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  1. Millbo

    References for Typical ANSI Standard Power Device Functions?

    Refer to IEEE C37.2 - Standard for Electrical Power System Device Function Numbers, Acronyms, and Contact Designations
  2. Millbo

    Forces on DS terminals in HV substations

    I think "cross load" is lateral load.
  3. Millbo

    IEEE 43-2000 Theory applied to XFMRS

    SCERS, The Megger publication, A stitch in Time" states the following: "...Acceptable insulation resistance values for dry and compound-filled transformers should be comparable to those for Class A rotating machinery, although no standard minimum values are available...." IEEE Standard 43...
  4. Millbo

    Storing Power Transformer as Spare

    The manufacturers O&M manual will give guidance on putting their units in long term storage. A few key things from memory: Keep the bushings/windings shorted and grounded If it's a conservator type unit keep up with the condition of the desiccant in its breather Power up the heaters in the...
  5. Millbo

    Transformer Lifting Technologies

    Often due to head room and load weight most rigging contractors will use what's call "Jack & Slide" to move a load. This is where they will jack it up high enough to put rails under it then they will push it along those rails with hydraulic jacks. The better systems have catch pawls that the...
  6. Millbo

    Help needed û Adjustable constant AC current source: a viable circuit or a valid equipment supplier

    Thanks itsmoked. So does this mean its a modified wave signal?
  7. Millbo

    Help needed û Adjustable constant AC current source: a viable circuit or a valid equipment supplier

    VE1BLL, That current source sounds like it will fit the bill. I'll send them an email for some additional information. I appreciate the link and the leg work on this one, Mike Also, I also ran across a company called Lectrotek out of India. http://lectrotek.com They carry a device called...
  8. Millbo

    Help needed û Adjustable constant AC current source: a viable circuit or a valid equipment supplier

    This will need to be something that is both rugged and can survive field conditions. They will be hauled around in our test trucks with the other test equipment. I've exhausted every avenue I can think of. Thanks all and have a great holiday weekend, Mike
  9. Millbo

    Help needed û Adjustable constant AC current source: a viable circuit or a valid equipment supplier

    electricpete, A secondary current injection set is what I use to apply my test current to the circuit in my first reply. I remove the CT from the circuit and am just simulating the secondary of that CT as if the transformer was at full load. I chose to use these injection sets being they...
  10. Millbo

    Help needed û Adjustable constant AC current source: a viable circuit or a valid equipment supplier

    VE1BLL Thanks for the replay but I may have been a little vauge in my initial post. The bushing CT that I'm simulating the secondary current for is installed inside the transformer and I don't really need access to it. I'm just simulating it's output current. To perform the commissioning test I...
  11. Millbo

    Tranformer assessment and Life extension

    I also agree with ppedUK and jkristinn How sudden did this condition come on? Are loads and temperatures logged on a regular basis? These values will allow you to plot out any trends. One suggestion I have it to look at your cooling system thru an IR camera while the unit is loaded and check...
  12. Millbo

    Help needed û Adjustable constant AC current source: a viable circuit or a valid equipment supplier

    I have a question or perhaps more of request for information and or suggestions please from those who know electronics more than I do. My Issue at hand: I need an adjustable constant AC current source to simulate the secondary of an energized hotspot CT to verify the winding temperature...
  13. Millbo

    transformer oil treatment plant

    I'm partial to the Baron units. We have eight of their HV-1800 models and their performance is great.
  14. Millbo

    Power Transformer Excitation Current

    The wrong test connections were used according to the transformers nameplate. Per the phasor diagram the test connections should have been: H1 - H3 = A phase H2 - H1 = B phase H3 - H2 = C phase The contractor followed the standard Doble template with those connection resulting in: H1 - H2...
  15. Millbo

    Core Ground Bushings on Top of Transformer?

    1. I also agree with the general consensus. "Megger" that one floating bushing against ground to see what it's value is. Any Core ground or Frame (clamp) ground that is brought out should go to earth. If it was left open due to an inadvertent ground then that bushing should still go to...
  16. Millbo

    Paper by R.E. Uptegraff concerning gassing due to core ground connection location.

    Gentlemen, Do any of you recall a paper put out by Mr. R. E. Uptegraff back in the late 70's or early 80's concerning the source of gassing in small distribution type units being related to the location of the core ground connection. He was very active in the IEEE during these years. He also...
  17. Millbo

    Counter reading of LA

    RAgrawal, It wouldn't hurt to test your arrestors if your taking your system down. Compare the watts losses of each like arrestor. Eeach section should be tested if they're multi-stack. I can't speak on the harmonics. Hope you get this resolved, Mike
  18. Millbo

    CT Testing and Connections

    Nathan, Is this a new install? If so does your input current suddenly spike as your ramping up? I've had a bushing CT do this to me and come to find out that one the bare ring terminals on the backside of the barrier board was pressed against the adjecent wire. It wasn't metal to metal contact...
  19. Millbo

    Transformer Nameplate Information

    pwrshl C57.12.00-2000, 5.12.2 Nameplate information. States "...Unless otherwise specified, the minimum information shown on the nameplate shall be..." Serial number Month/year of manufacture Class (ONAN, ONAF, etc.) Number of phases Frequency kVA (or MVA) rating Voltage ratings Tap voltages...
  20. Millbo

    SHUNT REACTOr

    pie314 I deal with transformer manufacturers from other countries. They use MT for medium tension aka medium voltage.

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