Questions tagged [vfd]

Variable frequency drive, a three-phase AC output motor controller. Questions about vacuum fluorescent displays should not receive this tag.

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Modbus RTU on ESP8266 to control VFD

Hoping to get some help on setting up a NodeMCU (esp8266) with this 1 arduino library to control a Variable Frequency Drive (VFD). I'm afraid to say that I almost need help from square one, as I'm ...
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0 answers
17 views

How much lower than the ideal torqe curve is the actual torque of a PMSM running at overspeed?

VFD-controlled PMSM's are said to produce constant maximum torque up to the rated speed. Above the rated speed the VFD performs defluxing and produces constant power. This should then mean that at 200%...
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1 vote
2 answers
45 views

Can you run two motors of different hp off the same VFD independently?

Can you use the same VFD to run two motors of different hp (20 hp and 10 hp) if all other parameters are the same? The motors will never run at the same time, it will be one or the other, and the ...
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1 vote
1 answer
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What must be considered when selecting a VFD-controlled PMSM that will be freewheeling beyond its nominal speed?

With a given two-pole motor, with all else being equal, if the pole count is increased to 6, the nominal speed will be reduced to 1/3. Can it be freewheeled to the same speed as the original 2-pole ...
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4 votes
2 answers
104 views

Help to diagnose 3-phase induction motor stuttering

I’m working on a project where I want to run a 3-phase induction motor (see picture for specifics) using a VFD (Variable Frequency Drive). The VFD I have is a cheap Chinese one (the “T13-750w-12-H”), ...
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1 answer
94 views

Magic smoke from "AC 50-500V LED Digital Voltmeter Ammeter" when connected line-to-line on output of VFD

I wired 3 "AC 50-500V 0-100A Persegi LED Digital Voltmeter Ammeter 110V 220V Tegangan Saat Ini Meter Voltammeter Mobil Volt Amp Tester Detektor" like this (but I paid a lot more for them...)...
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1 answer
45 views

Using one variable frequency drive for 2 motors (one at a time)

Is there any issue using one VFD, to run 2 motors— one at a time using a selector switch? So 3 phase in the the VDF— the frequency is modified and comes out the VDF— into a switch intended to switch ...
0 votes
1 answer
37 views

Will a 3-phase variable frequency drive have any effect on voltage differences between phases?

The national power provider here is not great. There is often a 10 - 30 V difference between phases. Will the voltage exiting a 3-phase variable frequency drive be the same as the input voltage, or ...
0 votes
1 answer
56 views

12 VDC to 380 VAC for 1 kW, 3-phase motor

What is the cheapest way to run a 1 kW, 3-phase motor for about 20 minutes on a 12 VDC battery? Will it be a 2 kW inverter to power a VFD or is there something else? And will a 100 Ah battery do, and ...
2 votes
4 answers
391 views

Variable Frequency Drives for slowing down a motor

I am changing my water pump over form a diesel engine to electric motor. Problem is the motor i have is too fast, and it will be complicated to replace it. The pump requires more power the faster it ...
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1 answer
17 views

vfd 3 or 1 phase input how is voltage adjusted

I bought a cheap VFD (variable frequency drive), it takes 3 phase input, but allows too for 1 phase input connecting the neutral and phase on the the first and third phase input. The vfd to my ...
-1 votes
2 answers
101 views

If a VFD-driven induction motor can be operated as a generator, what will be the voltage and frequency of the generated voltage?

It is known that when an induction generator is connected to the grid, the frequency and voltage of the electricity generated will be that of the grid but when the VFD is connected inbetween grid and ...
2 votes
1 answer
50 views

Can I use a 3-phase driver like FNB41560 on 1- and 2-phase motors too?

I want to reduce complexity on buying many different parts and design different circuits. So I'm thinking if I can buy just FNB41560s that are well priced and simple and are capable of driving 3-phase ...
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3 votes
2 answers
217 views

Can the output voltage of this variable frequency drive (VFD) be varied?

I am looking to buy a Cutler-Hammer "Adjustable Frequency Drive" AF91AGO BF25D. I’m a bit confused even after going through its datasheet. Can the output voltage of this VFD be varied from 0-...
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1 answer
155 views

400 V, 3-phase electrical motor on 230 V, 3-phase supply WITHOUT rewiring?

I have a what I assume is a very unusual question, and an unusual situation. I do appologize if it has been explored before, but I could not find anything about it when searching. I also appologize ...
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2 answers
49 views

VFD speed reference command: Will MODBUS/TCP have better resolution than 4.0 ~ 20.0 mA

I need help to understand the difference between tranditional 4.0~20.0 mA and digital communication (for example MODBUS/TCP) Assume: a PLC communicates with a VFD to control a variable speed pump from ...
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-1 votes
1 answer
103 views

VFD minimum speed (frequency) and speed reference signal mapping

I am new to VFD configuration. Suppose I am using VFD for a variable speed pump control. The VFD is programmed to have minimum frequency 30 Hz and maximum frequency 60 Hz. The VFD receives its speed ...
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21 views

Filter selection for a VFD output to minimize reflection that could damage the motor

Im installing a vfd for a submersible pump, i have read long cables causes problem for both the VFD and motor as voltage reflections cause large voltage spikes upto 2x the operating voltage. My cable ...
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1 answer
58 views

How to visually display 3 phase output

We have inherited a PCB and must redesign it. Unfortunately, only the PCB was provided, no schematics or documentation. I know the PCB controls a VFD (which we have been given) and whilst I know we ...
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65 views

Choosing a motor

Long time listener, first time caller etc! Also, if you think this could be better answered somewhere else please let me know. I'm building a pottery wheel at the moment and I'm in a bit of a quandary ...
-1 votes
1 answer
35 views

Difference between voltage measuring from induction motor junction box and VFD output terminal

I want to measure stator voltage of VFD fed induction motor. It's common to measure from juction box, which should be the exact stator voltage of induction motor, but I wonder if it's possible to ...
1 vote
3 answers
221 views

How can the energy produced by a generator be fed back to the motor that rotates the generator?

The drawing below shows an induction motor (IM), powered from the grid through a variable frequency drive (VFD). This IM, through a gearbox, rotates a permanent magnet synchronous machine (PMSM) ...
12 votes
4 answers
4k views

Why does the current carrying capability of a cable increase with temperature

I'm specifying cable for a VFD application and came across this table regarding NEC ampacities and corresponding cable size. What I found interesting is that the ampacity increased with temperature ...
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163 views

How is power consumed by an induction motor calculated based on speed (from a VFD) and torque induced by the rotor shaft?

I've been tasked with carrying out some design improvements on my company's production floor. There is a flat belt conveyor assembly line, whose movement forward movement is controlled by a single ...
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1 answer
118 views

Is a change-over-switch with a VFD dangerous?

We are using a variable frequency drive (VFD) with a compressor. We added a rotary cam changeover switch (600 V/50 Hz, picture is attached) in between the compressor and the motor. The purpose of ...
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2 votes
2 answers
100 views

Regenerative Drive VFD when drive is a major % of network load?

I'm in the process of designing a new facility with about 50-60 VFDs in the 5-10 HP range, another 5 VFDs in the 100-225 HP range, and then one burly beast at 1000 HP. I've been looking into various ...
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1 answer
139 views

Generator to run a compact industrial VFD (Sinamics V20)

I have a Siemens Sinamics V20 (0.5HP) industrial VFD (as picture), powering a 3-phase 0.25 HP electric motor. I work in the field and generator is the only way to have electric power. I am looking for ...
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1 answer
79 views

Why AC motor driver shorts out?

I have been working in a VFD using an AC motor driver FSBB30CH60DF and making control of it using a dspic30f4011. As you can see in the attached circuit schematic, the mains supply is a single phase ...
3 votes
3 answers
265 views

Replacing a 3-phase speed-varying drum switch with a VFD?

I am working on a stock feeder / power feeder (used with woodworking equipment). It has an 8-position drum switch to control both fwd/reverse direction as well as vary the speed. The ON positions of ...
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3 votes
1 answer
601 views

Controlling the speed of a single phase 4-pole induction motor

I have a Crompton Greaves single phase induction motor that powers my drill press (image below). I believe it’s rated at 1/2HP. I wanted to control the speed of this motor so that I can use the drill ...
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3 answers
2k views

Benefits of using a sine wave filter with variable frequency drive

Sometimes sine wave filters are installed on the output side of a variable frequency drive (VFD.) My understanding is that these filters are advised in situations where there may be capacitance among ...
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3 answers
131 views

Motor voltage and VFDs

Is it possible to use a motor with a lower voltage rating than the line input to the VFD that it's running on? Most VFDs have a parameter to set the maximum motor voltage, what effect does this have?
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1 answer
107 views

What Happens if Uncharged VFD is Connected to Charged DC Bus

if the dc fuse of the uncharged drive is closed when the dc bus of other drives is charged , what happens ? Is there any risk of damaga capacitor ? As I know, capacitor can stand to very high currents ...
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2 answers
212 views

Why it is required to fuse each inverter in common DC bus

I have four variable-frequency drives (VFDs) in total supplied from one largest VFD in system. The other three VFDs don't have connection to ac grid. These three VFDs are supplied from common DC bus. ...
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276 views

YL620 VFD terminal strip is small - wires are big. Connector options?

I'm attaching input power (240V single phase) and motor load (3-phase, variable frequency) wires to a terminal strip of a Variable Frequency Drive controller (YL-620). The power rating for the device ...
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217 views

VFD max current rating less than motor peak current - problem?

Whats the worst that could happen if using a QUALITY 8amp VFD - single phase input, 230v, vector controlled - on a industrial 3 phase motor with peak current rating of 50 amps. Do VFDs have the ...
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2 answers
455 views

3 phase motor VFD frequency / current draw help needed?

I am planning to covert a 1920 Drummond B type lathe to 3 phase motor / VFD combo and am trying to understand the math involved with VFDs mainly relating to frequency and current draw. How do they ...
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-1 votes
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234 views

Help choosing 3 phase motor and VFD for mini lathe project

I bought a 101 year old mini-lathe (Drummond B type) and from what I've seen and read online it should be possibe to bring this lathe into the 21 century. In my most extreme vision I would like to ...
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70 views

How can i choose the right VFD for an electric motor?

I have a 1.5kW three phase electric motor that is in a delta configuration. This motor has a motor voltage of 230/400V and a rated current of 5.9/3.4A. What sort of VFD should i be looking for that ...
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Use closed loop torque control based on motor position to simulate a dynamic load

The goal is to use servo + gearbox to simulate a screwing process millions of times. A screwing process is characterized by a low torque at first (the screw enters the material) and once the screw ...
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2 answers
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Table jitter on 40 ft planer mill at certain low feedrates with new 40 hp 3-phase motor and 50 hp ABB drive

The display on the drive shows 26 amps with little variation at all speeds. At 176.14 RPM it shows -9.2% motor torque, 25.63 amps. At 977 RPM it shows 26.04 amps and 2.4% torque. The motor spec ...
1 vote
1 answer
154 views

Induction motor 'droop control' on multi-motor coupled loads

When using droop control to balance the torque across multiple motors driving a coupled mechanical load such as a chain conveyor, what is the actual variable that is being altered by each drive? From ...
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8 votes
3 answers
1k views

Why do variable frequency drives (VFDs) need so much information?

I'm an electricians apprentice at a mine. I understand the basic operation of variable frequency drives (VFDs), rectification, filtering, and pulse width modulation. But, at the heart, all they're ...
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1 answer
390 views

Pole counts for VFD driven induction motor

What is the significance of pole count of IM if it is driven by a VFD? If we are using the power supply frequency (50Hz or 60Hz), the pole counts matter in terms of torque and synchronous speed. But ...
0 votes
1 answer
227 views

What would cause DC bus voltage on my VFD when the disconnect is off

125 hp 480 vac HMax VFD. Controlling a pump motor. Motor is not spinning and line to the VFD is disconnected. I was putting the output wires back on the VFD, when moving the second one into place, ...
8 votes
4 answers
3k views

Can I run a VFD off a generator?

I want to power a three-phase 5hp well pump with a VFD. I want the VFD both to serve as a soft start, and to allow variable speed operation of the motor. Two different pump salesmen have told me that ...
1 vote
0 answers
101 views

Why does reciprocating compressor's motor starting winding have high voltage than running winding

I want to know why the starting winding of (2 ton) reciprocating compressor's motor have high voltage than running winding? I have attached the voltage that I have captured from oscilloscope. This ...
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1 answer
295 views

Building a VFD for a split phase (capacitor run) motor?

I'd like to get variable speed on a very tiny lathe (Taig, 4" swing). I've got a dishwasher motor I'm planning on using for it, which is rated for 3600rpm at 60Hz (it's about 1/5HP). But it's a ...
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0 votes
3 answers
319 views

EMC Cable shield used as PE wire, great idea or not?

In order to save on cabling, our company uses 3 wire EMC cables to connect electric machines to their VFD's. Some folks in our company think we should really use a dedicated ground wire, many are of ...
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1 answer
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How do VFDs limit the starting current of the motor?

I have a 5 HP three phase motor. I am going to install a variable frequency drive (VFD) for speed control. I know that VFDs are used to soft start motors. How do VFDs limit the starting current of the ...

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