Motor speed control with Encoder

[ger1]

Hi, If I have an encoder monitoring the speed of a 3 ph motor controlling a varying load conveyor, how do I use this to keep the motor speed constant. I mean what is the simplest way of doing this - do I need a PLC or can it be done with an Inverter? Cheers

[BobLfoot]

Talk about an open ended question. Most modern AC Variable Frequency Drives once you get beyond the hand held / breadbox sized versions can so closed loop speed control with an encoder relatively easily. I would ask what Encoder and Electronic Device do you ahve monitoring the speed right now? Going to an AC Variable Frequency Drive may mean a change of encoder style and type.

[ger1]

I phrased the question wrongly - It is something I am going to undertake and I was just wondering if it is possible? What type of encoder would you use, how would you set your set point, etc?

[BobLfoot]

I'd suggest the 700 series VFD from Allen Bradley or one of the GE series 300 or 3000. Whatever the GE was we used a 9030 plc.