Greetings,
I've been working on the rectifier box for our new axial. I'm getting ready to do final mounts and wiring. I thought it would be a good time to gather comments before I do.
There are heatsinks on both the front sides and ends of the enclosure. The rpm gauge is mounted on the front 1-5 VDC coresponding to 100-500 rpm. The center panel hinges from the top down to allow access to the turbine-side (50A 300V) breakers, and the Omron sensing relay. The rpm board is mounted on the inside of the center panel. Here it is mostly, loosely, assembled:
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To access the diodes and wiring terminals I've hinged the front sinks. Thumb screws secure them closed, but each pair is somewhat isolated from the metal portion of the box due to the anodizing and nylon shoulder washers and stops. I'm not sure that this is critical, but Jim (Sencenbaugh) had suggested that the hard anodizing provided a shock barrier if the heat sinks were touched in a ground fault scenario.
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Basically there are two sets of (6) diodes, each providing an isol;ated input to one of the two Classics CC. The diodes are stud mounted in aluminum blocks - just one set of three is installed in the photos. The blocks will be electrically separated from the heatsinks by sil-pads, and are connected to the sinks with nylon screws:
http://www.farnell.com/datasheets/313126.pdfAlso mounted on the side heatsinks are two SS relays. One is for our load diversion, or clipper and will be controlled by the Aux 1 output of the Classic. The second is a hi-voltage limit diconnect, which I hope never has to opperate. This was a scheme presented here by Rob Beckers. The dump will be paired with the upper range CC, which overall I expect will be dissapating considerabley less heat.
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I would appreciate comments, and I have a few questions:
Is it recomended to also use thermal grease with the sil-pad?
How much overlap, or extention of the mmaterial should there be beyond the diode blocks?
Should the sil-pad be used under the relays as well (I think I have enough)?
Thanks for any input.
~kitestrings