Low Voltage
What circuit is the low-voltage power supply, typically 24V?
The R circuit
What does the letter R represent?
resistance
Which winding is considered the input winding?
What is the primary function of a run capacitor in an HVAC system?
To provide a continuous voltage phase shift to the motor windings
What kind of switch is manually operated to completely disconnect power from the HVAC unit?
Disconnect switch
The Y circuit
What does the letter E represent?
voltage or electromotive force
What's the term used to identify how the electricity moves from one winding to the other?
induction
True/False: AC motor capacitors are polarity sensitive.
False (AC motor capacitors are non-polarized)
A switch in a 120V circuit is closed. What will the voltage reading across the switch be?
0V
What is the circuit that energizes the indoor fan only?
The G circuit
What does the letter I represent?
current, intensity, or electron flow
What determines how much power is picked up by the secondary winding?
the number of turns in the winding
A dual run capacitor is used to operate __________.
A fan motor and a compressor motor
What pulls the contacts open on a normally closed relay?
electromagnet
What is the circuit that energizes the heat in a gas furnace or electric furnace
The W circuit
What type of load does Ohm's law not apply to?
Inductive loads
To find the current any transformer can sustain, divide the _______ rating by the designed ______.
VA, secondary voltage
What does the "uf" or "μF" on a capacitor label represent?
Microfarads
Are pressure switches normally open or normally closed?
normally closed
What is the circuit that energizes the reversing valve on a heat pump?
The O/B circuit
In a 240V circuit containing 60Ω, the current flow is ________?
4A
A 24V transformer has a rating of 2A. What is its VA rating?
48VA (V x A) (24Vx2A=48)
What will happen if a run capacitor is too small for the motor or is weak?
The motor will run hotter and less efficiently, pull higher amps.
Are thermostats switches normally open or normally closed switches?