Learn how to use an analog input to control the speed of a motor using a potentiometer on the WEG CFW100 and CFW300 Variable Frequency Drives.
Let’s add this potentiometer to analog input 1 so we can control the speed of the drive by rotating a knob instead of using the up and down arrows on the keypad. I’m using a CFW100 for this video. The CFW100 drives don’t have an analog input on the base drive so we have to add an option module with an analog input. I’m using this one, but you can use any module you want that has an analog input. The CFW300 has an analog input on the base drive, but since it is analog input 1, everything we do in this video – minus adding an option module - will apply directly to the CFW300 family of drives too. I wired this potentiometer to analog input 1, like this. I’ll apply power to the drive. Let’s go to parameter 204 and set it to a 5 to reset the drive’s parameters to factory default, just so we are all starting in the same place. You wouldn’t do that if you have an existing the configuration you are trying to modify. First, we need to go to parameter 231 to tell the drive we are using analog input 1 as a speed reference. According to the manual, we need a zero for that, and as it turns out, that is the default, so we are good to go there. Next, we need to go to parameter 233 to tell the drive we are using the analog input as a 0 to 10-volt signal. The manual tells me that needs to be a zero and again that is the default for this drive, so we are good to go there. To verify we did that correctly we can go to parameter 18 which shows us the value the drive sees on analog input 1. Rotate the potentiometer and sure enough full counterclockwise gives me a zero reading and full clockwise gives me 100%. Perfect. I’m going to put that back at zero so we don’t get any surprises when we connect that to the motor. If you used analog input 2, then you use parameter 19 to view the potentiometer value. Great, we know we wired things correctly and that the drive sees the potentiometer on analog input 1. And we really haven’t done anything yet because these were all the default values for this configuration. But don’t assume that – always check those parameters just to be sure they are what you expect. So the only thing left to do is tell the drive to use the potentiometer on analog input 1 and not the keypad to control the frequency of the drive which will control the speed of the motor. To do that we go to parameter 221 because we are using this drive in local mode. You would use parameter 222 if you are setting this up in remote mode. The programming manual says we need to enter a 3 to tell the drive to use the potentiometer BUT – that’s the potentiometer on the potentiometer option module which has its own dedicated configuration. We are using the potentiometer on analog input 1 so we need to enter a 1 for parameter 221 to tell the drive to get its speed reference from analog input1. So, all we did was wire the potentiometer to the analog voltage input and change one parameter. I’m gonna scroll to parameter 2 so we can see the drive's frequency and double-check that the potentiometer is all the way counter clockwise which we know is a zero. I’ll hit run and the drive goes to its min speed which we can change in parameter 133. If I rotate the potentiometer, sure enough the drive frequency changes. If I rotate it all the way clockwise, the drive goes to the max speed which we can change in parameter 134. We can change parameters 100 and 101 to change the acceleration and deceleration to make the Potentiometer feel more responsive if we want to. We’re not gonna do that here. Well, that’s all there is to controlling the drive with a potentiometer. If you want to use the analog input for some other process, like PID, then the WEG drives also have parameters that allow you to massage the analog input to optimize it for your process. This little drive is packed full of high end features like this which is what makes it such an amazing value. Again, we have lots of videos showing you how to get the most out of your WEG variable frequency drives. So, click here to learn more about the WEG family of variable frequency drives. Click here to learn about AutomationDirect’s free support options and click here to subscribe to our YouTube channel so you will be notified when we publish new videos.