Power transformer Grid station fire in Pakistan (career story)

June 4th, 2019 | Posted in Electrical Safety
Tags: , ,
electrical installation fire

Let’s continue our saga about electrical installations that caught FIRE with another career story sent by an electrical engineer from Pakistan. In fact, Muhammad experienced a transformer fire incident. Learn and enjoy!

Hi everyone! Working for a power utility company with overloaded systems and countrywide power shortage is a challenging job. I work as an assistant manager for National Transmission and Dispatch Company (NTDC) of Pakistan…

I have a team of 15 persons (10 linemen, 2 riggers and 2 supervisors along with 1 data operator). Our primary job is to mitigate transmission line faults in a designated area i.e. Pattoki, a small city in the province of Punjab.

EHT gantry in Punjab, Pakistan

Pattoki substation (locals call it a grid station) is one of the important substations of Pakistan’s transmission network feeding almost 300 megawatts of electrical energy. Pattoki is an industrial city and majority of the MV feeders are utilized directly by the small textile industries. Transmission and grid maintenance teams are always standing by at the grid station for a prompt fault response and routine maintenance.

Electrical transformer FIRE incident

It was just another Sunday and I was lazily wasting my time lying in the bed. At around 10 am I received an email by the safety department informing all the departments about an un-extinguished fire at Pattoki grid station.

Transformer fire at the grid station

Following the fire, all the load lines connected with the affected grid were turned off for safety reasons. The only active load was the auxiliary transformer and load management was on hold till the arrival and subsequent decision of HSEQ (Health, Safety, Environment and Quality) department.

Fire brigade was also helpless and an on-site command center was established followed by a careful analysis of the emergency. Whole transformer (Siemens, 40MVA ONAN) was engulfed in the fire and it was declared too dangerous to be approached by firefighting teams and technical staff. There was nothing much our teams could do except coordinating the updates and recording video footages. I reached at the site at 3 pm and the fire was still not extinguished. However shortly afterwards, the fire brigade sprayed some fire suppressant and luckily the fire was slowly strangled.

Cleaning and environment control teams worked for more than twenty four hours and the contaminants were contained within the spill pit of the transformer. Load was managed and shifted to healthy bus bars but the affected transmission line remained offline. Main droppers of the affected transmission line (Blue and yellow phase) were also found broken. The subject transformer was completely destroyed and was declared unfit for repair.

Electrical transformer FIRE aftermtaths

Technical teams spent hours inside the transformer yard and several protection tests were conducted to evaluate the initial data which might help the departmental investigation. An eleven KV (medium voltage) trolley was also found flashed after the fire and CCTV camera footage confirmed that it happened after the eruption of transformer fire. Protection schemes were also found affected by the resultant surge of the fault current and the cause of primary fire remained masked behind a number of technical complexities.

Switchgear damaged along with the protection panel

During the investigation my department was also inquired because of a recent maintenance activity on the transmission line. Inquiry head pointed out the broken droppers of the transmission line and questioned possible relation between the resultant spark and transformer fire. Video footage recorded by a lineman of our department (who was incidentally present at the affected grid during the time of accident) showed intact droppers even into the tenth minute of the transformer fire and the suspicion was ruled out immediately. This was a big relief for me and my team as well.

Later on, after extensive inquiries and cross departmental investigations, the cause of fire was declared to be fatigue related material failure or some unknown fault in protection scheme. However, protection department was issued a show-cause notice and was instructed to initiate the re-inspection process of grid protection system.

Electrical transformer FIRE incident: Summary

A Siemen’s 40 MVA ONAN power transformer failed and was destroyed when its mineral oil caught fire. The exact fault which caused the fire remains undiscovered because a lot of evidence was destroyed due to the primary fire and short circuit itself.

However the protection department was warned to remain more cautious and to be prepared for incidental fires with better protection schemes and data recorders.

Thanks for reading my story everyone,
E.E Muhammad

If you’ve ever experienced this type of tranformer or electrical installation incident, don’t hesitate to write a comment below. Of course, the cause of the fire has to be electrical.

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