29 June 2011

Various Substation Equipment

Various substation equipment employed in the substation are:

Substation Equipments:

Busbars: It acts as a nodal point in the substation. It connects the incoming circuits and outgoing circuits. Bus bars are solid conducting bars carrying high current and voltage

Power Transformer:In substation, transformers are employed to step up the voltage or step down the voltage. Power plant substation steps up the voltage on the other hand distribution substation steps down the voltage using power transformers.
Lightning Arrester: This discharges the surges generated due to lightning strikes and switching (in EHV) surges to the ground. Provides high impedance to earth for normal voltages and low impedance path to high frequency voltages to ground. This is possible with the help of non linear resistors.
Disconnecting switches or Isolators: To open and close the circuit. Isolators are operated only under no load.

Earth Switches: Earth switches connect the equipment to ground to discharge any capacitive charge present in the equipment (eg Busbar) to ground under no load condition , protects the working personnel from shocks.
Circuit breakers: Circuit breakers are the interrupting devices which opens the circuit during fault condition and isolates the fault.
Current Transformer: Current Transformers are meant for measuring the current ratings in the high voltage lines.
Potential Transformers: Potential Transformers are meant to measure the voltage in high voltage circuits.
Shunt Reactor: During low load conditions the shunt capacitance predominates. To compensate the shunt capacitance shunt reactance are employed in the large substations and will be switched on during low load conditions.
Shunt Capacitors: Shunt capacitors are used in substation for improving the power factor of the system. Shunt capacitors provide reactive power to improve the power factor.
Metering panel: Display the status of equipment and control purpose in substation control room.
Substation earthing system: Earthing is provided to protect the power system equipment and operating personnel from shocks when fault occurs. Grounding grid consists of conductors connected in the form of grid. All the power system equipments in substation are connected to the grid by conductors. Earth electrodes is also employed in substation for grounding purpose.

Wave trap or line trap:Traps the high frequency component signals in the power lines.
Cables: Different cables employed in substation constitutes Power Cables and Control Cables. 
Insulators:Current carrying components in the substation are insulated from the earth (flow of current to body of equipment) through the insulators.

Isolated phase bus duct system: For carrying high currents from generator to switch-yard transformers normal cables cannot be employed. In such cases Isolated phase bus duct is used. This constitutes copper bars or Aluminum bars for carrying the high currents.

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