Ask Experts Questions for FREE Help !
Ask
    maruli's Avatar
    maruli Posts: 5, Reputation: 1
    New Member
     
    #1

    Aug 1, 2008, 10:04 AM
    How to connect three phase city supply to generator!
    Hi dear 'ask me' community,

    I have a 30KW generator with a automatic transfer switch - it has a three phase input U, V, W and N which
    Needs to be connected to the city power it then has an output that goes to the building. How do I know
    Which phase of the city supply needs to go to the U, V, W and N (neutral). Can an incorrect phase
    Connection cause damage to the generator - how can I avoid this!

    Your help will be greatly appreciated!

    Thanks - Maruli!
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
    Uber Member
     
    #2

    Aug 1, 2008, 10:33 AM
    Please explain your experience with 3 phase.

    I am not familiar with the code letters you refer to "U, V, W and N (neutral)".

    Am I correct you are not located in the USA or Canada?

    Are you familiar with a Phase Rotation instrument?
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
    Uber Member
     
    #3

    Aug 1, 2008, 10:38 AM
    Use a phase sequence meter. Phase Rotation

    Contact the transfer switch manufacturer. As long as the generator and the utility are providing power from the same phase you should be OK as long as the transfer switch doesn't detect phase reversal. Confirm with manufacturer.
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
     
    #4

    Aug 1, 2008, 01:16 PM
    My opinion on this is that this is ABSOLUTELY NOT a DIY job. You should NOT be messing with this stuff, especially if you have to come to a DIY site to ask questions.

    PLEASE call in a professional to do this job for you!
    maruli's Avatar
    maruli Posts: 5, Reputation: 1
    New Member
     
    #5

    Aug 2, 2008, 11:31 PM
    Quote Originally Posted by tkrussell
    Please explain your experience with 3 phase.

    I am not familiar with the code letters you refer to "U, V, W and N (neutral)".

    The generator is a Chinese product - looks like they are using German notation - what I can see from
    the circuit diagram supplied, U=L1, V=L2, W=L3.

    Am I correct you are not located in the USA or Canada?

    Yes I am located in South Africa.

    Are you familiar with a Phase Rotation instrument?
    No - but I would presume it could tell be the 120 deg difference between the phases.

    Thanks.:)
    maruli's Avatar
    maruli Posts: 5, Reputation: 1
    New Member
     
    #6

    Aug 2, 2008, 11:36 PM
    Quote Originally Posted by KeepItSimpleStupid
    Use a phase sequence meter. Phase Rotation

    OK - will try to get hold of one!

    Contact the transfer switch manufacturer. As long as the generator and the utility are providing power from the same phase you should be OK as long as the transfer switch doesn't detect phase reversal. Confirm with manufacturer.
    Will check with manufacturer first.

    Thanks for all your information - much appreciated!:)
    maruli's Avatar
    maruli Posts: 5, Reputation: 1
    New Member
     
    #7

    Aug 2, 2008, 11:46 PM
    Quote Originally Posted by stanfortyman
    My opinion on this is that this is ABSOLUTELY NOT a DIY job. You should NOT be messing with this stuff, especially if you have to come to a DIY site to ask questions.

    Oh I did not know that this is a DIY site I thought I could ask any questions!:(

    PLEASE call in a professional to do this job for you!
    Being in Africa it's often the case that the professional can blow-up your equipment - so it's better
    To research and know exactly what needs to be done yourself!:)
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
    Uber Member
     
    #8

    Aug 3, 2008, 04:58 AM
    Ok.

    Any generator system needs a transfer switch, either a manual unit or automatic.

    This isolates the utility line from the generator output, so the load only connects to either the utility or the generator, and there is no chance of the gen power getting out into the utility lines.


    Simply use a phase rotation instrument to check and note the rotation of utility lines and of the gen output at the transfer switch. If the gen output is different that the utility, simply switch any two wires of the gen output.

    Now the load will be fed by either the genset or utility with matching rotation, or sequence, of phases.
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
     
    #9

    Aug 3, 2008, 06:22 AM
    Quote Originally Posted by maruli
    Being in Africa it's often the case that the professional can blow-up your equipment - so it's better
    to research and know exactly what needs to be done yourself!:)
    Here is yet ANOTHER case of knowing your location FROM THE START would have been a BIG help. :rolleyes:
    maruli's Avatar
    maruli Posts: 5, Reputation: 1
    New Member
     
    #10

    Aug 3, 2008, 09:56 PM
    Quote Originally Posted by tkrussell
    Ok.

    Any generator system needs a transfer switch, either a manual unit or automatic.

    OK

    This isolates the utility line from the generator output, so the load only connects to either the utility or the generator, and there is no chance of the gen power getting out into the utility lines.

    OK

    Simply use a phase rotation instrument to check and note the rotation of utility lines and of the gen output at the transfer switch. if the gen output is different that the utility, simply switch any two wires of the gen output.

    OK I have read up on a phase rotation instrument, and I will be able to obtain one locally!

    Now the load will be fed by either the genset or utility with matching rotation, or sequence, of phases.
    Your information has helped me a great deal - thank you very much!! :) :) :)

Not your question? Ask your question View similar questions

 

Question Tools Search this Question
Search this Question:

Advanced Search

Add your answer here.


Check out some similar questions!

Can three single phase loads be driven individually by single three phase supply [ 2 Answers ]

Hi... I am new this community... You are doing great job of knowledge transfer... My question: Can three single phase loads be driven individually by single three phase supply? Please clear my doubt... :confused:

3 phase supply Vs 1Phase Supply [ 1 Answers ]

I wanted to know difference between 3 phase and 1 phase conceptually

How do you usually connect three single phase loads to a three phase generator? [ 2 Answers ]

How do you usually connect three single phase loads to a three phase electric generator?:)

Three phase generator [ 4 Answers ]

Dear Sir, If a three phase generator is loaded more on one phase and less on other does it effects is performance. At times a phase on generator runs overload while the other runs underload. What is the way to distribute the load equally on the three phases ? Please suggest. Regards, Nipun Jain

Running 220 single phase from generator? [ 1 Answers ]

I recently bought a wood planer. The id plate on the motor tells me it is 3 hp wired 220 single phase. The planer plug has three prongs on it. I plan to use this in my shop. My shop is powered with a 7000 watt generator. My generator has 220v but it has a 4 prong plug. CAn I change the plug on...


View more questions Search