PDX_21_Electrical Vocabulary Flashcards
The standard measurement of power, equivalent to one joule per second
Watt
Electrically charged atom or group of atoms
Ion
1000 W
Kilowatt
A measure of power equal to 746 W
Horsepower
A conductor, flow of energy, and electric potential difference (voltage), and some type of medium that creates resistance to flow
Circuit
The building block to energy. It states that current is directly proportional to voltage and indirectly proportional to resistance. If voltage goes up, current goes up. If voltage goes down, current will go down
OHM’s law
Measured and amps, it’s the amount of flow through a circuit
Current (I)
Measured in volts, the amount of force or potential in a circuit
Voltage (V)
Measured in ohms, the amount that slows down the current
Resistance (R/Ω)
The rate of energy transfer, expressed his energy/time (in hours)
Power (P)
When one column of charge passes a point in one second
Amp
Current that flows in one direction with constant voltage (example: batteries)
Typical for low-voltage applications which are less dangerous as there is less current.
DC current
Direction of the flow can be reversed rapidly by reversing the voltage resulting in a sine wave one plotted. The standard form of electrical current supplied by the utility grade and by most fuel powered generators.
AC current
Distribution of AC power using a system in which all the voltages of the sully vary in unison, when used when loads are mostly lighting and heating with a few large electric motors
Single phase electric power
Like an AC current but three different circuits each 120° out of phase with the other and one neutral current
Three phase AC current
The resistance in and alternating current, measured in ohms
Impedance
The face difference between voltage and current in AC circuits.
A.k.a. cosine of the angle between the voltage wave and resultant current wave, ranges from 0 to 1 and expressed as a percentage.
Power factor (PF)
The ratio between the average and maximum power demands of the building
Load factor
Part of the electrical resistance in an alternating current circuit caused by inductance and capacitance
Reactance
A machine that converts electrical energy into mechanical energy
Motor
In machine that converts mechanical energy into electrical energy
Generator
Generator that commonly produces AC current by converting mechanical energy
Alternator
Device that transfers energy from one circuit to another bye-bye not a couple and with no moving parts. It changes the voltage (or force) of an AC circuit to a higher or lower value
Transformer
The unit used for the apparent power in an electrical circuit, only useful in the context of AC circuits.
Volt-Ampere (VA)
A rating for transformers equal to the product of volts and amperes divided by 1000. The product of the kVA in the power factor gives the power in kilowatts.
KVA
Ratio of maximum demand or expected power usage to the total connected load
Demand factor
R1+R2+R3…
Series resistance (R total)
1/R1+1/R2+1/R3…
Parallel resistance (1/Rtotal)
Voltage (V) / Resistance (RΩ)
Ohm’s law: Current (I)
I x V
DC circuit power (watts) W
I x V x PF
AC circuit power (watts) W
I x V x PF x √3
AC 3 phase power (watts) W
Power (W) x time (T)
Energy in the system (watt hour)
Units for electricity are
Watts per square foot
Equivalent to one joule per second
Watt
A measure of the rate at which energy flows
Power
The “miles per hour” measurement of an electrical circuit
Watts
1 W =____ BTU
1 W = 3.412 BTU
High-voltage circuit is over this amount of AC power or this amount of DC power
Over 1000 V AC
Over 1500 V DC
Low-voltage circuits are between this range of AC or DC
50-1000 V AC power
120-1500 V DC power
High-voltage:
Electrical energy at voltages high enough to inflict harm or death upon living things.
Used an electrical power distribution, cathode ray tubes, to generate x-rays, and other scientific applications.
The amplitude of the wave represents the
Voltage
The distance between peaks of amplitude is
One cycle
Change the voltage (force) of and AC current to a higher or lower value. Separate wires are wound around an iron core. More winds = higher voltage.
Transformer
Transformers must be placed outside of the building or within a fire proof vault due to:
Humming noise, toxic fluids, and ventilation requirements.
Voltage is stepped up in order to
Transmit over longer distances without excessive losses.
It’s steps down to household levels at arrival.
Transformers have two windings, being the primary and secondary winding. Which do each do?
The primary winding is the coil that draws power from the source.
The secondary winding is the coil that delivers the energy at the transformed voltage to the load.
There are two types of secondary:
Two wire secondary,
And three wire secondary.
They produce:
Two wire produces 120 V with one hot.
Three wire produces 240 V with two hotlines.
A three-phase transformer means:
There are multiple leads on the secondary windings.
There are also different configurations, Wye and Delta.
Most common power system for residential and small buildings
120 ball/240 V single phase (one transformer), three wire system
Typical 240V loads include
Air conditioning/electric heating systems.
Electric dryers/electric water heater’s.
Large appliances (microwaves and stoves).
208/480 V three-phase (three transformer) system:
Three circuits carry three alternating currents which reach their instantaneous peak values at…
Different times.
Has an effective getting constant power transfer over each cycle of the current makes it possible to produce a rotating magnetic field in an electric motor.
The difference between single phase and three phase:
Single phase power is 60 cps (called hertz).
Three-phase power is 60 cps, but in three phases separated in time. Each phase is 1/3 cycles apart.
Like why a V 12 is more powerful
The numbers you typically see example 120/240 V or 120/208V change because
Single or three phase service.
But why? The numbers change when a wye connection is used.
Higher voltage allows for a larger number of fixtures to be on the search single circuit without an increase in
Current.
Circuit breakers come in the sizes:
10 A, 15 A, 20 A, 30 A
To calculate the electrical load, add the watt loads, divide by the results of the circuit and you are left with
The amps for that circuit.
Outdoor and indoor spaces must always be on different
Circuits
Demand charge:
Maximum power demand
x Demand tariff
Demand charged based on the highest message demand or percentage of, over the previous year
Ratchet clause
A unit of natural gas is:
A therm and is equal to 100,000 BTU
Gas is typically less expensive the more
It’s used
Gas and oil generators produce__megawatts
10-1000 MW
Found most in Midwest and Texas
Call plants generate__megawatts
20-3000 MW
Coal plants are found mostly in the East Coast
1 MW equals how many watts
1 million
Hydroelectric plants typically produce _ megawatts
6500 MW
Half the cost of other systems, and found in the Northwest
Photovoltaic panels produce___watts per panel
200 W per panel, not much
Tilt Angle of the PV array, to capture maximum insulation, should be equal to
The site latitude +15°
Today’s commercial to P the arrays have a maximum insulation to electric energy conversion rate of
12%
Hey PP system battery is generally expected to supply all of the new installations electrical requirements for a period of_days of cloudy weather
Three days of cloudy weather
