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Re: Measuring a Motor

Subject: Re: Measuring a Motor
From: Jamie
Date: Sun, 20 Aug 2006 19:15:45 -0700
Newsgroups: sci.electronics.basics
Greg Hansen wrote:

Can you tell, by measuring things like voltage across a motor or the current it draws, how hard it's working and whether there's a sudden resistance to it?

The Minneapolis library has a new building which, to make more efficient use of space, has motorized stacks that move when a butten is pressed to make room for a user to browse books. They have an optical system for checking obstructions, which has something to do with bouncing a moving laser beam from mirrors near the floor. But there were some problems with it after it was installed. Sometimes it said there was an obstruction when none was there. And at least one time it moved the stacks when there was an obstruction, crushing a sturdy metal foot stool in the process. That's kind of scary.

So I thought there could, and should, be a system that monitors the motors directly to say "The resistance suddenly and unexpectedly increased-- stop now and back off!"

I don't know if they're AC or DC motors.

I think I prefer the hand-cranked stacks that I saw at a national lab.
yes, Current transformers wired into a sensing board can be made to
shift the motor in reverse direction or shut it off.

Real Programmers Do things like this.

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