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The Substation

  1. Power Lines - High-voltage electricity enters the substation on two transmission lines near the top of the RED power poles. Electricity flows through the RED conduit lines to the ORANGE conduit lines and is delivered to the transformers.
  2. Circuit Breakers - Circuit breakers, in BLUE, are safety switches that automatically stop (or break) the electric current flowing through a power line. They are triggered during an emergency to protect workers and equipment.
  3. Power Switches - Power switches, in GREEN, are used to turn power off and on, like a light switch in a room. They can work in pairs to shut off the flow of electricity to the equipment between them. This lets technicians work safely in specific areas.
  4. Transformers - Transformers, in ORANGE, reduce the electric current from a high voltage to a lower voltage. At this substation, electricity enters the substation at 115,000 volts (115 kV) and is transformed to a lower voltage of 12,000 volts (12 kV).
  5. Distribution Lines - The lower-voltage current from the transformers exits the substation yard through several distribution lines, in YELLOW. These lines branch out and carry the low-voltage electricity to nearby neighborhoods in Topeka where it is used. 

What is a substation? What does it do?

A substation's main job is to transform electricity from high voltage to low voltage.

Electricity, which travels along transmission lines at high voltage, arrives at a substation and is transformed to a lower voltage. This low-voltage electricity then continues moving along power lines into your neighborhood until it reaches your home, school or business.

Why does electricity travel to a substation at a high voltage?

Power plants are often far away, so electricity is transported along transmission lines at a high voltage to deliver it more efficiently. High voltage is like high pressure in a water hose - pressure helps deliver greater quantities of electricity over long distances.

Why does electricity have to be transformed?

We can't use high-voltage electricity at home. Voltage is like pressure. High-voltage electricity has too much pressure to run our everyday things. It would be like trying to fill a glass of water with a fire hose!

What's the voltage in my home?

The electricity we use each day is at a lower voltage. In your home, the voltage you plug into is only 120 volts. The high voltage of a transmission line is at 115,000 volts or more - that's about 1,000 times as strong!

Monitoring and control equipment in the substation yard.

The substation at Education Station includes monitoring and control equipment located in small sheds along the back wall. This equipment measures and checks the electric current. Careful monitoring at this substation provides a safe connection to all other areas of the power grid network.

The Circuit Breaker

  • A. Normal Condition - Contacts are connected and will provide uninterrupted power flow.
  • B. Surge Protection - The circuit breaker detects a problem, separates the contacts and uses non-conductive gas to extinguish the resulting electrical arc.
  • C. Circuit Interrupted - Contacts remain separated to prevent the flow of electricity.  
  1. Control Box - Houses equipment to control operation of the circuit breaker.
  2. Electrical Bushing - Works as an insulator around the energized cable.
  3. Non-conductive Gas - Prevents electricity from arcing across separated contacts.
  4. Contacts - When connected, contacts provide a path for electricity.
  5. Circuit Breaker Gas Tank - A metal tank to hold the non-conductive gas.

What does a circuit breaker do?

Circuit breakers can automatically stop electric current.

Circuit breakers can break the flow of electricity through a power line. They are important for protecting workers and equipment during an emergency.

What happens inside?

Each circuit breaker includes three tanks. Inside each tank, two contact points are ready to separate and break the current if there is an unexpected power surge, like from a lightning strike. This turns power off and protects people and equipment from harm.

The Power Switch

  1. Closed Connection - Contacts are connected so that power can flow through the switch.
  2. Open Connection - Power cannot flow; contacts are separated.
  3. Electrical Insulator - Keeps the electricity away from the support stand.
  4. Contacts - When contacts (the metal plates on top of each electrical insulator) are touching, electricity can flow through from one side of the switch to the other.
  5. Switch Handle - Rotating the handle turns gears that move the contacts at the top of the switch away from each other. This breaks the path of electricity.

What does a power switch do?

A power switch can control the flow of electricity.

A switch controls an electric circuit and, like a light switch in a room, turns power off and on.

Why do substations have power switches?

Technicians can open and close switches to break the flow of electricity in a line. Switches can be used in pairs to turn power off to the equipment between them. This lets technicians work safely in that area of the substation.

The Transformer

  1. High Voltage - 115,000 Volts.
  2. Low Voltage - 12,470 Volts.
  3. Oil Cooling Radiator - Oil absorbs the heat created by electric current.
  4. Electrical Bushing - Works as an insulator.
  5. Primary Coil - Coil with high-voltage current.
  6. Secondary Coil - Coil with low-voltage current.
  7. Cooling Fans - Helps cool oil and equipment.
  8. Iron Core - Inside center of the coils.
  9. Control Box - Monitors and controls operation of the transformer.

What does a transformer do?

A transformer changes the voltage of electricity.

At Education Station, Westar Energy's transformer converts electricity from 115,000 volts (115 kV) to 12,470 volts (12 kV).

What happens inside?

Two coils wrap around an iron core to produce a magnetic field. This helps transfer the electric current from one coil to the other to reduce the voltage and increase the current. This process produces a lot of heat, so the equipment is cooled by oil and cooling fans.

Where does the low-voltage electricity go?

Lower voltage electricity exits the Education Station transformers at 12,470 volts and travels to the distribution lines, which send power to neighborhoods all over Topeka.

What is voltage?

Voltage equals pressure, like the pressure of water in a hose. The more pressure in an electric line, the farther the electricity can flow.


Kanza Education and Science Park
I-70 & MacVicar Ave.
Topeka, KS 66606

The Education Station is open to the public 365 days a year. School field trips are always welcome.
Contact Larry Robbins with USD 501 at 785-295-3063 or by email.

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