POWER TRANSFORMERS – Fires

Text: Radoje Janković.

Photo: Electrical Technology

In the case of large power transformers for high, extra high and ultra high voltages, detailed periodic maintenance is important, control of the appropriate parameters and especially the dielectric strength of the transformer oil which must be minimal within the prescribed values ​​and it is always desirable to be much higher.

Of course, it is also important to control all mechanical and electrical connections of all elements, and in particular the bus connections through which large currents run. The bindings and contacts on the transformers should be controlled with thermovision instruments that detail the temperature of the joints of the almost diagram, and it can be noticed that the defect or eventual start of the future fault is caused, which can cause enormous damage because these transformers are the most expensive equipment in all TS and distribution plants. Removing faults, especially on windings and cores of the transformer, lasts for quite a long time, which entails a long-term absence of transformer from work if there are no spare or possibility to borrow from other plants …

Transformer insulators are very sensitive elements through which conductors run all the currents of a TS or plant. It is therefore very important that they are periodically examined in detail.

In the transformer in figure is a conductive insulator of the so-called. oil – impregnated paper (OIP) bushing – whose conductors through porcelain insulators are insulated with special paper for these purposes and are the same in transformer oil as the entire transformer.

Probably due to inadequate periodic maintenance and testing, the insulation and precipitation of very fine particles were detected on the insulator shield, which led to the ignition due to high loads (large currents), and probably also due to the frequent overload of the transformers, since they must not rarely work in overload regimes .

The damage is very high and the question is whether this transformer can be and whether it is profitable to repair it for reuse.

Firefighters fire a fire to expand as little as possible to the surrounding elements of this high voltage installation, and as the picture shows, the transformer did not have its own fire system for its own and automatic fire extinguishing.

However, it is very often difficult to extinguish the fire on such plants until completely burning oil that is leaking from all sides, which can cause large explosions within the plant and cause even more damage.

Here is a very important specialty of the training of the team for extinguishing these kinds of fires in vital energy facilities, especially the timely intervention of firefighters. It is also most important that the transformer all the time “sinks” with huge amounts of foam for quenching so that the transformer is practically immersed in the foam, so as not to spread the fire – the flames of high temperatures on the pipe bars from the left and right to the pantograph disconnectors / switches as well as to the arresters for protection against atmospheric electricity. If in any case and in practice there is a large explosion of fire and flame, the entire part of the plant around the transformer must be damaged, and then the repair costs are enormous. Transformer is no longer for use, it is necessary to replace new, as well as tubular busbars with accompanying equipment, pantographs or other disassemblies, cathode arrester as well as the entire steel structure of the plant.

I wrote the text from my head, so I apologize to colleagues for some inconsistencies, but everything is clearly stated, which is most important.

APPENDIX:

Large power transformers are designed and manufactured in accordance with very strict technical regulations and all necessary technical calculations and are thoroughly examined at all conditions in the manufacturer’s factory. Also, by the designer and the constructor, all possible technical measures are foreseen to protect the transformer as the most expensive device in large distribution systems. Each producer of the transformer delivers detailed technical instructions for technical maintenance during the operation of large transformers. The problem here is that the staff working in these plants is not properly trained, incompetent, and does not respect all the necessary requirements of the manufacturer for the monthly, semi-annual, annual and five-year servicing and maintenance of these expensive devices. In many companies that have large power plants and transformers, this equipment improperly maintains or is not maintained at all in accordance with the prescribed rules and requirements. As a result, there are usually major accidents. This usually happens in less developed countries, where education of experts for such jobs is very poor and insufficient, and often many are educated at a distance without having to attend vocational schools and technical faculties, so their knowledge is very bad or no. I’m sorry my colleagues, this is what I am saying, but I also had the opportunity to see it many times … Today, many are educated in the educational system of education that is unacceptable for these types of jobs. Etc. etc.

Požari na velikim transformatorima

ENERGETSKI TRANSFORMATORI

Tekst: Radoje Janković.

Kod velikih energetskih transformatora za visoke, ekstra visoke i ultra visoke napone, veoma je važno detaljno periodično održavanje, kontrola odgovarajućih parametara a posebno dielektrične čvrstoće trafo ulja koja mora biti minimalno u okviru propisanih vrednosti a uvek je poželjno da bude i znatno viša.

Naravno, važno je kontrolisati i sve mehaničke i elektro spojeve svih elemenata a posebno sabirničkih veza kroz koje teku velike struje. Sabirničke veze i kontakte na trafoima najbolje je kontrolisati termovizijskim instrumentima koji detaljno pokazuju temperaturu spoja maltgene dijagramski i uve se može uočiti nedostatak ili eventalni početak nastanka budućeg kvara koji može izazvati ogromne štete jer su ovi transformatori najskuplja oprema u svim TS i razvodnim postrojenjima. Otklanjanje kvarova posebno na namotajima i jezgrima trafoa traje dosta dugo što povlači dugotrajno odsustvo trafoa iz rada ukoliko ne postoje rezervni ili mogućnost pozajmici istih od drugih postrojenja…

Izolatori transformatora su veoma osetljivi elementi kroz čije provodnike teku sve struje neke TS ili postrojenja. Stoga je veoma važno da se oni periodično detaljno ispitivaju.

Na trafou sa slike su provodni izolatori tzv. oil – impregnated paper ( OIP) bushing – čiji su provodnici kroz porcelanske izolatore izolovani specijalnim papirom za ove svrhe i isti su u trafo ulju kao i ceo transformator.

Najverovatnije zbog neadekvatnog periodičnog održavanja i ispitivanja došlo je do zaprljavanja izolacije i taloženja veoma finih čestica na drnu izolatora što je dovelo do zapaljivanja usled velikjo opterećenja (velikih struja) a verovatno i zbog čestog preopterećivanja transformatora jer isti moraju ne tako retko da rade i u režimima preopterećenja.

Šteta je veoma velika i pitanje je da li se ovaj transformator može i da li je isplativo da se isti remontuje za ponovno korišćenje.

Vatrogasci gase požar da se što manje proširi na okolne elemente ovog visokonaponsko postrojenja a kao što se sa slike takođe vidi, trafo nije imao sopstveni protivpožarni sistem za sopstveno i automatsko gašenje požara.

No, požar na ovakvim postrojenjima je veoma često teško ugasiti sve dok potpuno ne izgori ulje koje curi na sve strane, i koje može izazvati velike eksplozije u okviru postrojenja i naneti još veće štete.

Ovde je veoma važna specijalnost obučenosti ekipa za gašenje ovakvih vrsta požara kod vitalnih energetskih postrojenja a posebno pravovremenost intervencije vatrogasaca. Takođe je najvažnije da se trafo celo vreme “zasipa” ogromnim količinama pene za gašenje tako da trafo praktično bude potopljen u peni, kako ne bi došlo do širenja požara – plamena visokih temperatura na cevne sabirnice s leve i desne strane koje se vide, na pantografske rastavljače/prekidače kao i na katotne odvodnike za zaštitu od atmosferskog elektriciteta. Ako kojim slučajem a ima ih u praksi dođe do velikog razbuktavanja požara i plamena ceo deo postrojenje oko trafoa obavezno strada, i tada su troškovi remonta ogromni. Trafo više nije za upotrebu, potrebna je zamena novim, kao i cevnih sabirnica sa pratećom opremo, pantografskih ili drugih rastavljača, katodnih odvodnika kao i celokupne čelične konstrukcije postrojenja.

Tekst sam pisao iz glave, tako da se izvinjavam kolegama za neke nedoslednosti, ali je sve jasno rečeno, što je i najvažnije.

DODATAK:

Veliki transformatori snage projektovani su i proizvedeni u skladu veoma strogih tehničkih propisa i svih neophodnih tehničkih proračuna i detaljno ispitani na sve uslove u fabrici proizvođača. Takođe su od strane projektanta i konstruktora predviđene sve moguće tehničke mere za zaštitu transformatora kao najskupljeg uređaja u velikim razvodnim postrojenjima. Svaki proiozvođač uz transformator isporučuje detaljna tehnička uputstva na tehnička održavanja u toku eksploatacije velikih transformatora. Ovde je problem što je osoblje koje radi u ovakvim postrojenjima nedovoljno obučeno, nestručno, i ne poštuje sve potrebne zahteve prozvođača za mesečno, polugodišnje, godišnje i petogodišne servisiranje i održavanje ovih skupih uređaja. U mnogim kompanijama koje imaju velika energetska postrojenja i transformatore ovu opremu neadekvatno održavaju ili je maltene uopšte ne održavaju u skladu sa propisanim pravilima i zahtevima. Zbog toga najčešće dolazi do velikih havarija. Ovo se po pravilu događa u manje razvijenim zemljama i u kojima je obrazovanje stručnjaka za ovakve poslove veoma slabo i nedovoljno, a često puta i mnogi se obrazuju na daljinu bez redovnog pohađanja stručnih škola i tehničkih fakulteta pa im je znanje veoma loše ili nikakvo Žao mi je kolega što ovo govorim ali je tako i imao sam prilike da se mnogo puta u to uverim… Danas se mnogi školuju po sopisnom sistemu obrazovanja koji je nedopustiv za ovakve vrste poslova. Itd. itd.

Photo: Electrical Technology

Original work by author.