Pêşkêşkirina Pêwistîna Jeneratora

Taybetîna Lêzêdina Bistîn

Lêzêdina bistîn dibe heta çavkaniya taybetîna bêtikin, ku bistîn dikare wek bi sêpeyê yekêm hatine biçine.

Rejimê Gênaretora Induction

Bê taybetî, gênaretor dikare were gênaretor induction, ku dikare lêser kirina wergera ve û pirkeriya baran deşike.

Parastina Rêlaya Undercurrent

Rêlaya undercurrent dikare parastin bide lêzêdina sazê heta di demê da taybetîya vêrist bike li ser nisbeteyek din.

Ev rêlay êkara heta taybetîya vêrist bike li ser nisbeteyek din, yekemî 8% ji derbarê taybetîya full load. Heta circuitê sazê raqîb bikin, bê rengirina excitera, deregeha induced li ser sêpeyê slip dikare rêlaya bide pick up û drop off. Ev dikare destkirib bide heta settingsê rêlaya rûsed bike.

Settingê 5% ji derbarê taybetîya normal full load piştgirî dike. Rêlaya undercurrent ya contactê normally closed êkara bikin heta rêlay coil energized bike ji tarafê shunted taybetî. Heta systemê taybetîya bêtikin, rêlay coil de-energises, û contact bikin close û şerazê bide timing relay T1.

Heta rêlay coil energized bike, contactê normally open êkara bikin close. Ev contact supply bikin across another timing relay T2 ji delayê pickup time adjustable 2 to 10 seconds. Relay T1 êkara time delayed on drop off bide stablîze scheme again slip frequency effect. Relay T2 êkara contacts close after the prescribed time delay to either shut down the set or initiate an alarm. It is time delayed on pickup to prevent spurious operation of the scheme during an external fault.

Timing Relays for Stability

Using timing relays helps stabilise the protection scheme against slip frequency effects and prevent false operations.

We know that system voltage is the main indication of system stability. Therefore the offset mho relay is arranged to shut the machine down instantaneously when operation of generator is accompanied by a system voltage collapse. The drop in system voltage is detected by an under voltage relay which is set to approximately 70 % of normal rated system voltage. The offset mho relay is arranged to initiate load shedding to the system up to a safe value and then to initiate a master tripping relay after a predetermined time.

Advanced Protection for Large Generators

For larger generators, advanced schemes with offset mho relays and under voltage relays are used to maintain system stability through load shedding and master tripping relays.