BS: Lesson 6 - Electrical Systems Flashcards
Define volts in electricity and how it is measured.
Volts is the potential, or height, pressure, of electricity.
It is measured in volts.
Define electrical current and how it is measured?
Using the water analogy, curren is the “rate of flow” of electricity.
It is measured in amps.
How is resistance in electricity measured?
ohms
What is ohms Law
current = volts / resistance
Advantages of direct current (DC)
low voltage is less dangerous because it results in less current
What is P = V * I
general equation for DC
power = volts x current
How can the flow of electricity be reversed?
By reversing the voltage
Frequency
number of cycles per second
Power failure, PF
the lag in the current flow due to reversal of the voltage expressed as a ratio.
Which is greater, apparent power or real power, and why?
apparent power
Which draws more current, a load with a low power factor or a high power factore?
low power factor
Energy = _______ x ________
Energy = power x time
What is the difference between power and energy?
Power is the rate at which energy is used.
Energy is the technical term for work (the product of work and time).
What are the two forms of power generation and how do they vary?
Single-phase and three-phase
Single phase:
- most basic formsof power generation
- resulting power is AC
- used for mostly lighting and heating and large electric motors
Three-phase:
- a type of poly-phase system
- most common method used by girds to power up
- more economical becuase it uses less conductor material
What is a device that changes the voltage of an AC circuit to a hgher or lowerv value.
transformar
