Power Transformer

technically I don't see the reason. And a lot of transformers are kept for this short duration of time unenergised, unless you are in low temperature regions.

Best to contact the OEMs, some of them ask for some heating provisions if the temperature falls below some value, others are not fussy (ours are not ). Our shed is fed from two sides too (2MVA each), and one is kept off for even longer duration.

Hear is my two cents worth-

I posed a similar question to a transformer manufacture in regards to a solar application. We wanted to switch the transformer off at night to eliminate the NLL.

They said the transformer was not designed to handle repeated inrush currents of re-energization. Better to spend the money on a low loss design.

I think you should alternate transformers less frequently,since you can still run the plant at less the the transformers full load.

Your transformer is Silicon Filled, Indoor? At what temperature will the transformer be at while de-energized. If it is at a mild temperature 75 Degrees F I don't see an issue. Best to always consult the Mfg.

The transformer oil and winding insulation will not deteriorate for keeping it dead. What will affect the winding insulation is the process of disconnecting and reconnecting the transformer every 15 days because overvoltages occur. Also the cooling and heating of the tank leads to mechanical stress within its walls.

You also mentioned something about losses. Sometimes it is more economical to have two transformers at 50% load than one at 100%. Just do the math and find out if really disconnecting one transformer will diminish your bill. Consider that winding loss increases with load, and pretty fast.

Another aspect is related to transformer circuit breakers and other switching devices wear. The open/close cycle for circuit breakers adds up to the cost of exploitation.

I agree, its has been my experience that electrical equipment run better if they run consistent. Building up heat on a piece of equipment then letting it cool down isn't good for any equipment I now of.

Its better to keep some one my age moving as long as you can because once I stop and fall down, I can't get up. Or is that get it up?