Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous Motor

[Futuret <futuret@xxxxxxx>]

 I did still another test.  In this test I removed the 9 ohm, 1 watt resistor,
and replaced it with a 12 ohm, 2 watt resistor.  This resistor still got hot,
but it might be acceptable.  The motor still works about the same as in
the test below, a little better actually.  With the motor shaft held so it
can't rotate, and with 28V applied to the motor, the resistor showed
4V across it, which works out to 1.3 watts.  However the resistor 
probably gets about twice as hot when the motor is spinning because
less current flows through the armature, and more through the resistor.
I have to look around for some other resistors to try as described below.

Cheers,
John

 


 

 

-----Original Message-----
From: Futuret <futuret@xxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Tue, Jan 4, 2011 9:06 pm
Subject: Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous Motor


 I did another experiment.  I removed the diode and installed a 9 ohm, 1 watt
resistor in its place.  The resistor connects the 2 opposed areas of 3 shorted
segments.  I didn't try using 4 shorted segments on each side of the 
commutator.

The motor runs quite well this way.  It self starts, and
runs synchonously between 25V and 34V.  If the voltage is raised too high
causing the motor to lose sync-lock, then to obtain sync-lock again, the
voltage has to be decreased to 25V.  

If the motor voltage is switched on (instead of being gradually raised using
the variac knob), then the motor will sync-lock between 25V and 29V.
The current draw varies from 3.5A to 4.0A depending on the input voltage.

There is no arcing at the brushes.  Apparently the use of a diode causes the 
brush arcing.  

The only problem with this resistor method is that the resistor gets too
hot.  I can try connecting two 19 ohm, 2 watt resistors in parallel (one
on each side of the commutator).  I can also try using more resistance.
Maybe the motor can still self-start using about 16 ohms or more. 

Cheers,
John

 



 
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