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  1. bigmantony

    Transformer Time Constant

    Dear Xfmrexpert, thanks for your response. Apologise for being rather vague. Its not the thermal time constant I was referring to but the Rated Secondary Loop Time Constant (Ts) as referred to in 60044-6 para 3.14 Do you know of a simple test method for calculating this value?
  2. bigmantony

    Transformer Time Constant

    Does anyone know of a simple method for measuring the Transformer Time Constant?
  3. bigmantony

    Lead Free Solder

    Dear Vladpl, Getting back on track to your initial question. We tried Multicole Solder (for hand soldering) 96SC Crystal 511 96SC Ersin 309 We preferred the 96SC Ersin 309. In the UK I contacted the multicore tech help: Ian.Williams@uk.henkel.com He will help you find a source in the Great...
  4. bigmantony

    CT Remanence Measurement

    It touching that so many of you are concerned for my well-being and staying alive. The evils of open cct CT's has drifted slightly from the thread. Remanence is a test our customer wants us provide for certain CT's. Gapped cores (oh joy!) I have carried out the test in the past using a digital...
  5. bigmantony

    CT Remanence Measurement

    Dear Engineers, Does any know of, or have, any equipment that measures the Remanence of CT's?
  6. bigmantony

    40,000A Current Supply

    Hi DJS, these spot welding transformers are good for quick bursts of current but alas we require something more continuous. Cheers anyway. For those interested in this thread, we came up with the idea of putting evenly spaced Taps throughout the winding and testing section at a time at lower...
  7. bigmantony

    40,000A Current Supply

    Thank you all for your kind responses. We shall review them just now. Its an AC transformer, it will have screen windings, and require to meet BSEN/IEC6044-1. We require a continuous supply as we have to show that it meets the ratio error limits. ScottyUK - BSTS is a skeleton of its former...
  8. bigmantony

    Sizing Core Balance CT's

    1. Determine Primary Operating Current,POC, (earth fault tripping current.) 2. Select an appropriate earth fault sensing relay, either 1A or 5A. 3. From above info, the CT ratio can be defined eg. assume 1A relay and assume POC 2A if relay set for 10% tripping (of 1A) then CT ratio to be 20:1...
  9. bigmantony

    40,000A Current Supply

    I require to design a current tranformer for use with a primary current of 40,000A (forty thousand) Problem: getting a supply to test the bugger! Does anyone know of a test house or supply (preferably UK) that can generate 40,000A for me? Looping a primary conductor many times around the CT...
  10. bigmantony

    DC Current Transformers

    Just returned to site. A big thankyou to all and I shall review everyones comments and responed with any questions that i may have. Tony
  11. bigmantony

    DC Current Transformers

    Dear All, does anyone have technical knowledge of DC Current transformers. So far have not found any useful info on the web. Also, does anyone know of manufacturers of these units. Looking forward to responses.
  12. bigmantony

    Rain Spray Testing

    TMD has hit the nail on the head. Thanks to everyone for their input, So what have I done to resolve my issue. Well, I placed my unit over a bucket and sprayed it with as fine a spray as I could get from a Homebase Hose and measured the water level after 1hr. It measured 4 inches. I repeated...
  13. bigmantony

    Rain Spray Testing

    Thanks to all for your help. I am working thru the info. For Cuky2000, we have an IP67 terminal box that will be subjected to all weather conditions and our customer wishes to see that it meets the 1 inch/hr for 2 hrs. We were hoping to attempt the set-up of this test in-house.
  14. bigmantony

    Rain Spray Testing

    Does anyone out there have knowledge and tips on how to create and measure a Rain Spray Test. Our aim is to subject our unit to 1 inch of rain/hour for 2 hrs. How is an inch of rain defined (ie. is there a defined surafce area in which to hold an inch? Is there a droplet size to maintain?) and...
  15. bigmantony

    CT secondary load and tolerance

    The standard does state the CT should maintain accuracy with 25% to 100% rated current. Engineers usually allow greater loadings than required when sizing the CT. CT manufacturers compensate the turns of the CT to meet the current error but if they compensate by more than the CT accuracy class...
  16. bigmantony

    Remanace Calculations

    Our Aim: to measure remanace on a Current Transformer using basic circuit components. I know there are expensive scopes that can help but I would like to get a more hands on approach. Does anyone have any thoughts and information on this subject? There are a lot of descriptions for remanance...

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