Din Tsohon Farko na Kisan Rotor da Turbinar da ko Generator
Rotor na alternator yana kula da field winding. Idan akwai wasu abubuwa daban-daban a cikin field winding ko a cikin exciter circuit, ba zan iya haifar da wannan shi zuwa makaranta. Amma idan abubuwan da suka faru suna da duka biyu, zai iya samun fuskantar tsari a cikin abubuwan da suka faru. Wannan fuskantar tsari a cikin winding zai iya haifar da magnetic field da ba ta dace, kuma zai iya samun nasarorin mechanical a bearing na makaranta saboda rotation da ba ta dace.
Saboda haka, ita ce ya danganta da gaskiya a tabbatar da abubuwan da suka faru a cikin rotor field winding circuit kuma a gyaran da shi don ilimi mai kyau na makaranta. Akwai wasu tushen da za a iya amfani da su don tabbatar da rotor earth fault na alternator ko generator. Amma yanayi na tushen da duka suke ke sama, wanda ya fi inganci a yi shi shine mafi girman relay circuit through the earth fault path.
Akwai uku tushen rotor earth fault protection da ake amfani da su don wannan abin da.
Potentiometer method
AC injection method
DC injection method
Ba za a tabbata tushen kadan-kadan.
Potentiometer Method of Rotor Earth Fault Protection in Alternator
Tushen ya fi damar. A nan, an sanya resistor wanda yake da balo da ma'ana a kan field winding da kuma a kan exciter. An sanya resistor da central tap kuma an sanya shi a kan ground via voltage sensitive relay.
Kamar yadda ake duba a cikin figure, idan akwai abubuwa a cikin field winding ko a cikin exciter circuit, zai iya haifar da relay circuit through earthed path. A cikin wata lokaci, an zama voltage across the relay saboda potentiometer action of the resistor.
Wannan tushen mai kyau na rotor earth fault protection of alternator yana da batu mai yawa. Tushen ya fi damar a tabbatar da abubuwan da suka faru a cikin abubuwan daban-daban sai dai center na field winding.
Daga cikin circuit, an samu cewa idan akwai abubuwa a kan center na field circuit, ba zan iya haifar da voltage across the relay. Yana nufin cewa simple potentiometer methods of rotor earth fault protection, ana iya tabbatar da abubuwan da suka faru a cikin abubuwan daban-daban sai dai center na field winding. Wannan matsaloli zai iya haifar da aiki a bangaren another tap on the resistor somewhere else from the center of the resistor via a push button. Idan ake bude push button, center tap zai haifar da shi kuma zai iya haifar da voltage across the relay hatta a lokacin da central arc fault occurs on the field winding.
AC Injection Method of Rotor Earth Fault Protection in Alternator
A nan, an sanya voltage sensitive relay a kan abubuwan da suka da field and exciter circuit. Terminal na biyu na voltage sensitive relay an sanya shi a kan ground by a capacitor and secondary of one auxiliary transformer kamar yadda ake duba a cikin figure.
A nan, idan akwai abubuwa a cikin field winding ko a cikin exciter circuit, zai iya haifar da relay circuit through earthed path, kuma zai iya haifar da secondary voltage of the auxiliary transformer across the voltage sensitive relay and the relay will be operated.
Batu mai yawa na tushen shine, zai iya samun leakage current through the capacitors to the exciter and field circuit. Wannan zai iya haifar da unbalancing in magnetic field and hence mechanical stresses in the machine bearings.
Batu mai yawa na tushen shine, saboda akwai different source of voltage for operation of the relay, thus the protection of rotor is inactive when there is a failure of supply in the AC circuit of the scheme.
DC Injection Method of Rotor Earth Fault Protection in Alternator
Matsaloli na leakage current na AC injection method zai iya haifar da a DC Injection Method. A nan, an sanya terminal na biyu na DC voltage sensitive relay a kan positive terminal na exciter and another terminal of the relay an sanya shi a kan negative terminal of an external DC source. External DC source an samu daga auxiliary transformer with bridge rectifier. A nan, an sanya positive terminal na bridge rectifier a kan ground.
Kamar yadda ake duba a cikin figure, idan akwai field earth fault ko exciter earth fault, positive potential na external DC source zai iya haifar da terminal na relay wanda an sanya shi a kan positive terminal na exciter. Hakanan, output voltage na rectifier zai iya haifar da voltage relay and hence it is operated.
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