Air Circuit Breaker
Air circuit breakers are used to interrupt circuits while current flows through them. Compressed air is used to quench the arc when the connection is broken.
Batteries
Batteries are used in the substation control house as a backup to power the control systems in case of a power blackout.
Bus Support Insulators
Bus support insulators are porcelain or fiberglass insulators that serve to isolate the bus bar switches and other support structures and to prevent leakage current from flowing through the structure or to ground. These insulators are similar in function to other insulators used in substations and transmission poles and towers.
Capacitor Bank
Capacitors are used to control the level of the voltage supplied to the customer by reducing or eliminating the voltage drop in the system caused by inductive reactive loads.
Circuit Switchers
Circuit switchers provide equipment protection for transformers, lines, cables, and capacitor banks. They also are used to energize and deenergize capacitor banks and other circuits.
Concrete Foundations
Concrete foundations or pads are laid for all large equipment, support structures, and control buildings in a substation.
Conduits
Concrete foundations or pads are laid for all large equipment, support structures, and control buildings in a substation.
Control House
The substation control house contains switchboard panels, batteries, battery chargers, supervisory control, power-line carrier, meters, and relays. The control house provides all weather protection and security for the control equipment. It is also called a doghouse.
Control Panels
Control panels contain meters, control switches and recorders located in the control building, also called a doghouse. These are used to control the substation equipment, to send power from one circuit to another or to open or to shut down circuits when needed.
Control Wires
Control wires are installed connecting the control house control panels to all the equipment in the substation. A typical substation control house contains several thousand feet of conduit and miles of control wire.
Converter Stations
Converter stations are located at the terminals of a DC transmission line. Converter stations can change alternating current into direct current or change direct current to alternating current. Sometimes converter stations are located at a generation power plant or at transmission substations. Two unsynchronized AC transmission systems can be connected together with converter stations.
Converter stations are also found in most substations for converting the emergency battery back-up system to AC power for use in an emergency.
Coupling Capacitors
Coupling capacitors are used to transmit communication signals to transmission lines. Some are used to measure the voltage in transmission lines. In signal transmission the coupling capacitor is part of a power line carrier circuit as shown in the schematic below. A coupling capacitor is used in this circuit in conjunction with a line trap. Line traps can be installed at the substation or on a transmission line tower.