03-10-2012, 01:15 PM
PROTECTION
PROTECTION.ppt (Size: 1.32 MB / Downloads: 318)
Accountability and Reliability:
Accountability and Reliability of Power Generated, Transmitted and Distributed plays an important role in the field of power system while supplying power to all corner consumers.
Accountability:
Measuring of Power at all levels to know the quantum of Generation, Energy transmitted and consumed.
Magnitude of energy at Generation and Transmission level is high and cannot be measured directly.
Reliability:
Some times the EHT/HT Lines / Transformers are disturbed due to faults.
This will cause disturbance in power system and there is a chance of collapse of the system if the fault is not cleared.
Hence proper protection system is a must.
Protection system:
Protective relaying system detects such abnormal conditions in the system and gives trip command to the respective breakers to isolate faulty lines.
The main inputs to the relays are Current, Current and Voltage, Breaker and Isolator status, input of all transformer mounted protection devices.
These inputs are to be given as per the requirements.
Discrimination of protection:
The protection scheme to be adopted is to be such that, it has to isolate only the faulty section.
Fault at F is far from the source and there are number of supply points in between, due to this fault relays provided at all the points will sense the fault causing tripping of healthy lines.
Directional Relay:
In the relay there will be one Voltage coil and One current coil and a disc in between the two coil cores.
Due to current in the coils, flux will be induced, and the flux induced in the voltage coil will lag the voltage by 90deg and the flux induced in current coil will be in phase with current
Due to these two fluxes Torque (T) will be produced and is proportional to these two fluxes and sin of the angle between them
Battery set charging:
Filling of electrolyte to all the cells as per supplier recommendations.
Allow the cells to stand for 8-12Hrs.
Record SG and Voltage of each cell.
Start initial charging at the rate of 6% AH of current.
Hourly readings of SG and voltage are to be recorded while charging
Charge the cells for a minimum time of 50Hrs,till the SG & Voltage are constant for 3 consecutive hrs.