Training course on transformers and three phase supply

Good morning all,

I'm looking for recommendations on a training course in three phase supply, types of transformers and their safety and testing. I've got a good basic knowledge of the types of transformers but I am conscious that a gap in my knowledge is the differences between them and the safety implications of using the different types. Apologies this is a bit vague but I'm not really sure what else to ask! Any recommendations would be extremely helpful.

Thanks in advance!


  • I presume this relates to your other query, and the transformers in question are LV units, not the sort of thing that is found as part of HV distribution ?

    I am not aware of a transformer course as such (someone somewhere will no doubt run one though) but it may be useful to define better what you feel you do not know but need to. Are you looking at transformers driven from variable frequency supplies, current transformers for signal monitoring, or mainly just power supplies requiring a voltage conversion.

    I can imagine odd voltages on fair ground kit, and a mix of AC and DC motors.

    The degree of isolation required between a transformer and its windings depend on the voltage of course, but also on the earthing strategy, and what happens if it fails. There will also be situations where the correct behaviour is not immediate ADS, but to keep power on until a safe stop.

    Testing will generally be looking for winding to winding shorts, or winding to core shorts (DC resistance tests at appropriate voltages) or shorted turns ( if there is too much unloaded primary current and or an excessive temperature rise)

    This is not just wiring related regs but also machinery regulations and probably very specific rules for some types of equipment. (overhead feed 'dodgem' cars come to mind of which there are several flavours.)


  • Hi M, it is kind of related to my previous question but more related to the HV side as basically I came across an installation that was a Delta Delta transformer output from the substation and it occurs to me that I'm not totally sure what the pros and cons of different types of HV transformer supply outputs would be and where they should and shouldn't be used? The short answer is I'm not really sure what I don't know so your response has already been helpful!

    We certainly see odd voltages, travelling and fixed types of supply, AC and DC.... We work on new and historic kit so I see a bit of everything!


  • In the UK the substations are normally delta on the high side and star on the secondary (sometimes indicated by Dy - the big letter for the bigger voltage.) There may be a 'clocking number' to indicate the phase shift.

    e.g.the commmon Dyn 11 means that the voltage of the secondary star winding leads the primary phase voltage by 30 degrees and it corresponds to "11 o'clock."

    rather more than you probably want on that here

    If you have a delta winding you do not have a place to call 'neutral' unless you create it specially with a star of identical impedance.

    Neutral does not have to be in the middle of the 3 phases.... Some American designs ground mid point of the side of a delta, so the three phase voltages are now NOT equal relative to ground (but have equal voltages relative to each other of course.) more on that here



  • Brilliant this is the kind of info that I needed so thank you

  • I went on a good 2 day introductory course to three phase this week. I enjoyed it; 

    They didn't cover transformers just the distribution box to the end device.