[TowerTalk] US Tower Dayton AC Motor issue

Scott McClements kc2pih at gmail.com
Tue Sep 16 19:38:45 EDT 2008

Towertalkians / Gerald,

I replaced the starting capacitor today and that didn't fix the issue.
  I guess its down to pulling this motor apart now.  Is the start
winding circuit exposed on the fan side of the motor?  I took off the
fan cover and I the fan is held by some type of nut/bolt and a snap
ring. On the end of the fan side is an aluminum piece (cap)  held on
by three bolts.  Do I remove the fan and these 3 bolts to expose the
start winding pieces?

Scott, WU2X

On Sat, Sep 13, 2008 at 7:04 PM,  <TexasRF at aol.com> wrote:
> Scott, you have described a classic case of an open start winding circuit.
> The most common cause in this part of the country is mud wasps building a
> nest around the start circuit throwout switch, causing the contacts to not
> make connection. The second most common cause is a defective start capacitor
> but this usually noticeable because of swollen areas on the end of the
> capacitor.
> The motors I have worked on have four long screws that clamp the end bells
> to the motor body. Removing these screws allows one to trmove the end bells
> and gain access to the throwout switch to examine and clean.
> Make note of all the wire colors and locations so you can return to the same
> electrical arrangement after fixing the problem.
> Hope this helps.
> 73,
> Gerald Williamson K5GW
> General Manager, Texas Towers
> In a message dated 9/13/2008 2:01:14 P.M. Central Daylight Time,
> kc2pih at gmail.com writes:
> Hi,
> I am in the middle of getting a used US Tower ready to put up. It has
> the MDLP1000 unit with the Dayton 1HP motor. Without the belt on the
> output shaft of the motor (free), I am unable to get it motor going
> full speed. It will just hum, spin slowly (like 1RPM) and blow the
> break within 3 seconds. I am able to spin the motor up to speed by
> hand and then hit the switch and it will spin up to full speed. The
> output shaft on motor spins freely and easily.
> I have a 50 foot run of #10 back to the service entrance on a 20 amp
> breaker.  Nothing else is on that breaker.  Without the motor I see
> 120V coming into the control box at the tower. When I hit the switch,
> the voltage drops to 107.5 Volts and the amperage draw is 52 amps. It
> will actually hum and slowly spin for about 3 seconds until the
> breaker blows. I am using a fluke clamp on amp meter. Not sure how it
> can pull 50 amps for 3 seconds through that 20 amp breaker, but that
> is another story.  If I check things on the main breaker, I see the
> voltage drop from 120 volts to 110 volts and 55 amps when I start the
> motor.
> If I spin up the motor by hand and the motor spins up to normal speed,
> it draws 9 amps (still with the belt off - no load on it).
> So I have read about voltage drop problems people have, but geesh, I
> am running #10 right to the breaker and its 50 feet long.  Do I need
> heavier cable or is it something else? Like maybe the starter
> capacitor in the motor?  Its a 1HP Dayton 6K622N model ("Farm Duty
> Capacitor Start"). I could probably run 220 VAC / 30 Amps to it as
> well, if this would help (and is possible).
> Thanks,
> Scott, WU2X
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