GS4 VFD - Sleep Mode Intro and Overview

The GS4 Variable Frequency Drive has several sleep modes you can use to automatically turn the drive’s output frequency to the motor on and off. Sleep Mode 1 simply monitors an analog input to decide when to turn the motor off. Maybe you have a tank filling application where you want to control the motor speed from an ultrasonic distance sensor. When the tank is water level gets close to empty and crosses a level you set, sleep mode will automatically turn the motor on to start filling the tank. When the tank level rises to the level you want, Sleep mode automatically turns the motor off. You could do the same thing with pressurizing a system or heating and cooling system, etc. Pretty much any process where the drive needs to get the system to some level and then turn the motor off until it falls to another level where it turns the motor back on. Sleep mode 2 uses PID to control the drive frequency and watches the drives output frequency to make its decisions. This is handy in PID controlled applications. Without sleep mode, as the water approaches the set point, the drive will want to slow the motor down as the process variable approaches the setpoint and ultimately go to zero speed as the water level reaches the setpoint. But, most centrifugal pumps become very inefficient at medium motor speeds and cease pumping all together at lower speeds – typically at a drive frequency of around 20 to 25 Hz. Sleep mode 2 watches the drive’s output frequency and automatically turns the motor off before it gets inefficient or stops pumping. And that saves you money because you are only running the pump motor when it makes sense to do so. Sleep mode 3 is a lot like sleep mode 1 – it monitors the analog input to make its decisions. But, since it is using PID to control the motor speed, that analog input is actually the Process Variable of the PID process. Just like mode 1, it watches the analog input – or Process Variable - to decide when to turn the motor on and off. This difference is PID is automatically controlling the drive speed so you don’t have to. Mode 1 requires modifying some drive parameters to ensure everything works as expected and if the levels change you have to go back in and modify those parameters again. Sleep mode 3 does that for you automatically because it’s using PID. There is a whole set of videos showing you step by step how to do this and we even do a reverse acting PID example for mode 3 just so you can see how to do that. And check out the PID video on tank filling if you want to see how we setup PID for these videos. Click on the info banner that just appeared at the top of the screen to go directly to those videos. Click here to learn more about the GS4 Drive. Click here to learn about AutomationDirect’s free award-winning support options and click here to subscribe to our YouTube Channel so you will be notified when we publish new videos.