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Why the main three phase doesnt have a neutral wire before reaching a stepdown transformer, how does electricity form a loop back to its source
- Jul 22, 2019
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You actually create your neutral in the load side of the transformer. The primary side doesn’t require a neutral in some transformers.
With a three phase system the current from any one phase can return via the other phase(s) depending on the load. So if your load does not need a neutral point (such as a delta-connected motor or transformer primary) you don't need a natural cable! And so you can save significant cable cost on the distribution side.
Once you get to the low-voltage side for general purpose use then it is a convention to provide the neutral. in the UK/EU that is very standard (230V L-N /400V L-L) via a star-connected transformer secondary ('wye' in USA parlance).
The high voltage sending end usually has the neutral mid-point earthed. Sometimes via an impedance designed to control fault currents, etc, and sometimes by means of an earthing transformer if the source lacks a star point (such as an alternator, delta-connected transformer secondary, etc)
en.wikipedia.org
Once you get to the low-voltage side for general purpose use then it is a convention to provide the neutral. in the UK/EU that is very standard (230V L-N /400V L-L) via a star-connected transformer secondary ('wye' in USA parlance).
The high voltage sending end usually has the neutral mid-point earthed. Sometimes via an impedance designed to control fault currents, etc, and sometimes by means of an earthing transformer if the source lacks a star point (such as an alternator, delta-connected transformer secondary, etc)
Grounding transformer - Wikipedia
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- Jul 22, 2019
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On a 3 phase Delta system you don’t have a neutral on the primary side of your transformer. I have worked in a lot of plants with a 3 phase delta system and if something goes to ground it will not blow a fuse or trip a breaker. That’s why most plants with a delta system they usually have 3 lights with each light is phase A, phase B or phase C. If one light is out and the other 2 lights get brighter then they have a grounded phase.
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