# Motors And Transformers

45 Questions | Total Attempts: 635  Settings  This quiz is designed to evaluate one's knowledge of motors and transformers commonly used in industry. It is also designed to evaluate knowledge of basic AC and DC electrical fundamentals.

• 1.
What do DC motors have a that AC motors do not? ____, ____, ____, ____, and a ____.
• 2.
The magnetically operated device that can change values of voltage, current, and impedance without changing the frequncy is the
• A.

Converter

• B.

Inverter

• C.

Transformer

• D.

Transistor

• 3.
In a transformr, the turns of the primary wire compared to the turns of the secondary wire is called the ______ ratio.
• A.

Isolation

• B.

Step-up

• C.

Step-down

• D.

Turns

• 4.
In a transformer, even when no load is connected, there is a small current required to magnetize the core.  It is called the ____ current.
• A.

Excitation

• B.

Primary

• C.

Secondary

• D.

Isolation

• 5.
A transformer in which the secondary voltage is less than the primary voltage is called a ____ transformer.
• A.

Step-up

• B.

Step-down

• C.

Isolation

• D.

Auto

• 6.
The industrial use transformer that normally has 240v or 480v primary and a 120 v secondary is called a(n) ____ transformer.
• A.

Auto

• B.

Distribution

• C.

Isolation

• D.

Control

• 7.
A wye-delta transformer has its____ connected as a wye and its connected as a delta.
• A.

Secondary, primary

• B.

Primary, secondary

• 8.
A delta-wye transformer has its____ connected as a delta and its connected as a wye.
• A.

Secondary, primary

• B.

Primary, secondary

• 9.
An open delta connection is made using ____ single-phase transformers.
• A.

One

• B.

Two

• C.

Three

• D.

Four

• 10.
When connecting three transformers for three phase use with the delta secondary, a voltage test should be done before closing the secondary.  The correct voltage reading is
• A.

The rated secondary voltage value

• B.

Twice the rated secondary voltage value

• C.

Zero volts

• D.

The sum of the the three transformer primaries

• 11.
When using an open delta with a center tapped transformer, on wire is the "high leg."  The high leg is the one that
• A.

Has the highest voltage measured to ground

• B.

Has the lowest voltage measured to ground

• C.

Has the most amperage

• D.

Is mounted highest on the panel

• 12.
In an open delta with single phase loads, the high leg must be identified by
• A.

Using an orange wire

• B.

Tagging

• C.

Both a and b above

• D.

Either a or b above

• 13.
A transformer has a 240v primary and a 60v secondary.  With a 5 ohm load connected, what is the primary volt amps?
• A.

12 amps

• B.

3 amps

• C.

0.75 amps

• D.

48 amps

• 14.
A transformer has a 240v primary and a 120v secondary.  With a 30 ohm load connected, what is the primary volt amps?
• A.

4

• B.

8

• C.

480

• D.

960

• 15.
A transformer supplying a house with 120 / 240 volts has a secondary whic is center tapped.  The conductor connected to the center is called the ____ conductor.
• A.

Equipment ground

• B.

Hot

• C.

Neutral

• D.

Ungrounded

• 16.
In an isolation transformer, all windings will have the same number of volts per turn.
• A.

True

• B.

False

• 17.
When single phase loads are tied to a three phase transformer, the phase currents of the transformer will be automatically balanced.
• A.

True

• B.

False

• 18.
A transformer in which the primary and secondary are phsically separated and not connected by a conductor is called a(n) ____ transformer.
• A.

Isolation

• B.

Step up

• C.

Step down

• D.

Turns

• 19.
A transformer tape wound core is assembled by
• A.

Stacking small indivisual sheets of metal

• B.

Winding a long continuous tape of metal into a spiral

• C.

Casting a solid core and wrapping it with tape

• D.

Bolting together two halves

• 20.
A transformer that does not isolate the output from the input is called a(n) ____ transformer.
• A.

Distribution

• B.

Step up

• C.

Auto

• D.

Control

• 21.
The transformer winding which is the output winding is called the
• A.

Primary

• B.

Secondary

• C.

Tertiary

• D.

Tapped

• 22.
The basis for understanding magnetic principles is the ____ theory of magnetism.
• 23.
Three naturally magnetic metals are ____, ____, and ____.
• 24.
When atoms in magnetic materials become ions, magnetic regions called ____ ____ are produced
• 25.
Four effects that can demagnetize a magnet are ____, ____, ____, and ____.
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