Physical Size and Weight

A basic measure of any power supply is the unit’s overall physical size and weight.  This may seem rather simplistic but it generally holds that more industrial grade components and larger heatsinks equal a better PSU.  

So – this almost seems unfair.  The Miller XMT 300 PC power supply measures: 12.5” x 17” x 24” (W x H x D) and weighs 80 lbs! The following graph illustrates how the weight of the Miller PSU compares to some other popular power supplies on the market.

DC Output Load Regulation

Of course one of the first things we want to see is how well a PSU can regulate the DC outputs and maintain rock-solid voltages.  To simulate real world loading conditions, the big Miller PSU was connected to everything I had available except for the basement sink and supplied with 240 VAC.  

In this test we are interested in seeing how well a PSU can maintain the various output voltages while operating under different loads.  The new ATX12V V2.2 tolerance for voltages states how much each output (rail) is allowed to fluctuate and has tighter tolerances now for the +12V outputs.  

The following table lists the DC voltage results at the different loads for the Miller XMT 300 PC PSU while operating on 240 VAC, 60 Hz.

Up until one of the resistive load banks overheated and caught fire during test #7, the PSU produced stellar load regulation on all of the outputs across a broad range of loads; even when delivering 2,500 watts of DC power.  

Oh @#$%!  That’s not good!  Fire-Fire-Fire!  Well, turn it off, turn it off!  These are a few of the thoughts that flashed thru my mind as I reached for the fire extinguisher…

Unfortunately, that concluded our testing on the Miller XMT 300 PC power supply…

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