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sauravbabu
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Engineering Fields - Electrical Engineering - New Member

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Posts: 247

Interlocking of UAT and DG

08/21/2011 2:15 AM

In a utility system, we are designing with two hydrognerators of 2 MW, with 1 UAT for individual Generator. They will be interlocked so that only one of the UAT will be operational at a time, and when both UAT are not in use, DG will be operated. But is this reliable? I have heard that these get damaged pretty quickly and thus interlocking is not recommended.

Regards,

sks
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Tornado
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Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

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#1

Re: Interlocking of UAT and DG

08/21/2011 2:33 AM

UAT = ?

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TonyS
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#2
In reply to #1

Re: Interlocking of UAT and DG

08/21/2011 5:20 AM

Ultra Alta Temperatura (Portugese: long life milk)

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electricalexpert65
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#3

Re: Interlocking of UAT and DG

08/21/2011 8:23 AM

If the interlocking scheme is good they are pretty reliable and such schemes have been in successful operation.
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67model
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#4

Re: Interlocking of UAT and DG

08/21/2011 11:22 AM
  1. Interlocking is used when the consequences of NOT interlocking will put plant or the station out of operation or damage them. I do not think a competent designer or station manager would recommend doing without them - they would soon recommend doing without those persons who try to bypass such interlocks.
  2. UAT = Unit Auxiliary Transformer. I only know that because a previous post by you was about that. Using Mnemonics, like UAT, rarely helps unless the people you address know well what you mean!
  3. You have not clarified what you mean by "interlocking". Since you have not mentioned the word "automatic" it can easily be a set of mechanical locks and keys on the breakers or their controls which make it impossible to manually energize them in the wrong combinations or sequence.
  4. There are fools who try to bypass interlocks - which may be why they get "damaged pretty quickly".
  5. There are automatic or semi-automatic transfer schemes used for the situation you have and they must have electrical interlocking. Any such interlocking using good design & components would not be damaged by proper use or be unreliable.
  6. It is very possible to design an automatic transfer scheme for the application which is not reliable because it did not allow for all the inherent tolerances or circumstances.
  7. From your description of the plant and its size, transfers could use mechanically and electrically interlocked motor starter contactors from, for example, Telemecanique. Since you have three power sources, such a scheme is not a trivial design exercise.
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