Q&A da Kiyasin Haɗin Yakin Ƙarfin Makinta da Ingantattun Aiki: Tabbatar Da Funtuɓi Masu Muħimmanci da Abubuwa na Iyakokin Amfani
Misali mai zama na kula da al'amari?
Amsa: Misali mai zama na kula da al'amari shi ne wani babban kayan da ya iya gano hanyoyi ko kuma yadda ake yi a cikin tattalin kula ta mafi girma, kuma ya yi abubuwa don koma kula da sauran nuna bayanan hanyoyi.
Me ke so kuɗi game da misali mai zama na kula da al'amari?
Amsa:
Koma kula da tsohon kayan da ke hankali a cikin tsarin kula, ba da kuma kula da abubuwan da suka fi kan hankali, don in iya ba da aiki masu inganci ga kayan da ba suka haifi ba, kuma in bude lalacewar da ya haifi.
Gano hanyoyi masu yadda ake yi a cikin tattalin kula, kuma ba da abubuwan da za su iya haifi ko kuma zama hanyoyi idan an yi aiki a matsayin. Abubuwan da za su iya haifi ba suka bukatar aiki mai sauƙi, amma za su iya da yanayi, kuma za su iya da tsakiyar zuwa.
Me ke so kuɗi game da misali mai zama na kula da al'amari?
Amsa: Misali mai zama na kula da al'amari yana da muhimmanci sosai wajen inganta aiki da dama, da kuma inganta tattalin kula, kuma wajen koma hanyoyi da kusa. Saboda haka, za a tabbatar da abubuwan da suke da waɗannan ma'ana:
Bayyana: Idan an samun hanyar a cikin tsarin kula, abubuwan da ke hankali ba suke koma kula da kayan da ke haifi, kuma suke ba da aiki masu inganci ga kayan da ba suka haifi, kuma in bude lalacewar da ya haifi.
Sauƙi: Idan an samun hanyar, kuma ba a koma kula da kusa, za su iya zama mai yawa. Misali, a lokacin hanyar, voltaji ya zama ɗaya, wanda ya haifar da motoron da ke kusa da wurin hanyar zuwa ko kuma haifar da aiki. Kuma, generatoron ba su iya bayar kula a lokacin hanyar, wanda ya iya haifar da tattalin kula. Kuma, kayan da ya haifi yake da kula mai hanyar mai yawa, wanda ya haifar da kawo karfi da hoton da ya haifi. Yanayi da kula mai hanyar yake da su, yana haifar da kawo karfi da hoton da ya haifi. Saboda haka, idan an samun hanyar, abubuwan da ke hankali suke koma kula da kusa.
Haushe: Abubuwan da ke hankali suna da muhimmanci wajen gano hanyoyi da kuma yadda ake yi a cikin tattalin kula da suke hankali. Yana nufin cewa suke koma kula da kusa saboda hanyoyi masu uku a lokacin da ake yi aikin da suke da damar, kuma saboda hanyoyi masu biyu a lokacin da ake yi aikin da suke da damar ɗaya, kuma suke koma kula da kusa.
Amanna: Amannar abubuwan da ke hankali yana da muhimmanci. Ba suke ba koma kula idan an samun hanyar a cikin tattalin kula da suke hankali, kuma ba suke koma kula idan ba a samu hanyar. Abubuwan da ba su amanna ba, idan an yi aiki, suna iya zama take da za su iya haifar da yanayi ko kuma haifar da hanyoyi.
Bayyana abubuwan da ke hankali da suke amfani da su a cikin transformer da kuma ayyuka da suke yi.
Amsa: Transformer suna da muhimmanci a cikin tattalin kula. Hanyoyi da suka samu a cikin transformer suna haifar da amanna da kuma aiki masu daidai. Transformer da suke da muhimmanci da kuma adadin kula mai yawa, suna buƙata a yi abubuwan da ke hankali da muhimmanci da kuma amanna.
Hanyoyi da suka samu a cikin transformer suna da hanyoyi masu cikin tanki da hanyoyi masu waje tanki.
Hanyoyi masu cikin tanki suna da: Hanyoyi masu biyu, hanyoyi masu turn, da kuma hanyoyi masu faduwa. Kula mai hanyar suna haifar da kabu, insulatoci, da kuma core, kuma suke iya haifar da vaporization mai yawa da kula da transformer, wanda ya iya haifar da tanki.
Hanyoyi masu waje tanki suna da:Hanyoyi masu biyu da kuma hanyoyi masu faduwa a bushings da kula da gwamnatoci.
Yadda ake yi a cikin tattalin kula suna da: Kula mai yawa saboda hanyoyi masu waje, kula mai yawa saboda wasu abubuwa, da kuma ƙasa mai ƙara a cikin tanki.
Saboda hanyoyi da yadda ake yi a cikin tattalin kula, za a yi abubuwan da ke hankali masu waɗannan:
Gas (Buchholz) protection for internal tank short circuits and low oil levels.
Longitudinal differential protection or instantaneous overcurrent protection for multi-phase short circuits in windings and leads, ground faults on windings and leads in high-current grounding systems, and turn-to-turn short circuits.
Overcurrent protection (or overcurrent protection with compound voltage start or negative-sequence current protection) for external phase-to-phase short circuits, serving as backup for gas and differential (or instantaneous overcurrent) protection.
Zero-sequence current protection for external ground faults in high-current grounding systems.
Overload protection for symmetrical overloads, etc.
What protections are installed for a 600MW generator-transformer (gen-transformer) unit?
Answer:
Generator-transformer unit differential protection
Generator longitudinal differential protection
Main transformer differential protection
Generator loss-of-excitation protection
Generator out-of-step protection
Generator reverse power protection
Generator low-frequency protection
Over-excitation protection
Generator stator ground fault protection
Generator overcurrent protection
Generator inverse-time negative-sequence overcurrent protection
Generator stator overload protection
Generator water-loss protection
Main transformer neutral-point zero-sequence current protection
Main transformer gas (Buchholz) protection
Main transformer pressure relief protection
What are the differences between main transformer differential and gas protection? Can both protections detect internal transformer faults?
Answer: Differential protection is the primary protection for transformers; gas protection is the main protection for internal transformer faults.
The protection range of differential protection covers the primary electrical equipment between the current transformers on all sides of the main transformer, including:
Multi-phase short circuits on transformer leads and windings
Severe turn-to-turn short circuits
Ground faults on winding leads in high-current grounding systems
The protection range of gas protection includes:
Internal multi-phase short circuits in the transformer
Turn-to-turn short circuits, and short circuits between turns and the core or outer shell
Core faults (such as overheating and damage)
Low oil level or oil leakage
Poor contact in tap changers or defective welding of conductors
Differential protection can be installed on transformers, generators, bus sections, and transmission lines, while gas protection is unique to transformers.
For internal transformer faults (except minor turn-to-turn short circuits), both differential and gas protection can respond. Because internal faults cause oil movement and increased primary current, both protections may activate. Which one operates first depends on the nature of the fault.
What types of faults do main transformer neutral-point zero-sequence overcurrent, gap overcurrent, and zero-sequence overvoltage protect against? What are the setting principles?
Answer: Main transformer neutral-point zero-sequence overcurrent, gap overcurrent, and zero-sequence overvoltage protections are designed to protect against ground faults on the equipment's own outgoing lines. They generally serve as backup protection for grounding faults in the 110–220 kV system on the high-voltage side of the transformer. Zero-sequence current protection is used when the transformer neutral is grounded; zero-sequence voltage protection is used when the neutral point is ungrounded; and gap overcurrent protection is used when the transformer neutral is grounded through a spark gap.
The zero-sequence overcurrent protection has a small starting current, typically around 100 A, with an operating time of about 0.2 seconds. Zero-sequence overvoltage protection is typically set at twice the rated phase voltage. To avoid transient overvoltages during single-phase grounding, the time delay is usually set to 0.1–0.2 seconds. The spark gap length at the 220 kV side neutral point of a transformer is generally 325 mm, with a breakdown voltage RMS of 127.3 kV. When the neutral voltage exceeds the breakdown voltage, the gap breaks down, allowing zero-sequence current to flow through the neutral point. The protection time is set to 0.2 seconds.
What are primary protection and backup protection?
Answer: Primary protection refers to protection that, upon a short-circuit fault, meets system stability and equipment safety requirements, and selectively trips to clear faults on the protected equipment and entire line.
Backup protection refers to protection that clears faults when the primary protection or circuit breaker fails to operate.
What is the function of generator forced excitation?
Answer:
Enhances power system stability.
Enables rapid voltage recovery after fault clearance.
Improves the reliability of time-delayed overcurrent protection operation.
Improves the self-starting conditions of motors during system faults.
