Azamgarh 400KV Substation

ACP

For transferring of electrical power from generating unit to distributing units various types of electrical equipment are required. The main equipment required for the substation installations is explained below in details:nnLightning ArresternPower TransformernCTnCVTnBusbarnWave TrapnIsolatornCircuit breakernnLightning ArrestornnLightning Arrestor is the first member of the electrical substations. It protects the substation equipment from transient high voltage and also limits the duration and amplitude of the flow of current. The Lightning arrestor is connected between line and earth, i.e., in parallel with the equipment under protection at the substation.The lightning arrester diverts, the current of the surges to the earth and hence protects the insulation and conductor of the system from damage. The lightning arresters are several types and they are classified on the basis of the duties they perform.nnPower TransformernnPower transformers are used for stepping up the voltage for transmission at generating station and for stepping down the voltage for further distribution at main step-down transformer substations. Usually naturally cooled, oil immersed type two winding, three phase transformers, are used for rating up to 10 MVA. The transformer for rating more than 10 MVA, are usually air blast cooled. For very high rating, the force oil, water cooling and air blast cooling may be used.nnSuch type of transformer operated at full load, and it is disconnected at light load hours. The power transformers are arranged in banks and can be thrown in parallel with other units. Thus, the efficiency of the power transformer is maximum at full load (i.e., with iron loss to full load copper loss ratio 1:1).nnCurrent Transformern– A current transformer is a device for the transformation of current from a higher value to a lower value. It is used in parallel with AC instruments, meters or control apparatus so that the meter or instrument coil cannot conveniently be made of sufficient current carrying capacity.nCapacitive voltage transformer –  A voltage transformer may be defined as an instrument transformer for the transformation of voltage from a higher value to the lower value.nnBus-BarnnIt is one of the most important elements in an electrical power substation. It is a type of conductor carrying an electrical current to which many connections are made. In order words, bus-bar is a type of electrical junction in which the incoming and outgoing of electrical current take place.nnWhen the fault occurs in the bus- bar, then all the circuit equipment connected to that section must be tripped out to give complete isolation in the shortest possible time e.g. (60ms) so that the damage is avoided to the installation due to heating of conductors.nnWave TrapnnIt is placed on incoming lines for trapping the high-frequency wave. The high-frequency wave which is coming from the remote substation disturbs the waves of voltage and current. Wave trapper trips the high-frequency wave and diverts them to the telecom panel.nnIsolatornnIt is a type of switches which is employed only for isolating the circuit when the current has only been interrupted. The isolator is called disconnected switches operates under no load condition. They are not equipped with arc-quenching devices. They do not have any specified current breaking capacity or current making capacity. In some cases, it is used for breaking the charging current of the transmission line.nnCircuit BreakernnThe circuit breaker is a type of electrical switches which is used for opening or closing of electrical circuit whenever faults occur in the system. It consists of two moving contacts which are normally closed. Whenever the fault occurs in the system, the relay sends the tripping command to the circuit breaker and hence their contacts are moved apart.

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