Thursday, May 13, 2010
9,10/5/10
Protection main function:
1-safeguard the entire system to maintain continuity of supply.
2-minimize damage and repair costs
3-ensure safety of personnel
Protection-basic requirements:
1-Selectivity
2-Stability
3-Speed
4-Sensitivity
Protection basic components:
1-Voltage transformer and Current transformer
2-Fuses
3-Relays
4-Circuit breakers
5-DC batteries
1-safeguard the entire system to maintain continuity of supply.
2-minimize damage and repair costs
3-ensure safety of personnel
Protection-basic requirements:
1-Selectivity
2-Stability
3-Speed
4-Sensitivity
Protection basic components:
1-Voltage transformer and Current transformer
2-Fuses
3-Relays
4-Circuit breakers
5-DC batteries
6/5/10
Differential relay required at least a minimum v alue of current flowing through its operating winding for operation.
-They will only operate if the operating current exceeds a certain percentage of the restraint or bias current.
-This ensures the relays current required for operation is always greater than the out of balance current under maximum through fault condition.
The second bias or restraint incorporated into most transfomer differential relays is the bias to prevent relay operation against magnetizing in rush current on energizing the transormer.
-They will only operate if the operating current exceeds a certain percentage of the restraint or bias current.
-This ensures the relays current required for operation is always greater than the out of balance current under maximum through fault condition.
The second bias or restraint incorporated into most transfomer differential relays is the bias to prevent relay operation against magnetizing in rush current on energizing the transormer.
5/5/10
Relay usually installed with current transformer for current measurement.
-The Relay should not operate when the circuit is carrying the maximum load continuosly.
-When the equipment or circuit is allowed to overload in limited time -say by 30%bfor less than half an hour then the relay should be set not operate at the over loaded current in the slightly shorter than the maximum over load time.
-Under fault condition,the relay should operate and disconnect the circuit in the time before exceeding the short circuit rating of the protective equipment.
-Realys are normally classified into the time/current characteristics as:
*Instantaneous
*Definite-time
*Inverse definite Minimum Time(IDMT)
-The Relay should not operate when the circuit is carrying the maximum load continuosly.
-When the equipment or circuit is allowed to overload in limited time -say by 30%bfor less than half an hour then the relay should be set not operate at the over loaded current in the slightly shorter than the maximum over load time.
-Under fault condition,the relay should operate and disconnect the circuit in the time before exceeding the short circuit rating of the protective equipment.
-Realys are normally classified into the time/current characteristics as:
*Instantaneous
*Definite-time
*Inverse definite Minimum Time(IDMT)
4/5/10
-To meet protection objectives and requirements,protection systems are required where protective devices or gears are combined together ready to disconnect faulted equipment.
-Protective scheme on the other hand is a coordinated arrangement of several protective systems for protection of equipement bor power system.
-Current and voltagte transformers are the common devices used in protective system.
-Voltage transformer are used for measurement ,directional protection -conventional or reverse power relays -undervoltage/overvoltage protection.
-Two types of voltage transformer constrution in used:
*Electromagnetic type:primary and secondary winding are magnetically coupled via iron core.
*Capacitor voltage transformer -which is connected to main circuit with series of capacitors.
-Protective scheme on the other hand is a coordinated arrangement of several protective systems for protection of equipement bor power system.
-Current and voltagte transformers are the common devices used in protective system.
-Voltage transformer are used for measurement ,directional protection -conventional or reverse power relays -undervoltage/overvoltage protection.
-Two types of voltage transformer constrution in used:
*Electromagnetic type:primary and secondary winding are magnetically coupled via iron core.
*Capacitor voltage transformer -which is connected to main circuit with series of capacitors.
Monday, May 3, 2010
3/5/2010
Site Visit to Pencawang Protab Agrobase Packaging,Changlun
Vacuum Test Equipment(Green ~Acceptable,Red~defective);Voltage set at 25kv
Electrical Machinery
LV Distribution Board (pengagihan Bekalan)It also used to trace leakage of electricity,therefore tranduce analog to digital then send to SCADA
Remote Terminal Unit PE Telekom Jitra
Our main objective for today~~to trace out flash over.Needed to confirm whether circuit breakers in the good condition
setting up Vacuum Test
Circuit breakers (After flash over)
Maintenance of circuit breakers
Tracing out each line
Tracing the fault
Drawing out Schematic Diagram(to bring back Pencawang as reference)
Remote Terminal Unit PE Telekom Jitra
Our main objective for today~~to trace out flash over.Needed to confirm whether circuit breakers in the good condition
setting up Vacuum Test
Circuit breakers (After flash over)
Maintenance of circuit breakers
Tracing out each line
Tracing the fault
Drawing out Schematic Diagram(to bring back Pencawang as reference)Sunday, May 2, 2010
Subscribe to:
Posts (Atom)
