Wednesday, September 28, 2016

SSPA Power Supply - Load Test #6

Success!  Load test #6 is probably the final load test that I'll need to do with this power supply.  

I had no issues with the power supply.  The final protection diodes didn't get much hotter than 95F during this test of 62 amps @ 53 vdc.  In the last test I measured peaks around 180F.  So my junk-pile heat sinks and muffin fans cut their temps about in half.  

This test proved that my fixes for:


  • The high temps on the final diodes reduced to 95F which is 50% lower than what they were at, and only 33% of their max temp spec.  Plenty of headroom there now.
  • The new contactor and time-delay resolved sporadic initial startup and immediate power down of random supplies (safe mode due to surge).
  • Replacement of the 400A shunt with a 150A shunt resolved the low amp reading on the 150A meter (doh!).  I'd read that I should overrate the shunt for safety, that proved to be incorrect.  The ammeter now reads accurately.
  • The voltage monitors work in-circuit now.  If voltage is below or above range, the final contactor is forced open.
The only issues I had with this test was that the wires (#14 ga) on the Load Tester elements (and not the power supply being tested) started to get too hot after about 6 minutes of testing.  THAT is acceptable for now :-)   But I'll get some #10 for the future I think.  Maybe even #8 for safety.  If those wires had melted through I'd have had a fire hazard.

Fairly LONG demo video (not real stable if you get sea sick take your meds now LOL).