Fires In Substations Transformers

The correct answer is: All of the above. They each have an equal chance of being the cause of a transformer failure, plus you left out a few others that may be significant. Now here's a question for you: what is the purpose of the question? It might help us give you a more informed answer.

IMHO The primary contributor of transformer and sub-station failure is paradoxically the high reliability of most transformers and sub-stations that has spawned an effective "run to failure" operation of many utilities. I'm certain that no utility wishes to operate grid components to failure but getting all of the complicated permissions to turn off part of a neighborhood's power for upgrading and maintenance is rare. Now many but not all sub-stations can be isolated from the grid without impacting service. Even in these cases though, spending money to prevent a problem that can be bypassed can get a low priority on any cost cutting budget.

Thank you RamConsult: Well I wanted to weigh the justification offered by a HV maintenance team in the event of a transformer fire. (I am not considering the general case of a transformer failure). Will they be correct in attributing the fire to multiple failures? Well, we all know that if one level of protection fails, the second should kick in to prevent failure propagation. I ask particularly because I have heard of cases of operational transformers catching fire. The maintenance was running routinely. They had a hell of a time explaining to the authorities where the fault lay. At the end o the long meetings, I do not think either party was convinced.

Redfred seems to have accurately highlighted the managerial policies that could cause such accidents.

Mathew, You have not said if the maintenance team is an independent contractor or employees of the utility, nor have you described what you mean by "...maintenance was running routinely...", or who "...the authorities..." are, so those details might help us. Until then let me suggest that ultimately all transformer failures are due to an internal insulation failure, and having said that, that the cause of those failures runs the gamut from what Redfred said, all the way to absolutely random untraceable events and everything in between.

Different faults leave different "clues" as to what lead to the failure. Typically there is enough evidence for highly trained personnel to agree on a probable cause, whether it be overheating, overloading, lightning, single surges, repetitive surges, improper switching, improper shipping and installation, lack of maintenance, faulty relaying, physical damage, or just dumb luck. I've seen them fail on initial energization after they passed all the factory and field testing perfectly, and I also know that utilities rarely deliberately overload them beyond the manufacturer's recommendations except under extreme system-wide disturbances.

I'm a bit curious how a non-operational transformer would catch fire unless somebody was welding on it, and then the cause would be obvious. What is the underlying motive for your question?

Maintenance is periodically (both preventive and corrective) done by the transmission company's maintenance dept. Authorities refers to the electricity regulators (government side). By operational, I meant live transformer, not one that has just been commissioned (inrush current issues). Like you just broke it down, I wanted to know if if "…there is evidence for highly trained…" then we could have fore-seen some of these disasters?

Dear mathewkyle,

If you carry out root cause analysis of the failed transformer, correct reason of failure can be detected.

Thanks,

Manindra

Manindra, Root Cause Analysis is based on hindsight and seeks to find out what happened after a failure, Mathew should do a Failure Mode and Effect Analysis (FMEA) to consider all the things that can go wrong before they do and then plan accordingly.

You should employ monitors for alarm/trip of vital components.

Hello, Thanks for the great ideas shared.