Andrew P. Lentvorski, Jr. wrote:
On Feb 20, 2005, at 4:39 PM, Paul G. Allen wrote:
If you wanted to cut current from the source and monitor this, you could (not that this is what the device is doing). Any coil (including those in motors) will induce current in wires connected to it /after/ it's current source has been disconnected, or if a magnetic field is passed near it. Cut the source current, and the motor becomes a sort of generator (alternator for AC motors) and a detector on the source wires can measure the speed at which it's turning, or if it's turning at all.
And it will induce a current *why*?
Most industrial and consumer motors do not have permanent magnets. In that case, a turned motor will *not* induce a returned current as there is no magnetic field to provide a change in flux.
Before continuing to speculate on electricity, please go read a basic electromagnetics textbook.
You do some reading. Ever heard of inductive kick (Counter Electro-Motive Force or CEMF)? Know how the coil in a car works? Know why you need to put a reverse diode on a relay coil or the inductive filter on a power supply (especially if there's sensitive devices connected to the same source as the relay or inductor)? Know why a large motor can fry a power source that's not meant for motors (or any device connected to the same source)? Know what a Magnetic Amplifier (Mag-Amp for short) is and how it works?
By your response, you probably don't.
Many motors have magnets (especially DC, but not often AC).
PGA -- Paul G. Allen Owner, Sr. Engineer, Security Specialist Random Logic/Dream Park www.randomlogic.com
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