What is Ground Fault and Earth fault:
Ground Fault is nothing but a fault or contact occurs between the Live conductor to ground/neutral point. In this fault the fault current directly flows to the ground. In this, The fault may be in one phase to ground (L-G) or one or more phase to ground (LLG) or LLLG. Ground Faults are more severe than Earth Faults due to the flow of large amount of current flow, which can damage various equipment of a power system if the fault is not cleared within a specified time.
Reason for Ground Fault:
- Insulation failure i.e loss dielectric property
- Physical damages in underground cable or water entering into the cable drench.
- Overload of the cable which results conductor may get cut and fall into the ground point.
- Natural disturbance such as falling tree in the conductor, water flow on the insulator, living things touches live wire and ground point.
How to Protect a system against Ground fault:
Some of the protective relays are used to trip the system under fault condition. The circuit quantity is measured by the instrument transformer such as Potential transformer and Current Transformer. The output of these transformers is given to the relays. The relay contains preset value, if the current or voltage exceeds the preset value then the relay operates the associated circuit breaker, then the fault will be cleared. Some relays are
- Current-based relays: Overcurrent relay, Instantaneous overcurrent relay, Earth fault relay etc.
- Voltage-based relays: Overvoltage relay, over fluxing relay, etc
In house hold, we can eliminate by RCCB (residual case circuit breaker) or ELCB (Earth leakage circuit breaker)
Earth fault is an Open Circuit fault; where the power carrying cable or conductor breaks and gets into contact with earth or a conductor capability material in contact with earth. System at load end in this case is disconnected form source in in case of radial power flow.