final Flashcards
(41 cards)
Electrons that are no longer bound to their atoms
what are free electrons
electric current that regularly reverses direction is called
alternating current
electric current is measured in
amps
electrical potential is
the ability to make current flow
In a basic electric circuit with a steady potential, when resistance increases
current decreases
In a series circuit, total resistance is determined by
adding the sum of all individual resistances
in a parallel circuit
the voltage stays the same throughout the circuit
What is the current draw of a 1,200 w operating on a 120 v AC power supply
1,200 w/ 120 v = 10 a
AC power can be converted to DC power through use of component called
rectifiers
most hvac systems operates on
alternating current
if a conductor is coiled as in a relay coil, then passing current through it will the magnetic field
intensify
what does a transformer do
increases or decreases incoming voltage
impendance is the combined effect of
resistance, inductive reactance, and capacitive reactance
a delta three phase power supply provides
240 v between the legs
what unit specification should be used to size the overcurrent protection
the maximum overcurrent protection (mocp)
what specification on the unit data plate should be used to size the power wire
the minimum circuit ampacity (mca)
the voltage between any let of a 480 v WYE transformer and ground is
277 v
the different color used for the color bands on resistors represent
numbers
when the 3rd color band is silver, it represents
the multiplier for the resistor
This component uses the properties of AC induction to step up of step down voltage for particular hvac applications
transformer
the primary winding of a 120 v transformer has 200 turns. the secondary winding has 20 turns. what is the secondary winding voltage
12 v
an electrical component that stores energy when an electric charge is forced onto its plates is called a
capacitor
compared to motor capcacitors, paper and film capacitors are
smaller in rating and physical size
what is the common sensing element used in as electronic thermostat
a thermistor
