Power Transformers Blog – Expert Safety and Usage Info

What do you do if your manufacturing company suddenly loses its main 5000 kva, 34.5 kv to 480 volt transformer? You have orders pending. And if you can’t fill them, a key account may go elsewhere. You have employees suddenly out of work.  You need to heat the buildings.  And you are told it will take 10 weeks to get a new replacement transformer. This is one of a manufacturer’s worse nightmares. What to do? This happens more frequently than one may realize. MIDWEST actually recommends a “Disaster Action Plan,” on the shelf, ready to go, in case of such a nightmare.

MIDWEST receives these calls all too frequently. You might be fortunate and MIDWEST have a replacement reconditioned or used 5000 kva transformer that can be shipped immediately. No one has new transformers this size in stock. And many companies will not accept anything but a new replacement power transformer. In that case, the best solution is to rent a temporary transformer that will provide power until a new replacement transformer can be specified and manufactured. A new replacement transformer may take 10 weeks.

Renting transformers, and other electrical equipment, is a common solution to this critical problem. The first big question to ask when such an emergency occurs is, “Do you want power back on permanently as quickly as possible or do you just want power back on as quickly as possible?”  There is a huge difference in the time to perform either of these solutions. And way too often there is the presumption that one just must get power back on permanently. This presumption continues until the customer realizes how long it will actually take. Meanwhile many hours, even days, are wasted by chasing the wrong solution.

So the most critical event is to decide how fast one wants power restored.  MIDWEST has transformers, temporary high voltage cables and low voltage cables, and switches in stock.  But, more important, is the knowledge that temporary power installations can be a life saver for a facility that is suddenly down.

MIDWEST replaced the old main electrical power transformers for a manufacturing facility.  When we were done, the outdoor substation looked barren. It looked like the power capacity went way down.  We removed one 1000 kva oil filled three phase Westinghouse transformer, one 1000 kva oil filled three phase GE General Electric Transformer, and three 167 kva single phase oil filled transformers. We replaced all these transformers with one new oil filled 3750 Kva transformer. We replaced the concrete pad, of one of the old 1000 kva transformers, with a larger pad. Installed a new grounding system and replaced the fencing. But the new installation made the substation look bare.  Where there were five old oil filled transformers, there was now one new oil filled power transformer. The new 3750 kva transformer wasn’t much larger than one of the old scrap 1000 kva transformers. But, when you looked at the substation, you saw four abandoned concrete pedestals for the removed transformers. And that made the place look like it was going out of business, rather than growing.

The size of many very old GE General Electric, Westinghouse, and especially Allis Chalmers oil filled electrical power transformers was a third to even 100% larger than a new same Kva power transformer. Pad mount transformers are especially smaller because of their low profile.  The low profile green box pad mount transformers got extensive early use in subdivision developments, where the new owners of dream homes didn’t want ugly electrical overhead lines and transformers outside their windows. The little green boxes were small and everywhere, but there were barely noticeable because of their size and color.

So, for electrical power transformers, new is less, less space that is.  

MIDWEST was challenged by a technical skeptic to give him just one example of a large old oil filled transformer that obviously outlasted its useful life expectancy.  Apparently he got into a heated argument with some old timer electricians who claimed they trusted the old transformers a lot more than new stuff they had seen.  It may not be wise to argue with experienced electricians.  They have ways to argue with enthusiasm and sometimes expressions that leave little doubt as to the strength of their convictions.  And they have real world experience, usually a good trump card. 

 MIDWEST gave him the example of two 2000 Kva old substation transformers built in the 1950s that have been running at 107% full load for the last 20 years.  These are not rebuilt or reconditioned transformers.  But they are pretty inefficient and about 3 times as large as a new oil transformer the same kva.  MIDWST is not suggesting old transformers are better than new.  But, be careful when buying new transformers.  Specify quality and reliability, or you may get cheap and disposable.