Medium Voltage Power Supply Rack

6 Supplies; 24VDC to 400VDC Regulated Voltages:
The project was to gather up all the large power supplies laying around the lab, and have them all in one simple enclosure. Not only does this make it easier to use them, but it is safer because some do not have bottom or top enclosures and there is a significant shock hazard present. Or a tube could get broken, which would far worse!

Although the description shows using a sling to level the large units in the rack, any rack can be loaded up by laying it on its back and filling it, then tilting it upright, as long as there's enough oomph handy to do that safely. The borderline end-point for this business of 'Xtreme Racksports' starts when the rack-to-sportsman mass ratio gets to be much over 2:1 (assuming the classical mass distribution where weight is mostly towards the bottom of the rack and mostly around the middle of the sportsman.

Anyway, here's half a day's pleasant and healthy activity, which included troubleshooting two of the supplies.

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The lower rear section of the rack was filled with the two Sola 24VDC 25A fixed-voltage power supplies and the AC power distribution panel (bottom unit). They were put in the back to help balance the weight of the units to be put in the front. Since these 60-lb units are both shallow and not "box-shaped", the easiest way to install them was to lay the rack down, and place them on the rails, then install the screws, and set the rack upright. 		mvc-408f.jpg
The largest and heaviest power supply, rated 0 to 300VDC at a very solid 0.5A, with a respectable power to weight density of 1:1 (Watt/Lb.), was placed at the bottom. This beauty has seven 5U4 rectifiers and seven 6CD6's for pass tubes. In order to protect its front panel from careless feet, a 5.5" (4U) panel was placed in the lowest position, elevating the supply. The supply was set in place, and a sling made of a cargo strap was passed under it. 		mvc-409f.jpg
The sling was pulled to raise the unit to a level position. If the sling does not want to come along, the upward section can be pulled up to help raise the equipment to level. The top screws were started, and the bottom screws then put in and tightened to suck the panel up to the rack. During this process, it was useful to align the holes carefully using a thin screwdriver to adjust the clearance between the bottom of the power supply panel and the blank panel below it. The top screws were then tightened.
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All the supplies were mounted using blank panels between them for convection cooling where necessary. The 24VDC supplies in the back have no control panel utilities, so their outputs will be brought up to the front panel of the rack and terminals will be installed later. Power for the entire rack is controlled by the contactor in the power distribution panel, which was salvaged from a DEC computer rack. The contactor will be wired to the large switch at the top of the rack later. 		mvc-411f.jpg
The switch and its panel assembly were salvaged from a 1940's RCA broadcast system (which is a nice touch). This way, all the power can be controlled from the front of the rack. It is always important to have a main power shutoff on medium voltage and high voltage power supply equipment of any kind. The voltages from this system are certainly deadly.
The completed rack installation includes a formica top.

From top to bottom:
Main power switch and indicator lamp
0-300V 300mA regulated supply
0-100V 100mA regulated supply
0-400V 300mA regulated supply
0-300V 500mA regulated supply

The white 'notes' on the second and third power supplies are parts lists.. The 0-100V one was temporarily repaired, but the one below it needs a few more parts before firing it up. Keep in mind most of this equipment is about 40 years old.


KD5OEI