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Re: Rotor & sync motor


From: 	gweaver[SMTP:gweaver-at-earthlink-dot-net]
Sent: 	Monday, September 15, 1997 11:50 PM
To: 	Tesla-at-pupman-dot-com
Subject: 	Rotor & sync motor

I have been thinking about building a rotor for my 10" TC.  After reading
all the post for the last 4 months about rotors I have come up with this idea.

One post mentions that most people build a rotor with 2 series gaps.  But a
rotor with 4 series gaps would be much better.

Another post mentions 2 gaps are all that are needed and 4 are more than
enough for a rotor.  More than 4 are wasted.

Several posts mention that the rotor should have no more than 400 bps and
less is better.  Nothing is gained by having more bps.

Several posts mention dwell time as being very important.  Fewer bps gives
longer dwell time. And small electrods are better than wide ones.

I think I will build a rotor that will fire one time for every 60 Hz AC
peak.  I don't see any reason to make it fire more than once for each peak.

2 rotating electrodes on a 9" disk and 2 stationary electrodes using an 1800
RPM sync motor will give 120 Hz.  It will fire on each + and - AC peak.

2 additional stationary electrodes opposite the other 2 stationary
electrodes will give me 4 gaps with them wired in series.

How does this look so far?  Does anyone have any suggestions.


I called my friend at the motor shop about a sync motor.  He said they don't
make sync motors any more with out special order and they are very
expensive.  True sync motors have a wound armature with slip rings and
brushes.  No used sync motors are available.

Some information on the internet says 4 flats can be milled in the armature
to make a 1750 RPM run sync.  Most AC motors are 1725 RPM.  My question is,
will this work on a 1725 RPM motor? My next question is, will the flats make
a 1725 RPM motor run at 1800 RPM?

My friend at the motor shop said he thought the flats would make a 1725 RPM
motor sync at exactly 1725 RPM's.  And a 1750 RPM motor would sync at 1750
RPM. But it seems to me like the flats will have to sync with the 60 Hz AC
and run exactly 1800 RPM's.  Has anyone tried this? Does this really work?

I have a 1/4 HP 1725 RPM 120 VAC motor I can use to make a sync motor.  If
this really works I will mill flats in the armature and use the motor on a
rotor.

Gary Weaver