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Thread: Can anyone see a problem with this Generator set up?

  1. #1
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    Can anyone see a problem with this Generator set up?

    Morning guys and girls.

    Generator questions.



    I have a client who owns 2 warehouses (side by side) in a business park – each with their own supply from the LV room.

    The 1st warehouse has 25mm 3 phase 100-amp supply.

    The 2nd warehouse has a 3 phase 2x25mm SWA parallel supply going to a generator and from the generator its 70mm SWA to the warehouse

    The generator is 250Kva.

    What the client wants to do is supply the 1st warehouse (the one without the generator) from the 2nd warehouse (which has generator back up) when the power goes off.

    I was thinking of running a 16mm (to give them 63 amps) from the 2nd DB (the generator one) to a manual change over switch by the 1st DB.

    I figure if the power goes out (as it often does) the generator will supply DB 2 as normal and then I can run a 16mm to a manual change over at DB 1.
    The manual change over means it won’t be possible to run on normal supply (from the LV room when the power goes back on) and the generator (from DB 2) at the same time.

    Because there are 3 supplies involved (Supply to DB 1, supply to DB 2 and potentially a supply from DB 2 to DB 1 via a manual change over) its making me overthink it.

    Rough sketch added – dotted line being the new 16mm running to a change over switch at DB 1.

    Capacity isn’t a problem. The 250kva is way oversized for one or both warehouse.

    Its just lights, small office’s and few machines. Highest readings at DB 2 are around 30-40 amps per phase. Ware house 1 is literally just lights and one small office

    Can anyone see a problem with that? Running a supply from the generator backed up DB to the 1st ware house?


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  2. #2
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    Hi
    I had a similar question from a contractor a week or so back.
    We did a similar setup with minisubs a couple months back and now doing another one with 4 minisubs and 1 genset
    ATS is a bit more expensive but you can downgrade the genset controller and you don't have control cables to each change over at the individual minisubs.

    In practice I would be more comfortable running from the generator to DB1 and from Genset to DB2
    Even though you aren't, it may appear and could happen, that you run DB2 to DB1 on normal power

    By using an ATS ( Automatic transfer switch) , and I only know about ABB one, you could take a CB and cable from genset to the ATS .
    When the generator starts the ATS will automatically pick up that there is generator power on the switch and change over .When municipal power returns then the ATS will automatically switch back if set to priority.

    You would only need the generator start signal and control cable from DB2 to control generator. The ATS does all the thinking and changing over that would normally be done by a Genset controller and change over switch would do.

    Another advantage of keeping it out of the DB is that it prevents somebody from inadvertently changing phase direction and creating a problem.


    Have pasted a link to a simulator - click on the buttons to get a description
    https://hmi-simulator.s3-us-west-1.a...l-2/index.html

  3. #3
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    The guys at Siemens have a lot of experience dealing with Gen sets safety systems ... synchronizing multi generators and interlocking for shore power etc ... they design and build units for the submarines and all the tugs etc.
    Comments are based on opinion...not always facts....that's why people use an alias.

  4. #4
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    The generator is already in place with ATS in the generator (not at the DB).

    The outgoing cable to DB 2 is in a duct under carpark and there is no route to DB 1 directly from the generator.

    I'm quite happy putting a manual transfer at DB 1 (the one currently without generator back up). I'm putting manual as the ATS at the generator automatically changes to supply DB 2.

    Was thinking of also putting a contactor at DB 1's change over so when mains to DB 1 is on, it drops out the supply coming from DB 2 (whether that be generator on when its on mains).

    Its easy enough to control the supplies so that nothing back feeds or energises at the same time its more an issue with the earthing thats messing with my head.

    They come from the same LV room

  5. #5
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    I would do a recording for at least a week ... understand the load profile of both factories and consider the safest way to do it ... disconnect factory 1 supply and isolate it ... run a 25 mm cable from DB 2 to DB 1.

    This is how we solved this issue ... a big saving only getting one electricity account ... when the company closed down ... we removed the cable and reconnected the old cable and reconnected the meter.
    Comments are based on opinion...not always facts....that's why people use an alias.

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