----- Original Message ----- From: "Mike Hoblinski" [email protected] To: [email protected] 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