# What is Vfd: Definition and 30 Discussions

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1. ### VFD harmonics effects on generator set

I would like to use VFDs for motor sizes ranging from 0.4kw to 15kw. My idea here is to reduce the generator foot print to the lowest possible value. My thinking is that, theoretically, I could use a 25kva generator set to drive a 20hp motor (80% operating capacity) and since the VFD eliminates...
2. ### Convert 1 phase to 3 phase by using an old washing machine

We were in the process of going off grid when a tree fell over our power line. Hence we got off grid before we were ready as we didn't want to repair the power line. Now everything in the house runs on solar power, except for the well pump. The problem with the well pump is that it is a 3 phase...
3. ### Ferrite Cores on the output cable of a VFD

Some Variable Frequency Drive manufacturers (such as Allen Bradley) supply a toroidal Ferrite core to wrap the outgoing cables around to reduce EMF. My question is, if a company doesn't supply a ferrite core, how do I work out if one is needed, and how do I correctly size it? I understand that...
4. ### How can I apply a variable phase shift to an AC signal generated by a VFD?

Hey fellas, I’m trying to apply a variable phase shift (0 to 180 degrees) on an AC signal generated from a Variable Frequency Drive (VFD). The frequency is variable and ranged between 10 and 50 Hz. the voltage amplitude is also variable between 10-50Volts (this shouldn’t be a problem I suppose)...
5. ### How can I clone a USB drive to a VFD file for use in Windows?

I have a USB drive that I want to clone to a disk file to be mounted under Windows (so that I can send the file to people instead of sending them the pendrive itself). Doing so under linux is trivial with dd/mount, technically I see no reason why it couldn't be done under Windows as well, but I...
6. ### Connect grid tied solar inverter to DC+ Bus of VFD?

What solutions are there to feeding a high DC voltage rated (eg 1000VDC) certified grid tied solar inverter such as a Yaskawa Solectria PVI23-480; from an alternate DC+ bus supply. For instance the 670 VDC input from a solar string; might be replaced by a a 6 pulse rectifier; (possibly from a...
7. ### Variable-frequency drive (VFD) output without load (motor)

I have acquired an old 1.5kW/2HP VFD [1] with aim to power a drill (which I don't have yet) with a three-phase motor from the single-phase outlet in my garage. It was supposed to be in working order, but alas it was not as the LCD display, for one, is only displaying gibberish (yes, I have...
8. ### Troubleshooting a 2 Pole motor running at low speeds on a VFD

I run a small food manufacturing operation. We process nuts and seeds. We have several grinders/food processors that run at variable speeds. The speed of the motor is varied using an Emmerson VFD. The turning speed of the grinder is very low ( 50-100 RPM) arrived at using a sprocket and chain...
9. ### Why does VFD cable data sheet show Inductance, Capacitance?

Can someone point me to an understanding of why VFD rated cable include Inductance and Capacitance? For example, Belden cable 29504 shows impedance, inductance, capacitance between conductors, capacitance between conductor and sheild, and DC resistance. Is there a VFD motor calculation that is...
10. ### Fan Current to Speed (Percentage)

Hi All, I have a VFD running supply fans and I currently have two values I can see. One is the VFD actual speed percentage from the VFD. The other is a calculated Fan Speed based off of VFD current. (I control off the calculation). The calculation is (Current^.33)*25.54=%. Does anyone know this...
11. ### Can I acquire the shaft position of my motor using my VFD

The project I am working on is to design the control system for a shock dynamometer. I am using Labview and communicating to the VFD using Modbus. The shock dyno will look a little something like this; So one of the main objectives in my project is to produce a plot as seen below; The...
12. ### What materials do I need to wire a VFD?

Hi everyone, I am part of a senior design group that is building a dynonameter to test shocks. We are ordering parts tomorrow morning and so I want to make sure that I am not missing anything. I do not have any experience with VFD's or three phase motors but I am doing my best to research and...
13. ### Do I need a feedback card to acquire motor RPM from a VFD?

The VFD I plan on using; DURApulse GS3 series AC drive: https://www.automationdirect.com/static/specs/gs3drives.pdf Model: GS3-22P0 The feedback card accessory for the VFD: https://www.automationdirect.com/static/specs/gs3fb.pdf Hi everyone, I would like to know if I need this feedback card to...
14. ### Is this Variable frequency drive compatible with this motor?

My senior design adviser told me that the VFD must be the same brand as the motor that is being used, I'm not sure I believe this. I plan on using a GS1 series AC drive, here is a link; https://www.automationdirect.com/adc/Overview/Catalog/Drives/GS1_(120_-z-_230_VAC_V-z-Hz_Control) Here is a...
15. ### Is it Safe to Operate a VFD Motor Above Nominal Speed?

As many of you know, I'm an HVAC (mechanical) engineer. I do a lot of fan, motor and variable frequency drive specification. As you go from fan to motor to drive, the device goes from purely mechanical, to purely electrical, and my level of knowledge/understanding drops off... Many building...
16. ### Gate drivers for IGBT inverter: How to isolate V supplies?

This video describes my issue pretty well (I have it set to start when he talks about my specific situation): ETA: looks like the board doesn't allow the video to start at the specific time, the important stuff begins around 5:30 Our applications are a bit different as his design is for...
17. ### Servo vs ? for lift/winch/hoist

Hello. As many others here, I am starting a project that involves some engineering and will at some point, if I go ahead with it, require an engineer to design and certify. But for now I'd like to understand the principals involved and dust off some of my 1st year physics and see how much of it...
18. ### What are the Functions of VFD Control Circuits?

Hi, I,m Novice on VFDs and I was called to reconnect control circuits and program one of them for a duplex control panel(water booster system). I figured out the I/O terminals on the new drive but don't know it functions. Where I can get those function from since the only source is the old...
19. ### High quality adaptation of VFD: 1 to 3 phase; 15kw.

Hi All, I have access to a 15kW VFD for little money. I only have single phase 240 vac at home, and need to drive a 10kW motor, 3 phase, 415v. I have been reading that 3 phase input VFDs can be run on single phase, but they must be derated by 50%. This would mean a 20 kW VFD. Also, it is a...
20. ### VFD use to maintain constant flux

When using a VFD, am I right in thinking that for an induction motor, torque available at all speeds is constant as the voltage is reduced with frequency to maintain constant flux? Also, am I right in thinking that the mechanical output power of the motor will be less when speed is reduced, as...
21. ### Amperage draw versus Air flow VFD Fan

I have a VFD fan that pushes air through a filter. Over time, downstream resistance gets higher due to the filter. Fan speed remains constant. We have looked at amperage draw and it has remained stable even with this added resistance. Does that mean that air flow remains constant? Kind of...
22. ### Automatic rail system vfd type vs torque

Working on a problem with an automatic rail system used to transport cows. This rail system carries a substantail amount of weight so starting torque is the issue coupled with washdown ( rust) issues. The system runs well normally even fully loaded. However has nuisance over amps on startup...
23. ### Electrical service for a VFD motor

I get very confused with AC electrical service, I'm a mechanical engineer so these things just confuse me. DC makes perfect sense to me. Anyway, I need to supply a single phase motor with 230V (the specs say 230V +/- 10%), so that would make my tolerance 207V to 253V. The motor is for a...
24. ### Torque or horsepower needed for 3 phase gearmotor, brake, VFD

I’ve built a light weight frame for a hoist which only needs to lift around 500 lbs. The cable spool needs to hold 250’ of 3/16 cable that can lift a submersible pump from that depth. The hoist will also be used to develop the well and without going into great detail about this, I’ll just say...
25. ### Understanding VFD & 3 Phase AC Motors: Torque, Speed, and Voltage Explained

Hi, I am trying to understand the concept of the VFD & the AC motors running on three phase . I have briefed about the concept involved with the VFD what i understood;--- Torque --- directly proportionalt to applied V^2 speed --- directly proportionalt to frequency One way to...
26. ### VFD - 36 Pulse Unit Advantages

Hi, I would like to ask if anyone with VFD and PWM - Invertor knowledge could give me a run down on the advantages of a 36 Pulse VFD Unit in comparison to a 12 Pulse? Is the cancellation of harmonics a factor in Pulse selection? Thankyou C
27. ### Difference between VVD and VFD

Hi all, :smile: Can someone please tell me the basic difference between a Variable Voltage Drive (VVD) and a Variable Frequency Drive (VFD) in terms of industrial applications. Why can't VFD be used for all speed control applications or the likes in general?... i.e., why a requirement of a...
28. ### How does motor slipage affect fan performance with a VFD?

Im a HVAC contractor/designer. I am looking to install a fan unit with a VFD. This is 3 phase, 60HZ, 460 volts, 40HP AC motor. Im trying to create a "system curve" like a fan curve that would show the cfms at various frequency settings being changed by the VFD. I can reiterate or...
29. ### Can a 2-Pole Motor Handle 600 Tons? VFD and Motor Question - Expert Opinions

Hi all, I have a 75kW high load Ac drive and a 75kW 4 pole 3 phase motor that is supposed to be used for a winch pulling horizontaly. The customer connected the Vfd to a 75kW 2 pole 3 phase motor. Now the question is will this 2 pole motor be capable to develop enough torque to pull a...
30. ### VFD problems motor not running?

Hi all, I am new on the forum. I have a customer who is having some problems with running their motor with the VFD. I realized they had tampered with the setup parameters and luckily we corrected all the parameters. However, they have gained control on the motor, but the motor is...