I checked....This is a dual winding integrated 6000 rpm 100hp VAC motor on our Okuma MCV bridge mill. (Big Big Iron!)The Hall effect sensor is mounted on top of the motor with the encoder rotor mounted directly to the motor shaft. I have replaced this encoder before. The motor shaft bearing failed and let the encoder rotor smack the sensor. The Z pulse is used for orientation of the spindle for automatic tool changer functions on this machine. The signal from this encoder on the A and B signals are sinusoidal. The drive manual says they are used as a speed reference. Okuma says it is a Hall Effect Sensor. I confirmed with their service department. Maybe it is not a true Hall Effect? At least that is what they tell me....The sensor is adjusted by monitoring the signals before they are processed in the amplifier to adjust amplitude. The closer the sensor is to the rotor the higher the amplitude. Is this different in a brushless dc motor? Again, this is probably the extreme limit of my experience with them. Most our motors (even brushless dc) use high resolution optical encoders. Most of our systems are AC or permanent magnet DC. Out of 50 machines this the only one we have now that has a "Hall Effect" (or so they say).
Dave ----- Original Message ----- From: "Jon Elson" <[EMAIL PROTECTED]> To: "Enhanced Machine Controller (EMC)" <[email protected]> Sent: Tuesday, October 23, 2007 12:27 AM Subject: Re: [Emc-users] Brushless Amps > Dave Keeton wrote: >>>The motor has only Hall sensors. Do the Hall sensors have an analog >>>output in order to be able to position the rotor at a desired angle from >>>the sensors? >> >> >> I think that Hall Effect sensors are sinusoidal output. At least >> with my experience with them. The ones that I have worked with have an a, >> not a, b, not b and z, not z. They are converted to TTL square wave in >> the >> drive itself. > I think you will find they are digital coming out of the motor. > They work more like an Inductosyn linear scale. Signal >> amplitude is critical, to much and the drive will start clipping and >> giving >> you false feed back or throwing alarms. I think plain old encoders are a >> better bet for a bridgeport. Hall effect sensors are to sensitive and to >> expensive to replace if you need to. > Real Hall sensors are buried in the motor, and would require > extreme surgical measures to even get to them. Many brushless > motors with "industry standard" hall outputs use a Renco encoder > which gives ABZ plus the "Hall" signals. > > Yes, optical encoders are great, but you still need commutation > signals from the motor to properly drive a brushless drive. > > Jon > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. > Still grepping through log files to find problems? Stop. > Now Search log events and configuration files using AJAX and a browser. > Download your FREE copy of Splunk now >> http://get.splunk.com/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
