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Dilemma on replacing two tranformers with one

Dilemma on replacing two tranformers with one

Dilemma on replacing two tranformers with one

(OP)
I want replace two tranformers with one transformer to feed two buildings. i have a 225kv/208 3 phase transformer thats feeds a 400A 120/208 in building one and 600A 120/208 in building 2. In addition there is a 25kv/240v single phase transformer that feeds a 200A 120/240V single phase pannel in building 1 as well. How do i go abt replacing the two tranformers into one since the 200A pannel in building one has a different voltage rating. Would it be advisable to keep the 25kv tranformer and replace the 225KV tranformer instead?

RE: Dilemma on replacing two tranformers with one

Your single phase panel loads can be connected to two phases and the neutral of a 208Y/120 V source.  The phase to neutral loads (120 V) will see no difference.

The phase to phase loads will no longer see 240 V, but will instead see 208 V.  In many cases, this makes no practical difference, in others, it can cause problems.  It is best to survey the phase to phase loads on the 240/120 V panel:

Look at motor nameplates; many are rated 200/230 V and will work fine with a 208 V input.  If rated only 230 V, look at the loading.  A lightly loaded motor will likely handle the 13% voltage reduction with equanamity; a more heavily loaded motor may not.  Some motors may have 208 V taps.

Look at resistive loads such as heaters; unlike motors which draw more current with less voltage, heaters just produce somewhat less heat.  This would be critical only in highly specialized situations.

HID lighting usually has multi-tap ballasts, and so can be adjusted.  Electronics such as power supplies, VFDs, and so on most likely will be indifferent, but look at nameplates and contact manufacturers if needed.

Changing single phase loads from 'straight' 240/120 V to 'bent' 208/120 V is usually not a huge deal because the bulk of the loads are 120 V phase to neutral, and see no difference.  Those phase to phase loads that exist usually get along fine, and/or can be adjusted to work.

RE: Dilemma on replacing two tranformers with one

(OP)
@ sorry its KVA

RE: Dilemma on replacing two tranformers with one

(OP)
@potteryshard.. Thank you... that is very informative but what other options do i have if i want to maintain the 240V without rating it down to 208.

RE: Dilemma on replacing two tranformers with one

Chances are Potteryshard is correct, but if someone is requesting to keep 240V for just a couple of loads, then the cost of the 240V transformer may be more costly than the cost of replacing the loads that require the 240V to 208V.  You will have to survey what equipment will not accept 240V.  Also, the use of an autotransformer may be another option.  The autotransformer can be used to step the voltage up (or down) from/to 208 to 240V.    

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