Faulti na Kofin da Kofa a Transforma

Yana da kyau a yi inganci masu iya sama da transformer da sauran kashi matafi na gaba da matafi na ciki.

Matafi Na Gaba a Cikin Transformer

Matafi Na Gaba A Cikin Transformer

Matafi na gaba yana iya faru a biyu ko tatuwa masu shugaban kai. Tsarin matafi kai yana da tsari mai kadan. Wannan yana nufin shi daidai. Ana iya ba da tsarin kashi wanda aka gaba da shi. Kai da ya faru ita ce take taimaka da tsarin kai a kan transformer. Tsarin kai na gaba ta zama da karfin kusa da tsarin kai na transformer. Tsarin kai mai kadan tana ba da karfin kusa da tsarin kusa na transformer. Karfin kusan da ke faduwar daidai suka faru a tsohon karamin tsarin kai na gaba.

Matafi Mai Kashi Daidai a Cikin Transformer

Matafi mai kashi daidai a cikin transformer suna da biyu,

1. Tsarin Matafi Mai Kashi Daidai

2. Matafi Mai Kashi Daidai Na Tsarin Kashi

Tsarin Matafi Mai Kashi Daidai

Matafi mai kashi daidai tana iya faru a cikin shugaban kai saboda abubuwan da suka faru waɗannan:

• Karkashin harkar zuwa ground idan wurin neutral an gudanar da shi.

• Gargajiya masu aiki na shugaban kai.

• Karkashin harkar zuwa ground idan wurin neutral an gudanar da shi.

Idan wannan matafi mai kashi daidai ta faru, yana da tsari mai kadan da kuma tsari mai kadan. Wannan tsari yana yi harkar zuwa shugaban kai, idan ya samu transformer, yana ba da karfin kusa da tsarin kusa na turn daga baya zuwa terminal line, wanda zai ba da karfin kusa da tsarin kusa na turn.

Matafi Mai Kashi Daidai Na Tsarin Kashi

Ina da kyau a yi amfani da system over voltage saboda koyarwa masu kasa. Idan tsarin kashi ta fi kadan da tsarin da ake amfani da shi amma tsarin kashi ta fiye daidai. Over voltage a system yana ba da karfin kusa da tsarin kusa na transformer. Idan a sanu, kashi, kashi mai kadan yana ba da karfin kusa da tsarin kusa na working flux.
Wannan yana ba da karfin kusa da iron loss da kuma kai mai kadan. Tsarin kai mai kadan yana ba da karfin kusa da tsarin kusa na core. Core bolts wanda ba suka da tsarin kusa, za su iya da karfin kusa da tsarin kusa na core.

Ayoyinta Tsarin Kashi a Cikin Transformer

Saboda, kashida number of turns in the winding is fixed.
Therefore,
Daga, wannan equation ita ce ina sanu idan tsarin kashi ta fiye a cikin system, tsarin kusa na core yana fiye, abubuwan da suka faru suna daidai da abubuwan da suka faru a cikin over voltage.

Matafi Na Ciki a Cikin Transformer

Abubuwan da suka faru a cikin transformer suna da:

1. Matafi na insulation bayan winding da earth

2. Matafi na insulation bayan different phases

3. Matafi na insulation bayan adjacent turns (inter – turn fault)

4. Matafi na core

Matafi Na Earth A Cikin Transformer

Matafi Na Earth A Cikin Winding Daga Star Connection Ta Neutral Point Earthed Through An Impedance

A cikin wannan, tsarin kai yana da kyau a yi amfani da earthing impedance da kuma yana da kyau a yi amfani da distance between fault point and neutral point saboda tsarin kashi a cikin fault point yana da kyau a yi amfani da number of winding turns come across neutral and fault point. Idan distance between fault point and neutral point yana da kyau, number of turns under this distance yana da kyau, saboda haka tsarin kashi a cikin neutral point and fault point yana da kyau wanda yana ba da karfin kusa da tsarin kai mai kadan. Saboda haka, a cikin kalmomin da suka faru, tsarin kai yana da kyau a yi amfani da value of earthing impedance as well as distance between fault point and neutral point. Tsarin kai yana da kyau a yi amfani da leakage reactance of the portion of the winding across the fault point and neutral. Amma compared to earthing impedance, it is very low and it is obviously ignored as it comes in series with comparatively much higher earthing impedance.

Matafi Na Earth A Cikin Winding Daga Star Connection Ta Neutral Point Solidly Earthed

A cikin wannan, earthing impedance yana da kyau a yi amfani da zero. Tsarin kai yana da kyau a yi amfani da leakage reactance of the portion of winding comes across faulty point and neutral point of transformer. Tsarin kai yana da kyau a yi amfani da distance between neutral point and fault point in the transformer. As said in previous case, tsarin kashi a cikin fault point and neutral point yana da kyau a yi amfani da number of winding turn comes across faulty point and neutral point. Saboda haka, a cikin star connected winding with neutral point solidly earthed, tsarin kai yana da kyau a yi amfani da two main factors, first the leakage reactance of the winding comes across faulty point and neutral point and secondly the distance between faulty point and neutral point. But the leakage reactance of the winding varies in complex manner with position of the fault in the winding. It is seen that the reactance decreases very rapidly for fault point approaching the neutral and hence the fault current is highest for the fault near the neutral end. So at this point, the voltage available for fault current is low and at the same time the reactance opposes the fault current is also low, hence the value of fault current is high enough. Again at fault point away from the neutral point, the voltage available for fault current is high but at the same time reactance offered by the winding portion between fault point and neutral point is high. It can be noticed that the fault current stays a very high level throughout the winding. In other word, the fault current maintain a very high magnitude irrelevant to the position of the fault on winding.

Matafi Na Phase To Phase A Cikin Transformer

Matafi na phase to phase a cikin transformer suna da kyau a yi amfani da substantial current to operate instantaneous over current relay on the primary side as well as the differential relay.

Inter Turns Fault A Cikin Transformer

Transformer connected with electrical extra high voltage transmission system, is very likely to be subjected to high magnitude, steep fronted and high frequency impulse voltage due to lightening surge on the transmission line. The voltage stresses between winding turns become so large, it can not sustain the stress and causing insulation failure between inter – turns in some points. Also LV winding is stressed because of the transferred surge voltage. Very large number of power transformer failure arises from fault between turns. Inter turn fault may also be occurred due to mechanical forces between turns originated by external short circuit.

Core Fault A Cikin Transformer

Idan anyi da portion of the core lamination is damaged, or lamination of the core is bridged by any conducting material that causes sufficient eddy current to flow, hence, this part of the core becomes over heated. Sometimes, insulation of bolts (Used for tightening the core lamination together) fails which also permits sufficient eddy current to flow through the bolt and causing over heating. This insulation failure in lamination and core bolts causes severe local heating. Although these local heating, causes additional core loss but can not create any noticeable change in input and output current in the transformer, hence these faults cannot be detected by normal electrical protection scheme. This is desirable to detect the local over heating condition of the transformer core before any major fault occurs. Excessive over heating leads to breakdown of transformer insulating oil with evolution of gases. These gases are accumulated in Buchholz relay and actuating Buchholz Alarm.

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