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View Diary: The simple innovation that could make wind power a big player (230 comments)

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  •  And some transformer standards are built around (1+ / 0-)
    Recommended by:
    jam

    a concept that if you use the transformer within its ratings, 100 per cent of the time, you can expect some figure, X hours, frequently I have seen the number 20,000 hours as the expected life.  So, if you run it above its ratings, then that number 20,000 hours may be expected to drop to maybe 19,000 hours if the temperature excursion is defined and predictable.

    Design activity may be undertaken to account for temperature excursions as well.  If for instance the insulation system rating is 180 Deg C, and the excursions would dictate a rating of 220 Deg C, then the act of purchasing the 220 Deg C insulation system may be a low cost alternative to a bigger transformer.  You are sized for 95 per cent of usage, with capability to handle a larger load 5 per cent of the time, without degradation of the expected life of the transformer.

    On the example of cool the cord, in my opinion, I believe a better, more reliable solution is to purchase a cord or cable with a higher temperature rating, for instance, replacing a 90 deg C wire with 105 or 130 Deg C wire which has higher ampacity in the first place and can take the higher operating temperature, which of course is a fire risk if the wire is used in excess of its capacity.  I have long experience in the electrical safety business, and if you submitted that kind of arrangement to a certification lab, it would be rejected out of hand.

    Alternately, if short term current excursions were expected, you could put a duty cycle rating on it  to cover for the excursion, but duty cycles are cumbersome and some consumers would ignore them, leading to a fire or electrical shock risk.

    Republicans are like alligators. All mouth and no ears.

    by Ohiodem1 on Wed Jan 23, 2013 at 08:06:44 AM PST

    [ Parent ]

    •  that was the other thing (0+ / 0-)

      temperature, I forgot. The highest winds (at this location) were only during the winter with ambient temps usually around 0-10 C. And the transformer we put in is ONAN. If temperature became a problem, they could always slap a couple of pumps on it to become OFAF, right?

      Ultimately, I'm not a transformer guy, I'm a little wires guy.

      Javelin, Jockey details, all posts, discontinue

      by jam on Wed Jan 23, 2013 at 08:27:24 AM PST

      [ Parent ]

    •  The cord cooling approach is actually being used.. (0+ / 0-)

      because realistically you need an order of magnitude or so better cooling than passive air cooling alone can provide, not something that a mere uprating of wire type or insulation can provide.  Rapid charging can be hundreds of amps for 5-15 minutes; the tables for passive air cooled steady-state wires state something like 0.5-1" diameter, give or take depending on the details - way too heavy and cumbersome.

      I don't know what sort of coolant they use, but I would expect that it is relatively nonconductive and non-flammable.  

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