General Information
The City has 6 substations located throughout the city. The image above is one of the four transformers that provides electric power to the largest customer, Micron Technology. Although the transformer itself (located just in front of the wall) is a typical transformer that the City would use, the gear attached to the opposite end referred to as switchgear, is not found in any of the other facilities. Use the menu to the left to read more detailed information about the topics below.

Transformers
Transformers such as the one above tranform one elctric voltage into another. In this example the input voltage is 115,000 Volts and the output voltage is generally around 7,800 volts. Two of the stations in Manassas have 230,000 volt inputs.
The large stacked cylinder objects on top of the transformer (pictured left) are called insulators. They are required to keep the incoming electric lines far enough away from other metal surfaces that are grounded. If proper clearances are not maintained, there would be enough electrical potential for the electric to "jump" to the metal or grounded surface and cause a fault and a lot of damage.

Control House
The image to the left of a control house in a substation. If you read through and of the SCADA information pages, you will notice that the SCADA equipment, or RTU, is located in the last section to the right in the picture. The control house is the manual interface for the substation. A technician or lineman can control circuit breakers (open and close) or place them in different operating modes. In addition, it generally houses all of the protective gear for all of the electrical equipment.

 

Protection
The image to the left is an electronic processor based protective relay. These devices are responsible for ensuring the safety of personnel working on equipment and for the safety of the general public. If a tree falls on an energized line a device such as this one will trip the circuit breaker. Although it is actually much more sophisticated than that, you could compare it to a circuit breaker in a home. If you overload your electrical outlets in your house, a circuit breaker or fuse will blow in your electrical panel.