[amsat-bb] Re: G5500 Rotor motor Question (amended)

i8cvs domenico.i8cvs at tin.it
Sun Apr 28 13:07:00 PDT 2013

----- Original Message -----
From: "Mike Hoblinski" <hobergenix at sbcglobal.net>
To: <amsat-bb at amsat.org>
Sent: Sunday, April 28, 2013 7:55 AM
Subject: [amsat-bb] G5500 Rotor motor Question

> Anybody know what the rpm of the AC motors are. I know from the Yaesu
> specs that after all of the gear reduction they list EL as 67 seconds for
> EL and 58 Seconds for AZ.
> I would like to experiment with an AZ and EL system but like to see what
> RPM the motor starts out with and how much torque to get the final
> results. They show Elevation at 101 FT-LBS and AZ at 44 FT-lbs.
> I have looked around to see if somewhere the specs are available for the
> motor but have had no luck. I have seen quite a few pictures of rebuilds
> of that rotor with part number and have a manual that shows parts.
> Mike Hoblinski
Hi Mike, N6IMF

Apologise..........My previous message was wrong !

This one is correct.  

The EL and the AZ motors of a G5500 rotator are squarrel cage AC
asynchronous motors.
The stator is wound with 4 crossed coils.
A couple of 2 opposite coils is the pole North-South called P
P = 1 because every 2 coils represents one pole P and it is used to
run the motor.
The other couple of 2 opposite coils is used with a capacitor 
in series only to generate a current 90 degrees out of phase to
start the motor.

The RPM (revolutions per minute) of a asynchronous motor is given by the
following formula:

                 f x 60
RPM = -------------  - S  


f    = value of the frequency in Hz of the supply AC power 
60 = 60 seconds into a minute 
P   =  number of pole expansions of the motor 
S   =  speed of gliding  ( 7 % for small motors )

If you supply the motor with 24 volt 60 Hz as in USA than

                60 x 60
RPM = -------------- = 3600 - 7% = 3348  

When you run this motor in Europe with 50 Hz AC than the
speed is reduced to 2790 RPM  

73" de

i8CVS Domenico

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