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Unread 19-09-2014, 23:41
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Re: 2015 Beta Testing - The Components are Here.

Quote:
Originally Posted by compwiztobe View Post
Not sure what stage you're at in the test right now, but I think many people would be interested in data regarding compressor current draw vs. time and pressure, if you can fit it in. EDIT: I should clarify: since this will depend a lot on the exact compressor model, maybe compare it to the current draw when running off a spike using pre-2015 control logic (hard starts), so we can see how the PCM manages the current draw.
There's no difference in the performance of a compressor under the old control system vs. the new control system.
The only difference between systems is how they react to problems.
If the compressor is too large and tries to pull too much current for too long, the old system would trip a self-resetting breaker for longer and longer periods as it heated up, while the new system would react much faster and immediately cut power for a second, try again, cut power, etc.

Here's a plot of the current draw of an old KOP Thomas compressor filling one storage tank. There is a momentary spike when the motor is starting (locked rotor) of ~36a for a fraction of a second, then it drops way down before starting a climb as the pressure in the tank increases.

A ViAir 90C compressor draws much less current, but takes longer to fill the same small volume. The difference is more noticeable with more storage tanks.

This test was done with the new control system on an older robot that didn't have a pressure transducer to record the corresponding pressure. The same test on an older control system looks identical. Somewhere I've got time vs pressure graphs from tests we ran for these two models- here's a post comparing them.
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Last edited by Mark McLeod : 20-09-2014 at 08:38.
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