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Joined: 05/06/2004
Location: AustraliaPosts: 5189
| Posted: 08:11am 21 May 2011 |
I've come up with a usefull first project for the Maximite, a RPM to Watt plotter.
One of the most difficult things to do is plot the power to RPM curve for a alternator. Normally, you would bolt the alternator into a large lathe, bring it up to speed and measure the watts at that speed, with the output connected to a battery or dump load. Its a painfull process because most lathe's dont have much in the range of speeds to choose from, and you need to measure the amps and watts at each RPM, which takes time. A lathe is used because it will keep the alternator at a constant speed, giving you time to measure the amps and volts.
The Maximite is very fast at reading its analogue/digital inputs, and can process that data within a few milliseconds. It can take hundreds of readings per second. If we connect up volt, current and RPM sensors to the Maximite, it could plot a power curve, very quickly, in one session. For smaller alternators, like the F&P, a variable speed electric drill will work, just bring the alternator up to max speed in a few seconds, you have a power curve on the screen! Larger alternators need more power, and even most lathes struggle to turn a 1 to 5 kw alternator at full power, so you could use a petrol motor and clutch, or even a car ( seen it done! ) to drive the alternator up to full speed over a couple of seconds while the Maximite plots the power curve.
You could also add an efficiency curve, done with a pony brake and a pressure sensor. A strain guage from a set of electronic scales could be adapted.
The data can be saved to the SD card as a Excel file. I'll see what I can put together this week.
Glenn
The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ