CLICK HERE TO DOWNLOAD PPT ON GENERATOR PROTECTION
Generator Protection Presentation Transcript
1.STATOR END WINDING ASSEMBLY
2.ROTOR SLOT
3.ROTOR VENTILATION
4.ROTOR BODY WITH CROSS-POLE SLOTS
5.500 MW TG ON TEST BED
6.AIR-COOLED TURBOGENERATOR GENERAL VIEW
7.REMOVAL OF SLIP RING FAN FROM OUTER C.C BOLT TOP INSULATION
8.Nature of faults in generator
Insulation failure.
Tends to deteriate with rising temp.
Insulation failure may cause inter-turn fault, ph to ph or earth fault.
Bring winding in to direct contact with core plates.
Any failure to restrict earth fault may result into core plate damage.
Insulation of rotor winding is also important.
Insulation failure.
Tends to deteriate with rising temp.
Insulation failure may cause inter-turn fault, ph to ph or earth fault.
Bring winding in to direct contact with core plates.
Any failure to restrict earth fault may result into core plate damage.
Insulation of rotor winding is also important.
9.Function of relays
Relay can not prevent faults but can detect and minimize fault damages.
Relay can not prevent faults but can detect and minimize fault damages.
10. Protection applied to generator
Relays to detect faults outside generator
Relays to detect faults in side generator
Lightening arrestors.
Over speed protections.
Oil flow device.
Temp measuring device for bearings, stator winding, transformer windings, Oil temp.
Relays to detect faults outside generator
Relays to detect faults in side generator
Lightening arrestors.
Over speed protections.
Oil flow device.
Temp measuring device for bearings, stator winding, transformer windings, Oil temp.
11. Generator earthing
12. GENERATOR BACKUP PROTECTION
The purpose of the generator backup protection is to disconnect the generator from the bus-bars, if a system fault has not been cleared by the main protection after a predetermined time delay has elapsed. There are two types of backup relays available to perform this function. A voltage dependent overcurrent relay and a impedence relay.
The purpose of the generator backup protection is to disconnect the generator from the bus-bars, if a system fault has not been cleared by the main protection after a predetermined time delay has elapsed. There are two types of backup relays available to perform this function. A voltage dependent overcurrent relay and a impedence relay.
13. REVERSE POWER PROTECTION
Failure of the prime mover of a generator set ,will keep the set running as a synchronous compensator, taking the necessary active power from the net work and could be detrimental to to the safety of the set, if maintained for any length of time. The amount of power taken will depend on the type of prime mover involved. It ranges from 5% to 25%.
Failure of the prime mover of a generator set ,will keep the set running as a synchronous compensator, taking the necessary active power from the net work and could be detrimental to to the safety of the set, if maintained for any length of time. The amount of power taken will depend on the type of prime mover involved. It ranges from 5% to 25%.
14. Negative phase sequence protection
While balanced load conditions produce balanced currents which are equal in magnitude and displaced by 120 degrees and the field which they create rotates at synchronous speed with the motor and no eddy currents are induced. however when the load is unbalanced, negative phase sequence currents are produced which are also in magnitude and displaced by 120 degree but rotates in the opposite direction at twice the synchronous speed. These double frequency eddy currents induced in the rotor of the machine may cause excessive heating, mainly in the surface of the cylindrical rotor.
While balanced load conditions produce balanced currents which are equal in magnitude and displaced by 120 degrees and the field which they create rotates at synchronous speed with the motor and no eddy currents are induced. however when the load is unbalanced, negative phase sequence currents are produced which are also in magnitude and displaced by 120 degree but rotates in the opposite direction at twice the synchronous speed. These double frequency eddy currents induced in the rotor of the machine may cause excessive heating, mainly in the surface of the cylindrical rotor.
15. Field failure protection
Loss of generator field excitation under normal running conditions may arise due to any of the following condition.
1. Failure of brush gear.
2.unintentional opening of the field circuit breaker.
3. Failure of AVR.
When generator on load loses it’s excitation , it starts to operate as an induction generator, running above synchronous speed. cylindrical rotor generators are not suited to such operation , because they do not have damper windings able to carry the induced currents, consequently this type of rotor will overheat rather quickly.
16.Over-voltage protection
The field excitation system of generators is usually arranged so that over voltage conditions at normal speeds possibly can not occur.the conditions where over-voltage , other than transient over-voltage, do occur is when the prime mover speed increases due to sudden loss of load.the control governors of industrial prime movers are inherently very sensitive to speed changes and the resulting increase from any sudden loss of load is normally checked before any dangerous over-voltage conditions can arise. An instantaneous high set over-voltage relay can be provided to trip the generator quickly in in case of excessive over--voltage following a sudden loss of load.
Loss of generator field excitation under normal running conditions may arise due to any of the following condition.
1. Failure of brush gear.
2.unintentional opening of the field circuit breaker.
3. Failure of AVR.
When generator on load loses it’s excitation , it starts to operate as an induction generator, running above synchronous speed. cylindrical rotor generators are not suited to such operation , because they do not have damper windings able to carry the induced currents, consequently this type of rotor will overheat rather quickly.
16.Over-voltage protection
The field excitation system of generators is usually arranged so that over voltage conditions at normal speeds possibly can not occur.the conditions where over-voltage , other than transient over-voltage, do occur is when the prime mover speed increases due to sudden loss of load.the control governors of industrial prime movers are inherently very sensitive to speed changes and the resulting increase from any sudden loss of load is normally checked before any dangerous over-voltage conditions can arise. An instantaneous high set over-voltage relay can be provided to trip the generator quickly in in case of excessive over--voltage following a sudden loss of load.
17. ROTOR EARTH FAULT
The field circuit of generator is not earthed and therefore single earth fault is not considered to be a dangerous condition. However presence of such a fault increases the risk of a second earth fault developing due to increased stresses between rotor winding and earth. The resulting double earth fault will cause part of the rotor winding to become short circuited, with consequence unbalance of the magnetic field produced by the rotor and possibly serious damage to the machine
The field circuit of generator is not earthed and therefore single earth fault is not considered to be a dangerous condition. However presence of such a fault increases the risk of a second earth fault developing due to increased stresses between rotor winding and earth. The resulting double earth fault will cause part of the rotor winding to become short circuited, with consequence unbalance of the magnetic field produced by the rotor and possibly serious damage to the machine
18. Rotor earth fault
Potentio meter method.
AC injection method.
DC injection method
Potentio meter method.
AC injection method.
DC injection method
Posts
0 comments