lyledunn:
Just as a matter of interest OMS, what type of tx do you specify? I am sure fire safety is a crucial aspect.
Depends on where they are situated and what type of load profile I'm dealing with
Externally, or with suppression if used in basements, with a big variation in load profile, and a credible need to run to emergency ratings then I would use fluid filled hermetically sealed transformers (usually MIDEL or a generic OM16 insulating oil eg Shell Diala)
Internally, or with high harmonic loads, and where suppression isn't practicable, then dry transformers with a high K factor with or without forced air fans if I needed that overload capability
I tend to use copper windings on either type - I'm not a big fan of aluminium windings on reasonably low rated transformers (ie up to about 2.5MVA).
If using dry transformers, I would tend towards combing these as integrated transformer switchboards with the Tier 1 switchgear (up to say 4000A, 80kA 3 second gear)
As usual, it needs the pro's and con,s of each type evaluating for the specific application by the design engineer - so no simple answer along the lines of "but we always do this when...……………"
Regards
OMS
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