Kafa da Tsuron Kable ko Kawoƙi

Saboda hanyar kawo gaba da yanayi na kawo gaba yana da tsari mai zurfi da yake daɗe a cikin jirgin sama, yadda aka iya faru abin da ke faruwa a cikin hanyar kawo gaba da yanayi na kawo gaba yana da muhimmanci da yawa daga transformer da alternators. Saboda haka, hanyar kawo gaba yana buƙata masu sauri da yawa daga transformer da alternator.
Sauri da hanyar kawo gaba ya kamata a taka shiga wasu muhimman kayan adi, kamar-

1. A lokacin da abin da ke faruwa, kawai circuit breaker mai girma zuwa wurin da abin da ke faruwa yana da ita zai faru.

2. Idan circuit breaker mai girma zuwa wurin da abin da ke faruwa ba su faru, circuit breaker na biyu wanda yake da kyau zuwa wannan breaker zai faru a matsayin backup.

3. Wakar faruwar relay wanda ake sanya da sauri da hanyar kawo gaba ya kamata a taka da tsari mai zurfi saboda hakan don in bincika faruwar circuit breakers wadanda suka duba waɗannan mafi girma da dama.

Wasu muhimman kayan adi masu amfani da su sun haifar da sauri da hanyar kawo gaba yadda yake da yawa daga sauri da transformer da wasu wurare na kawo gaba. Wata uku na masu amfani da su a kan sauri da hanyar kawo gaba sun hada da -

1. Time graded over current protection.

2. Differential protection.

3. Distance protection.

Time Graded Over Current Protection

Wannan zai iya a nufin da kuma a taka shiga over-current protection da hanyar kawo gaba. Ba a tabbatar da wasu tasiri na time graded over current protection.

Protection of Radial Feeder

A cikin radial feeder, kawo gaban yana da hanyar gaba da kima, wanda yake da source zuwa load. Wannan fannonin feeders za a iya sauranta da ma'adan amfani da definite time relays ko inverse time relays.

Line Protection by Definite Time Relay

Wannan fasahar sauri ta shafi shi ne. A wannan fasahar, ana koyar hanyar kawo gaba a cikin wasu manyan sections, kuma ana bayyana har section da definite time relay. Relay mai girma zuwa tsakiyar hanyar kawo gaba yana da setting mai tsari mai kafa, sannan setting mai tsari na relay masu biyu suna yi nasara, zuwa source.
Misali, idan akwai source a point A, a darura da taka

A point D, circuit breaker CB-3 an fitowa da setting mai tsari na relay operation 0.5 sec. Sannan, a point C, an fitowa circuit breaker na biyu CB-2 da setting mai tsari na relay operation 1 sec. Circuit breaker na uku CB-1 an fitowa a point B wanda yake da kyau zuwa point A. A point B, an set relay a tsari mai faruwa 1.5 sec.
A nan, idan akwai abin da ke faruwa a point F. Saboda wannan abin da ke faruwa, an samu fault current a cikin duka current transformers or CTs wadanda suka duba a cikin hanyar kawo gaba. Amma saboda tsari mai faruwa na relay a point D yana da kafa, CB-3, wanda yake da kyau zuwa relay yana faru kafin bincika faulty zone daga wata part of the line. Idan ba su faru ba, inda, relay na biyu wanda yake da kyau tsari yana faru don in faruwa associated CB. A wannan lokacin, CB-2 zai faru. Idan CB-2 ba su faru ba, inda, circuit breaker na uku, yana da kimanin CB-1 zai faru don in bincika major portion of the line.

Advantages of Definite Time Line Protection

Muhimman fa'idar wannan fasahar shi ne simplicity. Fa'idar biyu shine, a lokacin da abin da ke faruwa, kawai CB mai girma zuwa source zuwa wurin da abin da ke faruwa yana faru don in bincika specific position of the line.

Disadvantage of Definite Time Line Protection

Idan number of sections a cikin hanyar kawo gaba yana da kafa, setting mai tsari na relay mai girma zuwa source yana da kafa. Saboda haka, a lokacin da abin da ke faruwa zuwa source yana da kafa, za a iya karɓar da lokacin da take bincika. Wannan zai iya haifar da mutu mai yawa a cikin system.

Over Current Line Protection by Inverse Relay

Drawback wanda a tabbatar a definite time over current protection of transmission line, zai iya haifar da ma'adan amfani da inverse time relays. A inverse relay, lokacin da take faruwa yana da mu'amala da fault current.

A darura da taka, overall setting mai tsari na relay a point D yana da kafa, sannan setting mai tsari na relay masu biyu suna yi nasara zuwa points towards point A.
Idan akwai abin da ke faruwa a point F, zai faruwa CB-3 a point D. Idan ba su faru ba, CB-2 zai faruwa saboda overall setting mai tsari na relay a point C yana da kafa.
Amma, idan setting mai tsari na relay mai girma zuwa source yana da kafa, amma zai faruwa a lokacin da kafa, idan abin da ke faruwa mai yawa yana faruwa zuwa source, saboda lokacin da take faruwa yana da mu'amala da fault current.

Over Current Protection of Parallel Feeders

Don in lura stability of the system, yana buƙata a kunna load da source da two or more than two feeders a cikin parallel. Idan abin da ke faruwa yana faruwa a cikin one of the feeders, kawai wannan faulty feeder zai bincika daga system don in lura continuity of supply from source to load. Wannan buƙatar shi yana haifar da sauri da parallel feeders little bit more complex than simple non direction over current protection of line as in the case of radial feeders. The protection of parallel feeder requires to use directional relays and to grade the time setting of relay for selective tripping.

Akwai two feeders connected in parallel from source to load. Duk duka feeders suna da non-directional over current relay a source end. Waɗannan relays suna buƙata inverse time relay. Kuma duka feeders suna da directional relay ko reverse power relay a their load end. The reverse power relays used here should be instantaneous type. Yana nufin cewa waɗannan relays suna faruwa a lokacin da flow of power a cikin feeder yana rubuta. The normal direction of power is from source to load.
A nan, idan akwai abin da ke faruwa a point F, misali fault current yana da If. Wannan abin da ke faruwa zai samu two parallel paths from source, one through circuit breaker A only and other via CB-B, feeder-2, CB-Q, load bus and CB-P. Wannan yana da bayanin a darura da taka, inda IA and IB are current of fault shared by feeder-1 and feeder-2 respectively.

A cikin Kirchoff’s current law, IA + IB = If.

A nan, IA yana faruwa through CB-A, IB yana faruwa through CB-P. Saboda direction of flow of CB-P yana rubuta, zai faruwa instantly. Amma, CB-Q ba zai faruwa ba saboda flow of current (power) a cikin this circuit breaker ba rubuta ba. A lokacin da CB-P zai faruwa, fault current IB zai stop faruwa through feeder and hence there is no question of further operating of inverse time over current relay. IA still continues to flow even CB-P is tripped. Then because of over current IA, CB-A will trip. In this way the faulty feeder is isolated from system.

Differential Pilot Wire Protection

Wannan shine differential protection scheme applied to feeders. Several differential schemes are applied for protection of line but Mess Price Voltage balance system and Translay Scheme are most popularly used.

Merz Price Balance System

The working principle of Merz Price Balance system is quite simple. In this scheme of line protection, identical CT is connected to each of the both ends of the line. The polarity of the CTs is same. The secondary of these current transformer and operating coil of two instantaneous relays are formed a closed loop as shown in the figure below. In the loop pilot wire is used to connect both CT secondary and both relay coil as shown.