Automatic voltage regulator for a tap transformer

Discussion in 'The Projects Forum' started by ssembo, Jan 10, 2011.

  1. ssembo

    Thread Starter Member

    Dec 13, 2010
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    Hello guys, i want to design an electronic circuit to regulate 132kV nominal primary voltage with range +/-1.31% and output a 33kV. This has to done using a tap changer motor. I want to develop a circuit that can control this motor by changing the direction of the motor. Am not good at electronics. thanks
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,795
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    33,000 Volts

    :eek:


    I know electronics well enough to know I wouldn't get within 10 feet of that voltage. If you know very little, I would suggest you forgoe the possible electrocution and let someone who is familiar with that kind of power circuit do the work.
     
  3. Ctenom

    Member

    Nov 1, 2010
    59
    1
    I think he is referring to the motor speed. Kv = RPM / (Vin - Vloss) I think
     
  4. debe

    Well-Known Member

    Sep 21, 2010
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    Is this just a design project? Ive seen 33Kv transformers years ago when i worked for ETSA that were auto taping on the primary for voltage regulation, these were huge!
     
  5. ssembo

    Thread Starter Member

    Dec 13, 2010
    35
    0
    Hello, i request you to help me on making an automatic voltage regulator for a tap transformer. 3 phase, 20MVA, 132kV being on nominal tap 4 and a constant output of 33kV. the range of input voltages is +/-1.31% for the 17 tap positions. need to make a voltage regulator to control the motor driven variac that changes the taps.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Since these threads were on the same topic, I have merged them.

    I am not a power engineering type, but I thought a variac was an autotransformer.
     
  7. #12

    Expert

    Nov 30, 2010
    16,346
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    Anyone here qualified to design parts for a 20MVA power station without ever seeing it?
     
  8. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,795
    951
    Search Google for High voltage workers, and try to find a forum with people who work with this type of equipment, the equipment is common enough, but this is a small group of people that work with and understand the procedures. I may be wrong, but even with our large membership, I doubt we have more than 2 or 3 here, who have ever worked with it, and zero is more likely in my opinion. Finding one of them online at the right time to help. ??

    Search google somemore, its out there.
     
  9. ssembo

    Thread Starter Member

    Dec 13, 2010
    35
    0
    Guys usually, the 132/33kV voltage exists at transmission substations...atleast thats what happens here. This high voltage is usually steped down to 110V and this is what is used for control. The variac is a 3 phase synchronous motor and either moves up or down the taps depending on the input voltage. The circuit i want to design is to detect a change in secondary voltage of the transformer and make sure that it changes the taps to maintain the secondary at 33kV.

    Please, don't loose hope. Lets do this togethr=er cause i need your help.

    Thanks

    Colin
     
  10. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    4,887
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    Reminds me of the time my boss asked me to connect a sensor into a campus substation. Big fence, big red signs with lightening bolts on them. You could just hear the thing humming (and before you ask I did not recognize the song :) ). I took one look at him and told him that he could go hook the thing up. :)

    This post sounds suspiciously like homework to me. Something that won't be built just designed.
     
  11. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    There are two issues here.

    1. Detecting secondary voltage against setpoint and issues tap change command(up/down) to hold the secondary voltage at the required level.

    2. Tap change motor control circuit via relays and limit switches such that the command in step 1 can be carried out.

    The whole set up is known as the "Automatic Tap changer". Which part of the above would you like to know?

    I stressed "know" because you should not be building one if you haven't got the required knowledge to do so.

    On load tap changing operation is a high energy process and causes stress on the apparatus so is only carried out unless it is absolutely necessory.
     
  12. ssembo

    Thread Starter Member

    Dec 13, 2010
    35
    0
    i would like to know the first and the bit of relay. Thanks for the hope given.

    Colin
     
  13. ssembo

    Thread Starter Member

    Dec 13, 2010
    35
    0
    i would like to know about the first and the bit of relay. Thanks for the hope given.

    Colin
     
  14. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    The tap changer relay is a very complex relay which take in three phase voltage and current signals. It then works out the power factor and MVA loading of the transformer. It also check if the present voltage is stable and not a sudden dip or rise due to loading change.

    Only then it can decide if a tap changing operation is required to maintain the secondary line voltage.

    Those relays are expensive and come from reputable manufacturers. Never know of any case of people/utility of using one build as DIY on transformers in the MVA range.

    The following one will give you some indication of what functions are required if you try to build one.

    tap changer relay
     
    Last edited: Jan 13, 2011
  15. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,699
    907
    Have our rules about helping someone kill himself or others changed?

    "Thanks" just doesn't seem to be adequate.

    John
     
  16. ssembo

    Thread Starter Member

    Dec 13, 2010
    35
    0
    This seems to be a rather complicated idea, can you guys help me with design project ideas? I really need a project for my final year, deadline way too near. I am pursuing a degree in electrical engineering. I would like something to deal with power systems control or equipment. Thanks
     
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