Electrical Power Distribution
The Power Plant
•Power plants consist of a ______electrical generator
•Generator can be made to spin by steam from burning coal, steam from a nuclear reactor, water from a hydroelectric dam, etc.
•Generates ______-phase AC power
Single-Phase AC (______)
•What is in your house
•Oscillating power = alternating current
•DC (direct current) is a steady stream of electrons flowing one direction. Ex: ______
Three-Phase Power
•What is produced at a ______
•Three Phases of AC Power offset 120 degrees from each other.
•Why three phases? At any given moment one of the three phases is nearing a peak so maximum power output.
Power Plant
•Four wires coming out of a power plant: three phases plus a ground
Which one do you think is the ground?
Transmission Substation
•Uses ______to step up the voltage
Ex: 12,000 volts out of the power plant is stepped up to 500,000 volts for transmission
•Why?
Increasing the voltage reduces ______when traveling long distances
•Average transmission distance is 300 miles
Power Substation
•Power coming off the transmission lines use transformers to stepped-______the voltage to less than 10,000 volts
•Distributes power in multiple directions.
•Can be disconnected from the transmission grid if necessary.
Distribution
•Power goes from the transformer to the “distribution bus”
•The distribution bus distributes power to two separate distribution lines at two different ______(standard line voltage ~7,200V and a higher voltage)
At your house…
•There is usually another transformer near your house stepping down the voltage even further.
•Only ______of the three original phases will enter your house.
•A typical house uses ______V for large appliances like electric stoves and air conditioning systems and ______V for standard plug in the wall items like TVs and toasters.
•The 240V enter your house through a ______-______meter
•This is how the power company charges you for usage.
Fuses and Circuit Breakers
•Power enters your house through a fuse and/or circuit breaker
•THESE ARE ______DEVICES
•For example if wire comes loose, a mouse chews through a wire, a motor overheats and melts, etc. a fuse will blow or a circuit will trip so power is cut off to avoid fires.
Review
Step 1: Electricity leaves Power Plant in ____ phases.
Step 2: Voltage is stepped up for transmission to
minimize ______.
Step 3: Voltage is stepped-down at the ______.
Step 4: Voltage is further stepped down and enters your
house at ____ Volts.