Electrical Flashcards
(14 cards)
What is Ohm’s Law?
E = I x R (Voltage = Amps x Resistance)
How do you calculate minimum circuit ampacity (MCA)?
MCA = (Largest Motor x 1.25) + All Other Loads
What is the full load amperage (FLA)?
The current a motor draws under full load conditions
What is the locked rotor amperage (LRA)?
The current a motor draws when starting (initial surge)
What color wire is typically used for the cooling circuit?
Yellow (Y)
What does a capacitor do in an HVAC system?
Stores and releases electrical energy to start motors
What is a contactor used for?
It connects and disconnects electrical power to the compressor or fan motor
What size breaker is required for a 5-ton unit?
Typically 30-40 amps (check equipment label)
How do you test a capacitor?
With a multimeter on microfarad (µF) setting
What does ECM stand for in motors?
Electronically Commutated Motor.
What is the most common voltage for residential HVAC systems?
240V
What is a common control voltage in HVAC?
24V
What type of fuse is used for HVAC systems?
Time-delay (dual element) fuses.
What does a relay do?
Controls a high voltage circuit using a low voltage signal.
