Electricity

Question 1

What is Electromagnetism?

Answer 1

The force that causes the interaction between electronically charged particles

Question 2

What is the difference between direct current and alternating current? Give an example of both

Answer 2

For direct current, the voltage is always constant and flows in one direction.

Alternating current, the voltage switches between positive and negative, and the direction of flow occasionally changes

DC Example: Batteries and Solar Cells

AC Example: Travels through wire feeds

Question 3

Why would we use AC over DC?

Answer 3

Alternating current is more flexible being able to step up/down in voltage. DC can not do that since the voltage is constant. The voltage can go both from low to high and high to low.

AC also can travel longer distances

Question 4

Name some disadvantages of AC

Answer 4

Can lead to low “power factors” aka it isn’t as electrically efficient

Example: Lights flickering

Question 5

What phases is AC typically supplied in?

Answer 5

AC current is typically supplied in Single Phase or Three Phases

Question 6

Why would we have three phases instead of one phase?

Answer 6

Three phases has supplies more power than one phase to a circuit

Question 7

List some uses for single phase AC

Answer 7

Single Phase
- Lighting
- Small equipemnt
- (Smaller power requirements)

Question 8

What are the two main ways to cool down a transformer

Answer 8

Oil cooled
Dry/Air cooled

Question 9

What is the machine that distributes eletricity to various locations across the building?

Answer 9

Electrical Panels/Distribution Panels/ Switches
- separates out individual circuits
[ALSO HAS ACCESS TO CIRCUIT/FUSE BREAKER]

Example: 600 amps come into one switch in a building
- 200 amps directed to elevators
- 200 amps to meeting rooms
- 200 amps to kitchen

Question 10

What is an electrical riser?

Answer 10

A devise/mechanism to supply power to a vertical state and bring it to a new location.

Question 11

What are the three features that an electrical panel must have per city code?

Answer 11

1. Lock
2. Enclosed in a small, dry room or closet
3. Self-closing doors
   [Also should be labeled so users know where the circuits are in the building]

Question 12

For safety reasons what must each circuit have?

Answer 12

Each circuit has it’s own fuse of circuit breaker

Question 13

What are the similarities and differences between fuse and circuit breakers?

Answer 13

They are both used to control/prevent too much electrical flow through a circuit.

They are different as circuit breakers can be reset and reused. In contrast, a fuse must be replaced after the fuse has blown out. Also circuit breakers protect against overloading and short-circuiting while fuses only protect against overloading.

Question 14

What is a ground fault circuit interrupter [GFCI/GFI] and what is its purpose?

Answer 14

What we call an “outlet” the little red and black buttons with test and reset.

[Mainly for safety]
-Minimize risk of electrocution
-Designed to trip when it senses an imbalance in electrical flow
- It sees that power is not flowing from the active outlet to the ground
- It trips before the circuit is overloaded (in less than a second)

Question 15

What are the two meters used to calculate your electricity bill?

Answer 15

Consumed Energy and Demand

-Consumed Energy: Literally, the amount used
-Demand: Highest usage during the billing cycle (15-30mins)