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A system I'm working on calls for measuring and registering, among many other variables, the steady-state speed of a 50 hp drive-equipped DC motor with a PLC system. Right now, the speed is monitored through an indicator that measures and scales the armature voltage accordingly. The plant's technician tells me that speed is proportional to armature voltage, and that I only need a signal conditioner to scale down the 180 VDC maximum armature voltage to a level suitable for the PLC analog modules.
I don't have experience in DC motors (and don't remember anything about them from my days at school), but assuming that it is a shunt motor and/or the voltage across the armature is being correctly measured, is it correct to assume speed as being proportional to armature voltage? If true, if I measure the voltage with a conditioner, should I use a special one that takes into account any possible peaks or ripples from the DC drive's output, or are they negligible and a simple 0-200 VDC to 0-10 VDC or 4-20 ma isolator/converter will do?
Thanks a lot for any comments.
Pat
I don't have experience in DC motors (and don't remember anything about them from my days at school), but assuming that it is a shunt motor and/or the voltage across the armature is being correctly measured, is it correct to assume speed as being proportional to armature voltage? If true, if I measure the voltage with a conditioner, should I use a special one that takes into account any possible peaks or ripples from the DC drive's output, or are they negligible and a simple 0-200 VDC to 0-10 VDC or 4-20 ma isolator/converter will do?
Thanks a lot for any comments.
Pat