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Dear Sir,
Thank you for your interest. The PLC you called out has either 20 mA DC analog input or 10 volt DC analog input. I am assuming that you are going to take the feedback from a transducer and control automatically the raising and lowering of the brushes.
This is obviously a classic closed loop control system, with a reference point of 9 to 11 amps. Once you write your control law (overcurrent raise the brushes, undercurrent lower the brushes) the next step and probably the most difficult will be the time delay or response. Too little time delay and it is possible that the system could be unstable. Too much and it will not respond to natural variances in the process.
The standard style current transducers we have contain circuitry that gives them about a 250 mS response time. A step change in input will result in a change in the output that reaches 90% of designed value within 250 mS. You will need to review this to make sure that the delay in reading time plus the delay from your control programming will react fast enough to properly control the result. I would think it should be.
The CR4400 series of transducers is the one I would recommend. I would get the 15 or 20 amp range so the control band is about ½ to ¾ full scale.
If the response time is too slow, I have a couple of other ideas that could improve the 250 mS response time
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