What is a VFD? (Variable Frequency Drive)

welcome to another informative video brought to you by real pars today you will learn about VFDs specifically what they are and when do we use them with automation and PLC's [Music] before we get started on today's video if you love our videos be sure to click the like button below then make sure to click Subscribe and the little bell to receive notifications of new real Parrs videos this way you never miss another one so what exactly is a VFD well it stands for variable frequency drive they are used for running an AC motor at variable speeds or let them ramp up their speed to give them a smooth startup some people simply call them drives they work by adjusting the frequency of the motor to adjust the RPMs to do this a VFD will actually convert the voltage twice first it converts our three-phase AC to DC this is accomplished with diodes then it cleans the DC with a capacitor next it will convert the DC to AC this is accomplished with transistors acting as switches utilizing these switches is what allows the VFD to adjust the frequency that the VFD supplies to the motor this in turn controls the speed of the motor now I know this is a lot of information to take in let me compare the internal workings of the VFD with a simple plumbing system first let's look at the diodes that convert the AC to DC this operates like a check valve in a water system a check valve like a diode with electricity only allows water to flow in one direction the capacitor acts as a water filter to keep everything clean and usable the transistors act like valves they turn the flow on and off when needed this allows the VFD to adjust the frequency of the motor now that we have an understanding of how a VFD works let's see what they're used for one very common use in industry is to control the speed of a water pump in a water treatment facility a water treatment plant typically has a constant flow of water coming into the plant however if the water demand exiting the plant is lower than the supply entering the plant then the operator will need to slow down the supply this is achieved by using a VFD on the AC motor the operator can monitor water flow and manually adjust the VFD accordingly another great thing about VFDs is the fact that they can be controlled with a PLC using basic communication protocols that have been covered in previous videos such as rs-232 and rs-485 PLC's can monitor and control motor speeds using the VFD this helps make a process like water treatment that much easier and more efficient this setup can be used in any situation that would benefit from automation let's look back at what we now know VFD stands for variable frequency drive they are used for controlling the speed of an AC motor they are also used for ramping up a motor for a smooth startup or to prevent a heavy load from straining the motor on startup this is accomplished by adjusting the frequency delivered to the motor setup of an AC to DC converter then DC to AC converter VFDs are used throughout industry a common example is to regulate water flow entering a water treatment plant VFDs allow the operator to control the flow of the pump manually or automatically with a PLC there are many different brands and features available if you're looking at using a VFD just be sure to do your research i hope this videos helped you get a feel for VFDs they really can make any automation or industrial process operate more smoothly make sure that you head over to real parse comm to find even more training material for all of your plc programming needs [Music]

Channel: RealPars

Views: 889,879

Rating: 4.9316831 out of 5

Keywords: VFD, Variable Frequency Drive, drive, motor, PLC, water pump, water treatment facility, controlling the speed of an AC motor, smooth startup, adjusting the frequency, AC to DC, DC to AC converter

Id: g7jFGOn6xfU

Length: 5min 20sec (320 seconds)

Published: Mon Oct 29 2018

Reddit Comments

[u/VeeCidiani]

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