Speed Matching.


Thread Starter

Stressed Tech

I am currently trying to find a way to match the speeds of two machines with each other. One machine has a two speed AC motor with a variable
speed pulley. The other machine is ran with an AC frequency drive using an external pot. Am I correct to assume that the easiest way to
match the speeds is to use an encoder on the two speed AC machine going to a PLC w/high speed counter and then drive the 4-20 ma input on
the frequency drive? Any help would be highly appriciated.

Davis Gentry

As long as the machines are not high speed and the accuracy of the matching is not too critical this will work. The other posting about the black box will work about the same. If matching is critical (for example a pair of machines with a web of some kind running between them - e.g. a printing press or high speed can making machine) you will need a controller which can control both motors and keep track of any deviations.

Davis Gentry
Delta Tau Data Systems
If the motors you mentioned above are operating for in-line torque control (downstream motor speed varing to compensate the overall line speed, not direct following the upstream motor speed.) Your attemping to follow the motor speed
may not correct. If the downsteam motor (AC frequency controlled) was designed to get feedback from a pot. (dancer feedback) it was designed to maintain its tension not the speed with upstream one. Some frequency controller allow to take dual input for control the performance. If possible, take one input from
upstream reference voltage or frequency as base reference for the downstream, then take the dancer feedback to compensate the difference to maintain the tension. You can adjust the ramp-up/down or PID parameters to correct the
timing problem. Hope this help...