Connecting Transformers in Series
Connecting Transformers in Series
(OP)
I want to connect the secondary side of two 120/240V transformers in series to get 480V. The transformers are 10 kVA units (additive polarity). The H1 bushings will be tied to the same primary phase, each with its own fused protection (cutout). H2 bushings will be tied to the system neutral. On the secondary side, tie X3 of transformer A to X1 of transformer B. Then I should have 480 V across the remaining X3/X1. For the service wire ground, can I tie it directly back to the system neutral(ground)?
Assuming I use identical transformers(voltage rating, imp., etc.), will this work? Anything I need to watch out for?
Thanks.
Assuming I use identical transformers(voltage rating, imp., etc.), will this work? Anything I need to watch out for?
Thanks.






RE: Connecting Transformers in Series
RE: Connecting Transformers in Series
RE: Connecting Transformers in Series
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RE: Connecting Transformers in Series
RE: Connecting Transformers in Series
Series secondaries do not seem to be prohibited in IEEE C57.12.70-2000, but not directly permitted either. If the transformers have 30kVBIL secondaries, it sounds OK. If applicable, secondary-side metering, overcurrent protection and grounding should be considered.
RE: Connecting Transformers in Series
Why not just get a 120 to 480v transformer, or fixtures with a 240v ballast?
RE: Connecting Transformers in Series
steve066, I think you have a valid point, but would a center-grounded 240/480V 3-wire configuration be so different than part of a 3ø grounded-wye—grounded-wye bank with one primary fuse open? From an operational standpoint, the two transformers could be considered a ‘transformer bank,’ but a single-phase one.