Lesson 1 - Understanding the VFD Variable Frequency Drive

hi guys my name is Rajvir and welcome to NFI online tutorials on VFD variable frequency drive so in this video we are going to see a basic basic overview of what is a VFD? What are the different terminals how to connect your motor to a VFD so these are the couple slides which I'm going to use to explain this is the video demonstration that's the drive that's how a VFD looks like okay that's the three-phase induction motor which is connected to the drive using this wire over there this is the keypad display and that's the input or supply which I'm giving to the drive which is 220V single-phase okay that's the frequency display as of now this is how our drive setup look like now the drive which I'm using here is 1.5 kilowatt of Delta, oK! so this is M series 2 HP drive alright which says input of 230 volts 1/3 phase now this means the input of this Drive the input which is coming here that should be 230 volts it can be single phase or it can be three-phase you can see here l1 l2 l3 because in some countries we have 230 volts as three-phase in some countries we have 440 volts and three-phase so in my in my country we have single phase as 230V and 3 phase as 440 volts so I have applied a single phase of 230 volts to this drive. so this Drive will give the output of 230 volt 3-phase that's the drive configurations so that 3 phase output is going from this wire to this motor. Alright! so if you want to see in the diagram how does it look like it's like that this is a diagram representation of a drive these are the input terminals so I have connected line neutral and these are the two contacts of a relay you can also take a contactor if you have a three-phase supply so that's the coil which I am using this is the push-button you know this is same thing as the coil that's how I have latched this coil and the the contacts of this coil so what happens when you press this 'A' this will be latched and this will start giving supply line and neutral to your drive and this will unlatch so these two push buttons can be used as a latching and unlatching to start and stop the drive like that okay that's how this is a diagrammatic explanation to that okay so in this drive I'm not using this Start/Stop switch besides I'm using this MCB to start and stop my drive this is a MCB ok? this is giving a line neutral signals to my drive here okay let's go back to this angle alright so let's see the first slide which says VFD status screens we have different status on the drive now VFD is used to control the frequency okay if you see here it says motor RPMs equivalent to 120 F/P this if this is a factor frequency which says it's directly proportional to the motor rpm so what does it mean if your frequency is let's say 50 Hertz okay generally motor runs at 50 Hertz frequency in few countries it's 60 Hertz let's talk about 50 Hertz at 50 Hertz the maximum RPMs 3000 rpm okay so at 25Hz, rpm will be 1500 because these are proportional these are directly proportional so let's see the status screen the first screen talks about motor is OFF because you can see this red LED here the same LED you'll find here it says motor is off okay and this is the frequency this is the command frequency which we command from the drive okay so that's the command frequency then you have output frequency denoted by 'H' so if I press this mode here you will find 'H' right now 'H' is 0 because motor is off so output frequency is 0 then you have parameters by 'P' direction as forward and ampere as 'A' so i press mode again this is the Ampere right now which is 0 ampere motor will stop this is the direction this is the internal counter value which you can change as well I'll show you in the later slides. This is the command frequency so these two switches green and red these are the run and stop switch. So when I press 'run' your motor will start running you can see here and that's the command frequency in this case this is the output frequency so if I stop the motor will find frequencies decreasing going back to zero when I run the motor frequency will increase up to the command frequency: 12.2 Hz which is over here 12.2 Hz now in that case your current has been increased to 0.1 Ampere so here you find the status of your Drive of your motor what's all happening there okay so let's move ahead now we have different terminals these are the control terminals which you'll find over here these terminals you have this highlighted view of these terminals here so it says relay feedback RA, RB and RC these are the three terminals by which we can have a feedback from the drive now a feedback can be in you know in various cases for example when your drive is running this can give you a feedback when you drive a stop, this can give you a feedback when your drive has attained maximum frequency or some desired frequency or if there if there is any fault this can give us the feedback. So these are the feedback terminals one more pair is their MCM in MO1 these are the feedback as well so you have two feedback terminals RA, RB, RC, MCM and MO1, all right MO1 and these are the control terminals from M0 to ground now these term control terminals are used to control the frequency in steps to control the operation start/stop directions it's different step speeds jog operation you can control from here one way is to controls from here from start and stop this is the control mode from the keypad but if you want to have external start and stop from let's say from this panel which is here you can do that by selecting your control panel on these terminals which is M0 to M5 okay then you have one AFM this is analog frequency meter it's a feedback which you'll get based on 0 to 10 volt if the frequency is 0 Hertz we can get zero volts feedback this frequency is 50 Hertz you get 10 volt feedback so that's the feedback proportional to the frequency this can be proportional to current as well. By changing the parameter so that's the feedback which you can read in your PLC or in your HMI and you can display that on your screen for the monitoring purpose then you have a ACI and AVI which is analog current input and analog voltage input these are the two sources by which you can change the frequency of your drive by this range by current of 4-20mA you can change the frequency from 0 to 50 Hz you can change that !hey this is a source of frequency terminal and if you are having a voltage source of 0 to 10 volts still you can change the frequency by applying the voltage at AVI these are the two frequency control terminals this is plus 10 volt internal power supply ground is a common of the drive. So these are the these MCM and MO1 is the output feedback terminal as I have shown you. So I have also made this terminals over here from M0 to M5 so what I have done is I have connected these terminals to the PLC if you see here we can analyze this diagram this is the output card of PLC okay so M0 is connected to Out0 and M1 to Out1 similarly up to M5 to Out5 and this ground is going to 'Common' I will tell you what is the fundamental behind that fundamental is when you connect ground to your M0, M0 get active! So we can perform functions with M0, M1, M2, M3, M4 up to M5 if we're going to ground to this any of the terminal so what i'm doing here is if I turn on my Y0 from the PLC this ground will travel from common to Out0 you will understand what I'm talking about if you have seen my earlier videos of PLC what happens when you turn on the outputs ground gets short into your output terminal ok so this M0 will get the ground and Y0 is on M1 will get the ground when Y1 is ON and so on ok! So this is I have already made the connections and this ACI and AVI and this 10 volts and ground these can be used to change the frequency so right now my terminals are connected like this is my DA card channel 2 channel 2 is going to my ACI we can use AVI terminal if we are using here if you use here V+ so analog voltage this channel 2 is the channel 2 of DA card which is Digital to Analog Card. So channel 2 is connected to AVI so I will be giving voltage from this channel to control the frequency of my drive and this is the if you see here AFM and ground this is connected to channel two of A/D Card which is analog to digital this is to monitor the feedback of your drive in your PLC so this is already linked with the PLC in the panel and if you wanna see a little look find a PLC and an Analog Cards which are connected to the drive signal from there is coming to this one by this terminal box this is how I have extended the supply of the drive this is going via the PLC it is how the drive is connected all right so we have already made this terminals. Next is we have motor output terminals coming from here this is over there you can see that three-phase output coming going to the motor then motor brake terminals if you are having as you're applying a break you need to use a brake resistance because we need to drop the back EMF voltage somewhere so we apply resistance to the brake terminals B1 and B2 because you need to drop that voltage so that is used for that case then you have inputs these are the input terminals - over there okay here we have three phase or single phase 220v AC this is the this is how we can give the voltage to your drive alright so right now drive is ON if you want to see if I run this drive this will start the motor and this will stop the motor so that was about basic introduction about one of the different terminals a lot of different components of your drive and how you can use that so in another few videos we'll see how we can control the drive by choosing the parameters alright thank you

Channel: Rajvir Singh

Views: 279,908

Rating: 4.7368059 out of 5

Keywords: Variable-frequency Drive, VFD, VFD Tutorials, VFD Lesson, What is VFD, How VFD Works, nfiautomation, Understanding VFD, How VFD works

Id: IgQ52FY20uM

Length: 10min 49sec (649 seconds)

Published: Sun Mar 23 2014