FAQ :: VFDs | How Can I Troubleshoot A Variable Frequency Drive On A Network?

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Engineering technicians have many nightmare stories when it comes to on-site troubleshooting.  In this instance, I was called to help troubleshoot a Closed Loop (Sensorless Vector) Variable Frequency Drive (VFD) on a production line that was so large, it seemed to go so far down the plant, it never ended.

After overcoming the intimidation associated with the sheer size of the line, it became a question of focusing on just the Variable Frequency Drive (VFD) causing the issue.  The maintenance technicians on site not only had home court advantage, but were on the phone with the Original Equipment Manufacturer (OEM) technical support.  Everything on the line ran great, right up to the point where the VFD on the network in question was supposed to start turning a set of rolls.

The VFD was a proprietary brand that was made in Japan with the rest of the machine.  After speaking with technical support from Japan, a list of discrete inputs to the Programmable Logic Controller (PLC) on the network were determined that could be checked.  The maintance guys at this site were pretty sharp so they had already checked the same list twice. It is still good practice when troubleshooting these types of problems to check these discrete inputs.

The problem most have with troubleshooting a Variable Frequency Drive (VFD) controlled by a network is that it seems so intangible.  There are no wires going to the start terminal to throw a meter on.  This VFD, like most others, had a keypad on its front.  These circumstances brought a phrase to mind that was often published on the cover of Love temperature controllers stating, “If all else fails, please read these instructions.”  The customer had a manual on the VFD, looking to the manual is always a good first step to discovering the root of the issue.

When troubleshooting communications between a VFD and a PLC on the network it is necessary to look at the VFD‘s “read only” parameters and look for the answers to these two important questions:

  • Is the Variable Frequency Drive (VFD) getting a run comand?
  • Is the VFD getting a speed referance?

After getting familiar with the keypad, the customer was requested to get the machine running again.  With the information learned from the manual, through the keypad it was determined the VFD was getting a run command and was, in fact, going into run.

However, it was also discovered that the speed reference was running at 0%.  Normally a speed reference on a VFD will run between 0% and 100%.  So in this instance, it was running at 0%.  So the VFD was running great at 0 speed, but 0 speed is not moving.  After discussing it over the phone with the OEM technical support, it had turned out the rung within the PLC on the network turning on the speed reference was not giving the proper speed reference to the VFD.  Now the customer had something to work with and were able to resolve the issue through the PLC.

Keypads can be very useful when troubleshooting Variable Frequency Drives (VFDs) controlled by networks.  Sometimes it is just a question of getting familliar with the way each unique VFD handles network communications.

FAQ :: VFDs | How Do I Test The IGBT Power Section On My Drive?

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One of the more common problems seen in our Variable Frequency Drive (VFD) repair division is the failure of the IGBT (Insulated Gate Bi-polar Transistor) power section modules.

If the Variable Frequency Drive (VFD) is blowing fuses, or the VFD simply is not turning on, the following test may aid you in finding the root of the problem.

A digital voltmeter test can tell if a short exists from the input side of your IGBT power section modules to the output side without having to take the whole VFD apart to inspect them.  An alternative, more costly test is done by simply replacing the fuses that have blown, then turning the power on.  This is costly because if the short exists, after turning on the power you can expect a boom that will hit you yet again for $100.00 fuses. The digital voltmeter test could save money, fuses and the embarrassment of aVFD blowing up in your face.

Digital Voltmeter on Diode Test:

Every AC Variable Frequency Drive (VFD) has a section called the DC buss. This section is the output of the IGBT‘s. The terminals are often labeled DC+ and a DC-. The preliminary requirements to the Digital Voltmeter test include:

  1. Locating the DC+ and DC- terminals on the VFD. They are usually located near the input and output terminals.
  2. Locating your input and output terminals, and if you located your buss already you have found these terminals.
  3. Make sure that there are no input or output leads connected to the VFD because this will effect the readings on your meter.

Now that the right terminals have been located, proceed with the following steps to test the IGBT power section:

  1. Turn the voltmeter settings to Diode check. It looks like this  ->I-
  2. Take the positive lead on the voltmeter and put it on the DC- terminal of the VFD.
  3. Now take the negative lead and put it on each input and output terminal of the VFD one at a time.
  4. If a terminal is good, it should return anywhere from a 0.299 volt to a 0.675 volt reading on the meter.
  5. Now repeat the same process the opposite way.
  6. Take the negative lead and put it on the DC+ terminal.
  7. Now take the positive lead and put it on each input and output terminal of the VFD.
  8. Again, one should expect the same readings as in step 4.
  9. If the meter returns a reading of 0.000 – 0.100, the IGBT is shorted and needs changed.  These readings could result in blown fuses or even more costly damages.
  10. If the meter returns a reading of more than 0.750, it is possible the contact is open or there could be other devices with issues between the IGBT and the terminal. If this is the case one should contact their local electronics repair shop or contact us during our store hours to resolve the issue.

There are many things that can go wrong with Variable Frequency Drives (VFDs).  The failure of the IGBT power section is one of the most common.  Educating yourself and understanding how the technology works is the first step in saving both you and your company money.  Often times, you will find the electronics repair shop who does work for you will appreciate the preliminary troubleshooting you have done before you called.  This can result in less cost to you and less diagnostics work for them.

VFDs Reduce Energy Costs Up To 60% Using an Industrial Drive

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A properly applied Variable Frequency Drive (VFD) will significantly reduce operating costs.  This is particularly true for variable torque loads such as:

  • Fans
  • Blowers
  • Pumps

Blowers, for example, are often used with dampers to control air flow.  These dampers may be operated either manually or automatically.  When dampers are closed, 50% motor current will drop to approximately 60% of Full Load nameplate current.  By utilizing a Variable Frequency Drive (VFD) in this application, current draw in the motor will be reduced 30% for every 10% drop in speed.  The same motor operating from a Variable Frequency Drive (VFD) at 50% speed will draw approximately 20% of FLA.

An example application:

A 10 HP AC motor rated 90% efficient running across the line with the dampers operating between 50 – 70% for 2000 hours per year will require 11,996 KWH.  If your KWH charge is $.08 per KWH, the cost to run this motor will be: $1,248.00 annually.

The same motor operating from an ASD between 50 – 70% speed for 2000 per year will require 4,676 KWH.  Operating cost at the same KWH rate will be:  $ 432.00 per year.  This represents a savings of $ 816.00 per year and should be enough to pay for the investment into a drive and installation costs in the first 12 months of operation.

If the application operates more hours than in this example and/or the KWH charge is higher the savings will compound very fast.

Reduce Energy Costs Up To 60% Using a Variable Frequency Drive
Reduce Energy Costs Up To 60% Using a Variable Frequency Drive

Another factor to consider is mechanical wear.  Because the motor and blower in this application is running at a lower speed mechanical wear will be proportionally less.  You should also expect less vibration and heat that may affect other equipment nearby.

Most VFD’s will accept a 4-20 Ma input signal for speed reference and control.  Most pressure transducers and automatic controllers can be wired directly into the same control position as your automatic damper.  (also  4 – 20 ma)

The same theory will apply to all variable torque loads.  A variable torque load is one that the load on the motor shaft increases when speed increases, or decreases when the speed decreases.

FAQ :: VFDs | Should I Use An Inverted Rated Motor On VFD Applications?

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Many electricians apply Variable Frequency Drives (VFDs) to AC Motors that are not inverter rated. Many are not even aware that inverter rated motors exist.

Inverter rated motors are not required for inverter applications, however, when a VFD is applied to an inverter rated motor, the inverter rated motor has less chance of premature winding failure. Inverter rated motors have unique windings designed for voltage spikes up to approximately 1500 Volts.

Variable Frequency Drives (VFDs) create artificial sine waves which allow an AC Motor to function; normal AC Motor windings are designed for voltage up to around 600 volts. When these spikes exceed the maximum, the winding insulation starts to break down and eventually will burn up. Inverter rated motors are optimized with higher rated insulated (pulse-shielded) copper windings.

These type of windings can handle voltage spikes up to 1500 volts and higher before the insulation will begin to break down. Inverter rated motors also have tighter bearing air gaps than normal AC Motors.  These tighter air gaps are designed to prevent voltage buildup in the proximity of bearing housings which can cause bearing failure.

The greater the distance the motor is from the drive the more profound the effects of inverter generated voltage spikes.  When the wire from an inverter to the motor is 50 ft or longer, an Inverter rated motor should always be applied.  Always chose an inverter rated motor on new applications.

Operating a Non-Inverter rated motor with an inverter will void the warranty.  When the warranty claim is evaluated by a qualified service shop and/or manufacturer, they will determine the cause of failure to be “Operating of a Non-Inverter rated motor with an Inverter.”

Consult with a professional prior to making a decision on what type of motor to use in your VFD application. Many customers tend to use an existing AC motor for the VFD application if the motor is already available, and replace it with an inverter-rated motor when the original motor fails.  There is some risk in this practice should the failed motor damage your new inverter.

The general lifespan of an AC Motor is dependant on several factors such as:

  • Environment
  • Routine Maintenance
  • Using the correct type of motor and VFD for application.

Many electricians today apply Variable Frequency Drives (VFDs) for numerous reasons on AC Motor applications.  One advantage of using a VFD is to extend the lifespan of an AC Motor. VFDs allow soft-start which in turn creates less wear and tear on a motor, however, if the motor being applied is non inverter rated, some of these benefits may not apply.

This does not mean you should only use a VFD on inverter rated motor only, this just means you have overall greater benefits on inverter motors than basic AC motors.

FAQ :: VFDs | Are There Things to Consider When Operating 50 Hz Equipment at 60 Hz?

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Machinery imported into the United States is often rated at an operating frequency of 50 Hertz. Unless engineered for operation at 60 Hz., this can be problematic for electric motors. This is especially true when operating pump and fan loads. Too often the distributors and purchasers of this machinery assume that the Original Equipment Manufacturer has taken this into consideration. In the repair business we frequently realize this when motors are received for repair roasted out from overload.

A Variable Frequency Drive (VFD) can be used to properly address the issues associated when operating 50 Hz equipment at 60 Hz.

Motor speed is directly proportional to the operating frequency. Changing the operating frequency on a pump or fan increases the operating speed, and consequently increases the load on the motor. A pump or fan load is a variable torque load. A variable torque load varies by the cube of the speed.

A 50 Hz motor operating on 60 Hz will attempt to rotate at a 20% increase in speed. The load will become 1.23 (1.2 x 1.2 x 1.2) or 1.73 times greater (173%) than on the original frequency. Redesigning a motor for that much of a horsepower increase is not possible.

One solution would be to modify the driven equipment to decrease the load.

This may include trimming the diameter of the fan wheel or impeller to provide the same performance at 60 Hz as the unit had at 50 Hz. This will require consultation with the equipment manufacture. Possibly the same manufacture who chose to install 50 Hz rated on a machine to operate on 60 Hz. (your confidence in them should already be suspect). There are other considerations associated with an increase in speed besides the increase in load. These include mechanical limitation, vibration limits, heat dissipation, and losses.

The best solution is to operate the motor at the speed for which it was designed.

If that is 50 Hz., then a variable frequency drive can be installed. These drives will convert the 60 Hz line power to 50 Hz at the motor terminals.

There are numerous other benefits that will be realized with this solution. These benefits include:

  • improved efficiency
  • power regulation (often better than the utility will supply)
  • motor over current protection
  • better speed control
  • programmable output to perform other tasks
  • improved performance.

The same load formula above can be used when speed of a variable torque load is reduced using a Variable Speed Drive. Therefore a 20% decrease in speed will require 58% of the original Horsepower.

 

News :: Industrial | Economy Drives Markets to Seek Online Alternatives

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It has become common knowledge that the poor economy is causing businesses all over the United States to suffer.  As a result of the credit crunch, industrial manufacturing, automation, processing, and other related markets have been seeking alternatives, and found them online.  Historically, industrial markets have relied heavily on the local businesses they have been accustomed to for decades.

The enormous growth of the internet as a form of research and alternative shopping has begun to drive these industrial markets to seek online alternatives.  Many are learning they have been losing thousands of dollars over the past 20 years by seeking no other alternative.  Now many are taking a chance.

“It really is an exciting time,” states Craig Chamberlin, marketing manager of VFDDistributing.com, “many of our customers are reluctant to try alternatives because they assume online businesses will not provide the quality of service they find in their local shops.  Now we have an opportunity to show we’ve stayed successful for 20 years by looking out for our customers.”  VFDDistributing.com offers online drive sales but they are expanding all their services to their online customer base.

Excited, Craig states, “If they give us a chance, we can show them that we are extremely experienced in working in the field and offering extremely competitive pricing.”  Their parent company, Precision Electric, is a one stop shop for everything ranging from Motor Repair to Panel Building and Complete Automation.  All of these services which are made available to the customers they make online.

People are excited about it. Industries such as OEMs, industrial manufacturing, food, wood and steel processing, automation have a new way to cut costs, save time, and have the technical support they deserve. One customer says, “All I did was a google search looking for a particular piece of equipment I was looking for, and many choices came up, it’s definitely a more competitive world out there for our vendors.  If they aren’t paying attention and staying competitive, they are going to lose alot of work.”

There are a long line of reasons customers are seeking internet for purchasing and repair work in the industrial world. Many argue that not only is it the issue of price, but also technical support as well as repair and service work.  Many local vendors have had these customers ‘trapped’ into a corner for so long, local repair centers have lost their excellent customer service and support which they once targeted these customers with.

Precision Electric, Inc. and VFD Distributing is a family owned business that offers excellence in industrial support and service work, and have been doing so since 1984.  Simply inquire for a free quote or if you are in need technical support.


Reading VFD Nameplate Data Off Of Your SMVector Drive (Video)

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For those of you who are familiar or unfamiliar with Lenze / AC Techs SMVector series drive they have come a long way since their conception. All AC Tech products are manufactured in Uxbridge Massachusettes. Today we discuss how to read the nameplate data off of the drive. It is not as complicated as most might think. This is a great way to determine what voltage inputs, frequencies, phases are required and how to determine whether the Variable Frequency Drive itself is an adequate enough size for the motor you want to connect to it. Enjoy!

How-To :: VFDs | How To Access The Terminal Strip Of Your SMVector Drive (Video)

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Thank you all for stopping by.  Today we are going to show you how to access the terminal strip on your AC Tech SMVector Series Variable Frequency Drive (VFD).  This is a basic introduction to the drive itself and for those of you who have not worked with this product before.  You will find doing this is both easy and intuitive – and remember, if you have any additional questions feel free to let us know.  Do not forget, larger drives than the one depicted in this video will have a slightly different layout, but the concept will be the same.

Video Series :: SMVector | How to Land 120 Volts on Your Lenze AC Tech Drive

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In this video we go step by step in showing you how to land 120 volts onto your SMVector variable frequency drive. Ensure you are qualified to handle this electrical equipment before working on it. This process is both easy and painless. The tools you will need are a phillips head screwdriver, wire strippers, your power source leads, wire crimpers, terminal ends and of course, your Variable Frequency Drive (VFD). Feel free to ask us any questions you may have and don’t forget we both service and sell this equipment – you can contact us by telephone at 574.256.1000

Video Series :: SMVector | What is a Variable Frequency (Speed) Drive (VFD)?

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In this video we give you a simplified answer to the question “What is a Variable Frequency Drive”

In the video we use an AC Tech SMVector series drive for an example. Variable Frequency Drives (VFDs) are electronic devices used to control the speed of an Alternating Current Motor (AC Motor).

Variable Frequency Drives (VFDs) are also commonly known as adjustable frequency drives, adjustable speed drives, AC drives and inverters. Variable Frequency Drives have a wide range of application use and operate as load controls within these applications that may accomplish up to a 50% reduction in energy cost.

Thanks for viewing and remember that we sell and service both VFDs and electric motors. You can always call us with any questions at 574-256-1000 or check out our website vfddistrbuting.com for product manuals, frequently asked questions and our Ebay Store.

Video Series :: SMVector | The Lenze AC Tech SMVector Product Overview

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Today’s video is an overview of the NEMA 1 AC Tech SMVector series variable speed drive features, functions and specifications. The NEMA 1 AC Tech SMVector series variable speed drive comes equipped with a large amount of functionality including volts / hertz mode, vector mode, sensorless vector mode and advanced volts per hertz mode. There are a large number of built in features for current and line voltage protections as well as certifications for safety regulations such as UL.

Breaking the Swedish Language Barrier on an Automatic Foaming Machine

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About a week ago, I was given the opportunity to work on a startup with a customer who works in the world of automated foaming. As with any other job, the preliminary overview of the project is often where the scope of the project is determined. One of the most critical things a customer can possess is documentation to their machines, it reduced both the time and effort required on the engineering side of the startup.

In this particular case, however, all of the documentation was written in the Swedish language. The drive itself had extensive documentation in the form of manuals that were written in English, but there were no actual machine documents written in English.

The customer had taken the liberty to do a good chunk of translation regarding the essential documents, but as you know, even documentation written in the English language can be hard to understand if you weren’t one of the original engineers.

On projects such as these, I typically like to spend a day or two with my head completely in the program – in this case with the Google Translator at my side. The two most fundamental aspects I was looking for? The homing sequence and the foam gun sequence (as they desired changes to the way the gun operates).

This is the order of operations I took, and it may help some of you out in the future:

  1. Gather all of the documentation specific to the job.
  2. Gather the requirements of what the customer desires and write them down.
  3. Gather all of the tools that will help you break the language barrier (human translators or robot ones)
  4. Dig out the I/O list if it is included in the documentation (if it is not, build the list yourself manually)
  5. Translate that list to the proper language
  6. Cross reference your I/O list to your documentation to seek out a homing sequence in the program
  7. Use this as your starting point, as your homing sequence is typically the building block of your program.
  8. Next, target the section of the program (referencing the I/O related to it) the customer wants changes too or is having issue with.

This is an excellent starting point for any troubleshooting of PLCs or Motion Controllers outside of your language barrier.  After two days of research and properly building my own documentation – I was able to get the machine running (not without headaches of course) in about one 8 hour day.

Even though the documentation was in a completely different language, this job would have taken weeks had there been no documentation at all – this truly is a testament to the importance of having documentations for your systems – even if that documentation is in a completely different language.

Craig Chamberlin