----- Original Message ----- From: "Mike Hoblinski" <hoberge...@sbcglobal.net> To: <amsat-bb@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 > > N6IMF > > 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 P where: 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 1 When you run this motor in Europe with 50 Hz AC than the speed is reduced to 2790 RPM 73" de i8CVS Domenico _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb