HVAC REVISION Questions Questions Correctly
Answered and Updated!!!
(T or F) Single phase power can be obtained from a 3 phase system. - ANSWER TRUE.
Single phase obtained from 3 phase by using just 2 hot wires or 1 hot and a neutral.
Most residential units have 2 hot wires and a neutral wire:
What is the supplied voltage?
How many phases are supplied? - ANSWER 240V
Single phase
An advantage of Alternating Current is........ - ANSWER AC can be:
GENERATED at one voltage
transmitted at a HIGHER VOLTAGE
reduced to a lower voltage at the POINT OF USE
What is the Operating Principle for a transformer? - ANSWER Electrical energy can be
efficiently transferred from one winding to another by magnetic induction.
Does a Step-up transformer increase or decrease voltage? - ANSWER Increase voltage
What is Ampacity? - ANSWER The amount of current a wire can safely carry.
, Name the two devices that protect against over-current. - ANSWER Fuses and circuit
breakers
(T or F) A dual-element plug fuse should be used in circuits serving electric motors. -
ANSWER TRUE:
Time delay fuses are necessary when fusing a circuit with an electric motor.
What two ratings determine the physical size of a cartridge fuse? - ANSWER Amperage
and voltage ratings
GFCI protects people against a............. - ANSWER Potentially hazardous ground fault
Residential lighting and receptacles use....... - ANSWER 120V single phase
What are the two types of transformers? - ANSWER Step up or Step down
Step up transformers make it possible to _____ voltage.
Step down transformers make it possible to _____ voltage. - ANSWER Increase voltage
Decrease voltage
Transformers are _____% to _____% efficient. - ANSWER 96 - 98%
A transformer consists of........... - ANSWER two copper windings (coils) electrically
separated from each other. The coils are wound around a core of laminated soft iron
sheets.
Answered and Updated!!!
(T or F) Single phase power can be obtained from a 3 phase system. - ANSWER TRUE.
Single phase obtained from 3 phase by using just 2 hot wires or 1 hot and a neutral.
Most residential units have 2 hot wires and a neutral wire:
What is the supplied voltage?
How many phases are supplied? - ANSWER 240V
Single phase
An advantage of Alternating Current is........ - ANSWER AC can be:
GENERATED at one voltage
transmitted at a HIGHER VOLTAGE
reduced to a lower voltage at the POINT OF USE
What is the Operating Principle for a transformer? - ANSWER Electrical energy can be
efficiently transferred from one winding to another by magnetic induction.
Does a Step-up transformer increase or decrease voltage? - ANSWER Increase voltage
What is Ampacity? - ANSWER The amount of current a wire can safely carry.
, Name the two devices that protect against over-current. - ANSWER Fuses and circuit
breakers
(T or F) A dual-element plug fuse should be used in circuits serving electric motors. -
ANSWER TRUE:
Time delay fuses are necessary when fusing a circuit with an electric motor.
What two ratings determine the physical size of a cartridge fuse? - ANSWER Amperage
and voltage ratings
GFCI protects people against a............. - ANSWER Potentially hazardous ground fault
Residential lighting and receptacles use....... - ANSWER 120V single phase
What are the two types of transformers? - ANSWER Step up or Step down
Step up transformers make it possible to _____ voltage.
Step down transformers make it possible to _____ voltage. - ANSWER Increase voltage
Decrease voltage
Transformers are _____% to _____% efficient. - ANSWER 96 - 98%
A transformer consists of........... - ANSWER two copper windings (coils) electrically
separated from each other. The coils are wound around a core of laminated soft iron
sheets.
