SWITCH-GEAR


It deals with a wide range consumed with switching & protection a\system equipment normal, abnormal & short circuit conditions.


WHAT IS FAULT?:-


It in a defect in its circuit due to the current is diverted flowing the ground path.

Type of fault:-


  • Open circuit fault(series fault)
  • Short circuit fault(shunt fault)


Short circuit fault are two types  ---- 1) Unbalanced or Unsymmetrical fault , 2) Symmetrical fault

1) Unbalanced or Unsymmetrical fault:-

a) L - G (most common  70%)

b) L - L (15%)

2) Symmetrical fault :-

a) L-L-L

b) L-L-L-G

c) L-L-G(10%)

EFFECTS OF FAULT:-


-Current, voltages are unbalanced.

-Frequency is reduced.

-Temperature increases.

-Reversal of power flow.

-Unstability.

To overcome the faults, equipment are protected by some device called protective device.

-Main protective device are----

  1. Fuses
  2. Circuit Breaker
  3. Relay