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Continuos Winding Monitoring

  1. Jul 18, 2012 #1
    Does anybody know if exist a kind of Insulation Monitoring Relay, to be Online (energized) all the time and be able to monitor the Transformers and Motors Winding continuously?
     
  2. jcsd
  3. Jul 18, 2012 #2

    jim hardy

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    How big are the machines?
    What condition are you tying to detect?

    In our central station generators(894 MVA) we monitored temperature rise of hydrogen in each conductor(looking for uneven rise indicative of broken strands)
    and RF noise in the neutral lead(indicative of arcing).

    old jim
     
  4. Jul 18, 2012 #3
    Good day Jim, thanks for your answer.
    Basically I am in the range of 20 MVA Transformers and perhaps 15 MVA Motors, up to 35KV.
    I was told there could be online winding insulation monitoring relays, that would check if the Motor or Transformer insulation is leaking current to ground, with the machine energized...
    Have you heard about it? Any ABB or AEG or Siemens new relay in the market?
    Thanks
     
  5. Jul 19, 2012 #4

    jim hardy

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    haven't done much since early days when they brought in sophisticated equipment to monitor power leads with RF current transformers.

    What works nearly as well is an inexpensive transistor radio set on AM band between stations. If a machine has insulation trouble there'll be corona and the radio will tell you. The sophisticated equipment puts a number on it for you.
    You can do very well with the radio and periodic walkdowns of your plant , you'll get to know each machine's "voice" and how it varies with weather. That's what i did. But continuous monitoring would be better.

    We used clamp-around RF transformer on generator neutral and a specialized Westinghouse relay which was just an RF voltmeter. One plant in Missouri used same transformer with a Hewlett-Packard tuneable RF voltmeter to get away from interfering local AM broadcast stations operating near the frequency of interest, ~ 1mhz.

    honestly i haven't been into this in decades now and I think you'd get better information from them , or one of the small creative companies. Google search on PD monitor turned up scores of them. http://www.irispower.com/motor_cm_pdtrac.aspx et al

    At an industry conference about 1981 i saw a presentation by one utility fellow who used his isophase standoffs as capacitive couplers, just put a insulated plate under the foot and ran a co-ax cable into an RF analyser. It picked up the RF from partial discharge. Now i see such systems on the market from almost everybody.
    http://www.doble.com/products/partial_discharge_detection.html
    http://static.schneider-electric.us/docs/Electrical Distribution/Services/1910HO0920.pdf

    Sorry but i just dont have hands-on experience with the new monitors.

    The science seems to have matured considerably since my time.
    http://www.siemens.co.uk/pool/energy/uhf_pdm.pdf

    Wow !

    old jim
     
    Last edited: Jul 19, 2012
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