Learn how Automatic vs Manual control is implemented in a variable frequency drive and some things you need to be careful of.
Check out this playlist to see all of the videos in this series: https://www.youtube.com/playlist?list=PLPdypWXY_ROpXvgmlUuKDKViOFFW8YnoV
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The WEG Variable Frequency Drives give you several options on how to control the manual and automatic modes. Parameter 929 can be set so the controller is always in manual mode, always in automatic mode or is controlled via digital input 2 like we have been doing in this video series. It’s important to remember that when you switch modes, you need to be careful that you don’t mess up your system. For example, if PID has the drive running at one speed, and you switch to manual but forget to put an appropriate value in for the manual setpoint, there can be a very abrupt change in motor speed. And in some systems that could be a safety hazard, or it could damage the machine or it could cause issues with your process. And the same thing applies when switching from manual to auto. If manual has the system running at one speed but the PID setpoint is set to something very different, then when you switch to auto mode, PID may attempt to force the motor to full speed to get the process to the new setpoint. Again, that could be dangerous. There are two ways to avoid that: be REALLY careful when switching modes, or, use bumpless mode which assures a smooth transition when changing modes. This video tells you how to use bumpless mode. In this video series this wasn’t a big deal because we were just moving water around. Just make sure that if it is a big deal in your system that you take the appropriate precautions. Click here to learn more about the WEG Variable Frequency Drives. Click here to learn about Automation Directs free award winning support options and click here to subscribe to our YouTube Channel so you will be notified when we publish new videos.