Author Topic: Coil Options  (Read 462 times)

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tooseevee

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Reply #15 on: March 27, 2021, 10:25:47 am
I'm not finding anything that tells me this isn't an oil-filled coil. IF IT IS, it won't like being upside down. The oil is an insulating as well as cooling medium, and the windings that were at the bottom covered up with oil will now be exposed. They will not be cooled and the insulation factor is reduced.

A "potted" coil (epoxy or other solid) doesn't care about orientation, but on the Summit speed part site most of the coils are oil filled, even the pricey ones. Check with Bosch before putting your $50 coil upside down.

          Just curious: Why would an oil-filled coil be only partly filled?

           I don't recall ever hearing warnings about never mounting coils upside down.
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AzCal Retred

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Reply #16 on: March 27, 2021, 03:21:03 pm
The air space is for expansion when the oil gets warm or hot, a solidly oil filled case would hydraulic the top off. There is no way to know exactly how much airspace exists inside without taking it apart. Normally on oil cooled apparatus the expansion space is engineered to keep the expected pressure values low enough to not challenge the seals under predicted conditions. The expectation is that they will be mounted near vertical, so the windings are low in the case so as to be kept covered. The oil is both insulator & cooling medium. A lack of oil reduces the winding/case insulating magnitudes and decreases cooling ability for the winding area exposed.

Potted (amazingly like tar...)  or epoxy filled windings generally have larger cases to produce greater surface area for cooling, as the heat transfer is via conduction, not convection. Unlike conduction, convection physically allows warm fluid to move, carrying away heat. Potted windings are very vibration resistant as the wire within is entirely surrounded & supported, not just suspended in a can of oil. Both can work well in proper application.

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AzCal Retred

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Reply #17 on: March 28, 2021, 10:23:43 pm
A brace of 1999 Bullets: 1 Red Deluxe, 1 Green Standard. Also, 1 wee orphan 1956 Fire Arrow project.


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Reply #18 on: April 02, 2021, 06:37:46 am
I do like that second one you have listed.