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Gemini 060615 released!
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| | | |-+  ECS/EPS Documentation (and testing)
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Author Topic: ECS/EPS Documentation (and testing)  (Read 1830 times)
Tschachim
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« on: December 19, 2006, 11:33:40 AM »

I've revised the EPS documentation (http://nassp.sf.net/wiki/Electrical_Power_System_%28CSM%29) so that the procedures mentioned there are working again. Also I enhanced the ProjectApolloMFD a little bit so that you can provide test heating/cooling to the coolant loops with it (instead of the HIGH GAIN ANTENNA PITCH POSITION switch). With that the ECS procedures (http://nassp.sf.net/wiki/Environmental_Control_System_%28CSM%29) will be working again, I'm going to change them soon and explain how to test the ECS with the ProjectApolloMFD.

Both the EPS and the ECS articles contain just a few procedures, no reference information nor panel explanations. Almostfm, you mentioned you're working on some documentation about that. It would be great if we can use that in the wiki, too! Happy If you (or someone else) want to work on that, please post here, otherwise I'll have to do that sooner or later... Wink

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Tschachim
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dseagrav
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« Reply #1 on: January 14, 2007, 08:12:23 AM »

I redid the AC bus feed and inverter. The inverter now varies in efficiency according to load power and input voltage. (Load reactance is not modeled.) I match NASA's load curves for the inverter to a few percent, I think. Also, the AC busses are now 3-phase all the way to the inverter.

The input links for the AC busses were deleted and replaced with switches that emulate the motor-switch network the CM used. Inverter 1 overrides 2, 2 overrides 3, and 3 overrides 1. That is, switching on inverter 3 will deactivate inverter 1, but switching on inverter 2 will not deactivate inverter 1. Inverter 2 will take the load immediately if inverter 1 is switched off while it is switched on. One inverter can feed both AC busses but only one inverter can feed a bus at a time.

Inverter overload and its associated C/WS alarm are now detected. Overload doesn't disconnect the inverter, All-phases-overload is alarmed 5 seconds faster than spec, but it probably doesn't matter. (Single-phase-overload alarms in 5 seconds, all-phases-overload is supposed to alarm after 15 +/- 5. In our case both are alarmed if persisted for 5 seconds.)
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Tschachim
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« Reply #2 on: January 14, 2007, 09:06:01 AM »

Cool, thanks a lot for doing that! Happy
Is it possible now to actually overload an inverter?

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Tschachim
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dseagrav
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« Reply #3 on: January 14, 2007, 09:29:39 AM »

I don't think we have enough AC stuff yet to do it; The highest I could get was around 8 amps by stuffing everything I could find on AC1. I did test the overload logic by setting the threshold low, and it worked. I ran out of DC amps first (or at least put enough stuff on MNA to cause the fuel cells to disconnect. I had 62 amps or so.) but I had pretty much everything I could find turned on to make sure nothing blew out. To overload we have to get to 27.7 amps all-phases or 11 amps on a single phase.

I was surprised at how inefficient the inverter is supposed to be. The load chart has it as low as 55% toward the edges of its operation. It peaks out around 77% efficient at 650 watts load. I wonder if the heat dissipated from all that efficiency was the real limiting factor?
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