothead |
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Electrical power circuits must be insulated by ______ where they enter the transformer tank?
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Bushings |
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Liquid-filled transformers are fitted with a thermometer to measure the temperature at the top of the fluid.
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True |
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A sampling valve draws liquid from the lowest point in the tank
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True |
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All transformers hum when energized.
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True |
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.Liquid-filled transformers use a level gauge that has a mark at the correct level for fluid at _______ to ensure that fluid does not overflow or reach a dangerously low level.
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25 degrees C
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The _____ determines if a device is a step-up or step-down transformer.
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turns ratio between the coils and the primary winding's physical relationship to the core
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Transformers are rated by their capacity in ________?
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kilovolt amps (kVA)
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Power consumed by a load is measured in ______?
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Watts |
