Question 1

Most industrial and commercial air conditioning systems operate on 240 or 480 volts.

Accepted Answer

Most industrial and commercial air conditioning systems operate on higher voltage systems such as 240 or 480 volts.

Question 2

The secondary is the winding that is connected to the power source and brings power to the transformer.

Accepted Answer

The primary winding is the winding that is connected to the power source and brings power to the transformer. The secondary winding is the winding that is connected to the load and receives power from the transformer.

Question 3

It is generally assumed that the power out of the transformer is ____ the power being put into the transformer.&#10;A) greater than&#10;B) less than&#10;C) equal to&#10;D) unrelated to

Accepted Answer

The power output of a transformer is generally assumed to be equal to the power input, accounting for the principle of conservation of energy, although in practical applications, some power is lost due to inefficiencies.

Question 4

An ohmmeter is generally used to test the windings of the transformer.

Accepted Answer

An ohmmeter is commonly used to check the continuity and resistance of the windings in a transformer.

Question 5

The transformer operates by a temperature gradient.

Accepted Answer

The transformer operates by electromagnetic induction, not temperature gradient.

Question 6

Most residential air conditioning systems operate on a control voltage of ____.&#10;A) 12 volts AC&#10;B) 24 volts AC&#10;C) 36 volts AC&#10;D) 48 volts AC

Accepted Answer

Most residential air conditioning systems operate on a control voltage of 24 volts AC. This voltage is used to control the operation of the system's components, such as the compressor, fan, and thermostat. It is low enough to be safe for humans to handle, but high enough to reliably operate the equipment.

Question 7

A transformer is a device that can change values of AC voltage and current without a change of ____.&#10;A) temperature&#10;B) wavelength&#10;C) efficiency&#10;D) frequency

Accepted Answer

A transformer can change the voltage and current levels in an AC circuit without changing the frequency. This is a result of the transformer's ability to transfer energy between two coils by way of a magnetic field, which induces a voltage in the secondary coil based on the ratio of turns in the primary and secondary coils. Therefore, the frequency of the AC power input remains constant at the output of a transformer.

Question 8

If the transformer is to be used to change 480 volts to 120 volts, the primary windings ____.&#10;A) will be connected in series&#10;B) will go through the secondary windings&#10;C) will be connected in parallel&#10;D) will have the leads crossed

Accepted Answer

The primary windings will be connected in series to handle the higher voltage of 480 volts, effectively stepping it down to 120 volts in the secondary windings. This is a basic principle of transformer operation, where the ratio of primary to secondary windings determines the voltage transformation.

Question 9

The output voltage of the transformer should be tested with a(n) ____.&#10;A) DC voltmeter&#10;B) ohmmeter&#10;C) AC voltmeter&#10;D) ammeter

Accepted Answer

The output voltage of a transformer is an AC voltage, so it should be tested with an AC voltmeter. DC voltages can damage the voltmeter and an ohmmeter measures resistance, not voltage. An ammeter measures current, not voltage.

Question 10

Control transformers are used to change the value of line voltage to the value needed for the control circuit.

Accepted Answer

Control transformers are designed to step down the line voltage to a lower value suitable for use in the control circuit. This allows the use of smaller and more efficient components in the control circuit.

Deck 25: The Control Transformer