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Generation
Electricity is produced in generators. Generators require other sources of energy. SCE uses more kinds of energy to produce electricity than any other utility in the world These resources include natural gas, a fossil fuel; falling water in hydroelectric plants; nuclear energy and renewable resources, like solar and wind. The primary energy source is burned as fuel or used directly to spin a turbine, which spins the generator. The generator is basically an electric conductor, such as copper, that spins within a magnetic field, producing “alternating current” electricity at 60 Hertz, or cycles per second.
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"Step-Up" Transformer
The electricity travels to a transformer, where its initial voltage, or pressure, is increased from about 13 kilovolts to 220 or 500 kilovolts.
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Transmission
The electricity flows onto transmission lines. These are large lines on metal frame towers. They are often compared to freeways because they transfer huge amounts of electricity over long distances.
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Transmission to Sub-Transmission Substation
At a transmission substation the power on the largest lines is divided among other transmission or sub-transmission lines of equal or smaller voltage and sent off to other locations. Substations include transformers, switches and capacitors, which help maintain voltage and efficiency of operation.
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Sub-Transmission
Power voltage is reduced in a transformer. Transmission voltages of 220 kv to 500 kv are generally reduced to a “sub-transmission” voltage of 66 kv.Sub-transmission lines carry power at 66 kv on taller wooden or metal poles.
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Sub-Transmission to Distribution Substation
They bring electricity to distribution substations, where the voltage is reduced again to distribution voltages. Distribution voltages are 16 kilovolts, 12 kilovolts or 4 kilovolts. These substations also include transformers, capacitors and switches.
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Apparatus
Transformer: A transformer increases or reduces voltage on a circuit. On the SCE system, voltage is increased only once, between the generating unit and the transmission system. At other points, transformers reduce the voltage for distribution to other circuits and for final delivery to customers.
Capacitors: A capacitor helps improve the efficiency of the flow of electricity by reducing energy losses at various points of the transmission and distribution systems. Capacitors are installed in substations and on utility poles.
Circuit Breakers: Circuit breakers on electricity circuits help direct the flow of electricity. If there is a power outage, the breakers on the system can be closed or opened to re-route electricity flow and restore power to as many customers as possible as soon as possible.
Fuses: Fuses on electric circuits serve the same purpose as fuses on customer electric equipment and appliances. They prevent overloading by interrupting electricity flow in the presence of more electricity than the system can safely handle. Fuses prevent overheating and fire.
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Distribution Lines to Distribution Substation
Distribution lines bring power to your neighborhood, either overhead or underground. On the distribution system, transformers on poles (pole-top), on a concrete pad at ground level (padmount) or underground (BURD, or buried underground residential distribution) reduce distribution voltages for distribution to residential neighborhoods. Capacitors, switches and fuses are also found along the distribution system.
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Meter
A “service” is the line that connects our distribution to the customer. The service directs electricity through the meter and the customer’s connection and fuse boxes. Typically, a household receives electricity at 240 volts (a kilovolt is 1,000 volts).
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Customer Location
The customer’s lights, appliances and other equipment put electricity to work. The work over time is measured in kilowatt-hours, which form the basis for usage measurement and billing. |
