Electricty Flashcards
What do contactors have?
Coil
Contacts and mechanical linkage
Contactors are used on
Residential Ac and heat pumps
Solenoid flow control flow
Gas, water and refrigerant
What is potential difference
Measures in volts
Voltmeters measure
Potential difference between two specific points
In A/C
120V (Hot Black)
240V (Black and red or blue)
Ground is always bare wire or green
Quantity and intensity
of electrons moving through a conductor
Is amperage
Coils increase what?
Accuracy of ammeter
Reactance is what?
Resistance when current is flowing
In inductive reactance, the magnetic Fidel’s forms with current flow
And so field from one coil affects the next
Draw Capacitive Reactance Symbol
Current Always leads voltage by
90
Impedance is what?
Sum of all types of resistance
746 watts
1 HP
Three phase circuits
Each loop 120 degrees apart
Polarity changes 7200
Conductors have 3 or less
Electrons
Insulators are
Materials with 5 or more electrons
Circuit breakers
Considered as time delayed devices
Switches are wired
In series with load
Transformers have two windings which are?
Primary(incoming voltage)
Secondary(outgoing voltage)
Solenoid valves (electrically operated)
What type of thing?
Electromagnet coil lift plunger to open or close the valve
It is induction
What are relays
Electromagnetism to operate switch and contacts
Contactors are control heavier loads and are
Normally open or close
Slippage is the difference
Between calculated and real speed
Split Phase Motor
Has run and start
Start Winding determine direction of directions
-disconnects 75% of the rated RPM
Symbols for contactors
Are shown de-energized (no power)
Normally open
Contactors have what elements
Coil, contacts, mechanical linkage
Contactors start when
Coil is energize
Contractors are mostly used in residential AC and what
Heat pumps
What is the first step in troubleshooting a contractor?
Chocolate popper voltage
You can also check the mechanical linkage
Motors are inductive
Heaters are resistive don’t like the number 
Current relays are only used on six metering devices so the pressures equalize is equal
Compressor is off and starting is easier under low head pressure
A start capacitor adds what to the system
Starting twerk 
The heat bump is a reversible AC unit
AC mode it absorbs heat from the inside space injected to the outside and heat pump, mold, absorbs heat from the outside and then rejects it into the inside. Space
Heat pump reversing valve determines indoor outdoor coil function and control from the thermostat. What are the four pipe connections?
Discharge inlet and suction outlet and two outlets changed from indoor to outdoor coils
Draw the cooling and heating on the heat pump visually 
In cooling mode, the indoor coil absorbs heat, and the outdoor coil reject heat
In heating mode and the heat pump, the outdoor coil, absorbs heat, and the indoor coil rejects heat
