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Isolating transformer help

MrJack96
fbfff694442d96ab55a4ca1cf11d99ce-huge-2f44b3c6-e82b-49a0-b1bd-1df87196400c.jpg36db8eb65df624d194c4f0d38bc9d37e-huge-858d560a-6a7b-4127-9383-db090315f918.jpg5829e0bca8ccbe2f8ca57ff4780fc9b2-huge-19d0edbf-ea01-407a-9fc4-6ac2c9c6ba51.jpgHi guys I have seen an isolating transformer feeding a single phase pump on site and am unsure if it should be isolated. I can see they have tied the 0v on the 110v side to earth just not the 240v Can anyone give me some advice. Here are some pictures. 


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  • 0
    What I'd expect,

    1) the primary winding to be the 240V side, wired accross L and N. (N is also connected to E of course, but back at the source not there) If you put a meter between each end of the winding and ground in turn you would hope to see 240V on one and very little on the other..


    2) The secondary winding has 110V accross it and supplies the pump, and one side is tied to earth and we can call this the 110V pseudo-neutral, and the other side the 110V pseudo live. These have no direct connection to the incoming mains live and neutral - it is an isolation transformer after all, but If you put a meter between each end of the winding and ground in turn you would see 110V or so on one side and very little on the other. (and of course 110V across the 110v load as well...)



    If its not that, then if you could describe in more detail what is there that may help.



    PS staring at the photo, that transformer seems to have more than 2 windings- are the two top windings primaries and the lower ones isolated secondaries ?



    M.
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  • 0
    What I'd expect,

    1) the primary winding to be the 240V side, wired accross L and N. (N is also connected to E of course, but back at the source not there) If you put a meter between each end of the winding and ground in turn you would hope to see 240V on one and very little on the other..


    2) The secondary winding has 110V accross it and supplies the pump, and one side is tied to earth and we can call this the 110V pseudo-neutral, and the other side the 110V pseudo live. These have no direct connection to the incoming mains live and neutral - it is an isolation transformer after all, but If you put a meter between each end of the winding and ground in turn you would see 110V or so on one side and very little on the other. (and of course 110V across the 110v load as well...)



    If its not that, then if you could describe in more detail what is there that may help.



    PS staring at the photo, that transformer seems to have more than 2 windings- are the two top windings primaries and the lower ones isolated secondaries ?



    M.
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