Power Transformers Blog – Expert Safety and Usage Info

Anyone in our business has seen transformers with concrete pads no longer level.  MIDWEST frequently sees padmount transformers off kilter because the concrete pad has shifted, usually because the soil in one area has washed out.  It occurs far less frequently, but sometimes we see the concrete pad for a large outdoor power transformer has settled on one side, causing the transformer to no longer be level.  Slight settling might not pose a problem. But we frequently, using Infrared Scanning, find old oil filled outdoor power transformers that are not cooling properly.  This occurs when an old electrical power transformer has long cooling tubes.  On some transformers, the oil level may only fill 2/3 of the upper heads for the cooling tubes.  If the transformer is slightly out of level, some of the outer cooling tubes on the transformer may tilt high enough that the oil will no longer reach the head and will not circulate.  These cooling tubes will actually look cold when viewed with Infrared Thermography. 

If you find your transformer is not level or is actually not circulating properly, do not attempt to correct this while the transformer is energized.  This is a very bad idea. You are too close if anything goes wrong. And there are things that can go wrong with oil filled transformers that you can’t even imagine.  Transformers are very heavy, especially old obsolete transformers.  They can get very unhappy and the equipment they are connected to, can get very unhappy and make a big mess, if you try to level them energized.  It’s tempting, because it looks so easy. But, if something goes wrong, it’s hard to get out of the way.

MIDWEST was called on an emergency after a contractor tried to level a 3750 kva, 25 kv to 480 volt transformer, that was connect to service bus. The secondary bus faulted at the transformer throat connection and pretty much destroyed everything, transformer and bus.  What seemed like a good idea one moment, turned into a catastrophe the next. Again, MIDWEST recommends thinking “consequences, not probability.”