313D Electrical Schematics and Controls 2

Question 1

In a ladder diagram, what does a normally closed (NC) contact symbol represent?

Accepted Answer

A contact that is closed during normal de-energized state

Answer

A normally closed contact is closed (conducting) when the coil controlling it is de-energized, and opens when the coil is energized.

Question 2

What is the purpose of a time-delay relay (TDR) in an AC system schematic?

Accepted Answer

To prevent short cycling by delaying compressor restart

Answer

A time-delay relay prevents short cycling by enforcing a minimum off-time before allowing the compressor to restart, protecting it from damage.

Question 3

On a wiring diagram, a dashed line connecting two components typically indicates:

Accepted Answer

A mechanical linkage or enclosed assembly boundary

Answer

Dashed lines on wiring diagrams typically represent mechanical linkages between components or indicate that components are housed within the same enclosure.

Question 4

Which control component in a residential AC system senses indoor temperature and signals the system to cycle on or off?

Accepted Answer

Thermostat

Answer

The thermostat senses indoor ambient temperature and sends a low-voltage signal to the control circuit to energize or de-energize the system.

Question 5

A dual-voltage motor wired for 240V operation will have its internal windings connected in:

Accepted Answer

Series

Answer

For 240V operation, the windings of a dual-voltage motor are connected in series, while for 120V they are connected in parallel.

(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test

(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test

313D Electrical Schematics and Controls 2