# Symmetrical Fault

## Symmetrical Fault:

Location of Reactors in Power System : Short circuit current limiting Location of Reactors in Power System may be con­nected in series with each generator in series with each feeder and in bus-bars. No definite statement can be given as to which one of the above locations is preferable; each installation has its own particular demands which must be carefully considered before a choice of Location of Reactors in Power System can be made. 1.Generator Reactors: When the reactors are connected in series with each generator, they are known as generator reactors (see Fig. 17.4). In this case, the reactor may be considered as a …

Percentage Reactance in Power System : The Percentage Reactance in Power System of generators, transformers, reactors etc. is usually expressed in percentage reactance to permit rapid short circuit calculations. The percentage reactance of a circuit is defined as under : It is the percentage of the total phase-voltage dropped in the circuit when full-load current is flowing. i.e., Where I = full-load current V = phase voltage X = reactance in ohms per phase Alternatively, percentage reactance (%X) can also be expressed in terms of kVA and kV as under : where X is the reactance in ohms. If X is the only reactance element in the circuit, then short-circuit current is …

Short Circuit kVA : Although the potential at the point of fault is zero, it is a normal practice to express the short-circuit current in terms of Short Circuit kVA based on the normal system voltage at the point of fault. The product of normal system voltage and short-circuit current at the point of fault expressed in kVA is known as Short Circuit kVA. Let V = normal phase voltage in volts I = full-load current in amperes at base kVA %X = percentage reactance of the system on base kVA upto the fault point Short-circuit kVA for 3-phase circuit i.e. Short Circuit kVA is obtained by multiplying the …

Symmetrical Faults on 3 Phase System : Most of the Symmetrical Faults on 3 Phase System on the power system lead to a short-circuit condition. When such a condition occurs, a heavy current (called short circuit current) flows through the equipment, causing considerable damage to the equipment and interruption of service to the consumers. There is probably no other subject of greater importance to an electrical engineer than the question of determination of short circuit currents under fault conditions. The choice of apparatus and the design and arrangement of practically every equipment in the power system depends upon short-circuit current considerations. That fault …