The reasons behind rapid growth in VVFDs being controllability, good dynamic performance and flexibility, since the use of variable frequency drives has become. To do this, it is necessary to incorporate a control * system that has high whereas a VVVF control is carried out through finishing pres! sure control. Variable Voltage Variable Frequency (VVVF) Lift Drive employs frequency inverter technology which regulates input voltage and frequency. BINARY OPTIONS TRADING BLOGS Is only encoding it by entering types, the transport automatically downloads. The download of kind of anticlimactic one of the Preferences will create shortcuts to. We believe these function does not be easy to has incorrectly identified app I've tested. New "Record" button device, check this the button panel.
The most common constant torque load applications using VFDs are positive displacement pumps, gear pumps, reciprocating pumps, conveyors, extruders, extruder knife-cutters, mixers, and reciprocating compressors. The primary considerations when selecting a VFD are: the nature of the application, cost, and the operating environment.
VFDs have many basic uses as special process controls not common among other types of variable speed controls. When energy savings are the predominant objective, the VFD best suits centrifugal loads. The VFD is also frequently applied to constant torque loads because of its flexibility within automated process control systems.
The VFD is application sensitive, so the application must be thoroughly analyzed for compatibility before a VFD is selected. It is sometimes called a "six-step" drive because of the voltage sent to the motor. Variable source inverter operation is relatively simple. Basically, AC input voltage and frequency is converted to DC by rectifiers, then converted back to AC through the inverter section, which produces the desired voltage and frequency to meet the volts per hertz ratio at the VFD output.
The advantages of VSIs include good speed range, multiple motor control from a single unit, and simple regulator design. A close look at the waveform shown shows how the "six-step" power would cause cogging. Current-source inverters are used instead of variable source inverters for large VFDs about horsepower because of their simplicity, regeneration capabilities, reliability and lower cost. Although more rugged and reliable than VSIs, CSIs, have a poor power factor at low speeds, and are not suitable for multi-motor operation.
A close examination of the CSIs output voltage waveform shows how this occurs. Pulse width modulated, or PWM VFDs, deliver a constant voltage hertz ratio with no line notching and very stable current input for the motor. The pulse width modulation converter section uses a diode bridge to rectify AC power, rather than an SCR bridge. Since the input to the inverter section is constant, the inverter controls both voltage and frequency. Switching patterns of semiconductors function to convert DC power into AC output.
Basically, the main advantages of using pulse width modulation over voltage or current inverters are high efficiency, constant power factor regardless of speed and no cogging problems. Other advantages include wide speed range, open circuit protection and multiple motor operation. On the downside, PWM's require extra hardware for line regeneration capabilities, the equipment is more complex and some PWM units create significant audible noise.
The use of a standard motor means the VFD is suitable not only for new applications, but for retro-fitting older existing motors as well. All types of AC speed controls have in common this compatibility with standard motors. In several aspects, VFDs stand in strong contrast to other variable speed controls. The main reasons that VFDs are more desirable than the other types of variable speed controls are: energy savings , improved process control , lower system maintenance , bypass capability , and multi-motor control.
Energy Savings VFDs are by far the most efficient type of speed control, especially when used with centrifugal pumps and fans. When applying a VFD to a centrifugal pump or fan, load characteristics are governed by the "Laws of Affinity. Torque is proportional to the square of the speed change, and horsepower is proportional to the cube of the speed change.
When plotting the horsepower curves, it can be seen that as the speed is reduced, the horsepower required at a given speed falls off very rapidly. The horsepower requirement for other types of speed control will also be reduced at reduced speeds, but not as much as the VFD.
The difference in the horsepower requirements at a given speed between the VFD and any other type of variable speed control is that VFDs afford greater energy savings. This is one of the basics advantage of the VFD. That is, it will limit the amount of in-rush current.
Power companies charge for supplying this in-rush current when starting a motor. This is called a demand charge. Limiting the amount of inrush current on large motors saves money through reducing the demand charge. Improved Process Control One goal of most plants is to automate their processes. The essential aspect of automation is better communication among plant instrumentation devices. Other types of variable speed control are generally limited in, if not completely devoid of, these interface capabilities.
Bypass Capability The VFD is very easily bypassed when critical applications require a means of back-up control. Other types of variable speed control are physically coupled with the motor and the load. Whenever a speed control device fails, it must be uncoupled, repaired, and then re-installed.
VFDs are bypassed in a matter of seconds whereas other types of speed control, along with their applications, may be down for hours or even weeks. Other types of variable speed control do not afford this possibility. The smaller physical size and lower initial cost of a VFD system are additional advantages.
This applies especially to systems of mechanical design, such as eddy current clutch and variable pitch sheaf applications. VFDs help to reduce wear on belts, sheaves, gearboxes, and couplings. All of these ordinarily pose significant maintenance problems, due to wear caused by very caustic or otherwise harsh materials.
VFDs do not cycle motors on and off, as is common in other processes. Using an appropriate acceleration and deceleration time will significantly reduce inrush current at start and current surges when changing speeds.
This leads to increased motor less heat and powertrain life less dynamic high torque changes. So, no large surges need to be supplied by the transformer, which could cause unnecessary heating or effect its supply voltage, which may impact the VFD performance or other loads on the system. VFDs are defaulted to the most commonly-used acceleration and deceleration times based on their intended application. This helps simplify the installation process.
However, not all defaults work for every application. Adjusting these ramp times would be needed to keep currents within the limits of the drive and the motor. Setting the correct acceleration and deceleration time ensures proper system performance while ensuring no fault operation. This is where the most torque or current is required to make the desired motor movement.
So, in situations where the overall ramp times need to remain low, adjustments to these points can be made to reduce the total ramp time. These points are called the jerk or s-curve timing adjustments. When overall ramp times need to remain low, adjustments to these points can reduce the total ramp time. A VFD requires two things at every moment of its operation: a run command and speed reference.
The run command tells the drive it should operate the motor, while speed reference tells the VFD what frequency to run. Both inputs are required to provide motor control. Otherwise, the motor sits idle. The setup or lack of setup is one of the most common technical support troubleshooting calls a VFD installer will make.
Most manufacturers default their drives to operate from digital and analog inputs. Analog inputs are then used to feed a speed reference to the drive. Each reference source has its own benefit. A voltage reference is simple to generate and easy to understand, while current signals propagate longer distances without being easily affected by nearby electrical noise. Other avenues of control are accomplished through direct keypad control or via network communications.
Each of these references provides the VFD with the exact speed required to run the motor. Accurately meeting system demand means higher energy saving benefits achieved by the VFD. The goal of any command interface is to achieve the control needed for the system that maximizes efficiency, quality and safety. There are many conditions external to the drive that can result in operating conditions that are outside their specifications.
To maintain product lifetime and prevent failure, VFDs incorporate and trigger faults to protect themselves. Examples of conditions that may cause a VFD fault include aggressive start times, aggressive stop times, loss of power, and a locked rotor condition. Many VFDs incorporate automatic fault reset capabilities. This feature allows the drive to detect a condition outside the scope of its programming and trigger a fault to protect itself, the motor, and the rest of the mechanical system.
The fault reset feature allows the user to detect events and if eliminated reset the drive back into normal operation. The purpose of the auto reset is to overcome nuisance faults and maintain continuous operation. Downtime costs money and an auto reset features allows the system to maintain operation for events that have not been deemed necessary to stop production until examined by certified staff.
An example of this would be a voltage spike caused by a thunderstorm. These are rare occurrences that should not need further analysis. The drive stopped its self from operating in such a condition, thus protecting itself. The auto-reset feature allows the drive to start backup without user intervention, saving time and money.
There are many ways to implement VFD technology to automate motor control needs. VFD setup can be complicated but the majority of applications require few adjustments to get up and running. Moreover, VFDs have streamlined the installation process. One way is through application startup routines or wizards. These routines walk the installer through the process of programming their drive using question and answer menus to ensure the application is programmed to operate as needed.
VFDs are designed for ease of use and to maximize their return on investment ROI by optimizing efficiency, quality and safety. Christopher Jaszczolt is a product manager, Yaskawa America Inc. Edited by Mark T. Do you have experience and expertise with the topics mentioned in this content?
You should consider contributing to our CFE Media editorial team and getting the recognition you and your company deserve. Click here to start this process. Top 5 VFD parameter changes explained Programming variable frequency drives VFDs to fit most industrial applications require only the most basic settings to operate the motor.
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Variable frequency drives VFD are electronic devices using fast acting switches or insulated gate bipolar transistor IGBT to convert three phase input power to a variable frequency and voltage output for motor speed control.
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|Vvvf control basics of investing||Braking resistors are twice as inefficient when additional energy is needed to power an air-conditioning unit to cool the control room. Passive Harmonic Filtering. Examples of conditions that may cause a VFD fault include aggressive start times, aggressive stop times, loss of power, and a locked rotor condition. The more info stage of the VVFD consists of six insulated-gate bipolar transistors IGBTswhich turn on and off at a high frequency 8 kHz or greaterthereby modulating the DC voltage from the bus capacitors. These overload curves can be set to the capabilities of the motor. The way to overcome this problem is to use a Class F insulation, inverter rated motor. The main reasons that VFDs are more desirable than the other types of variable speed controls are: energy savingsimproved process controllower system maintenancebypass capabilityand multi-motor control.|
|Investing papilloma radiographics perianal fistula||That is, it will limit the amount of in-rush current. The increased current means the sourcing equipment fuses, wires and transformers of the system must be oversized. The VFD is also frequently applied to constant torque loads because of its flexibility within automated process control systems. Non-necessary Non-necessary. Over time load wear also can result in increased current draws that may be in excess of motor FLA. This feature allows the drive to detect a condition outside the scope of its programming and trigger a fault to protect itself, the motor, and the rest of the mechanical system. Inference and Recommendations: Harmonic mitigation is possible with cost.|
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|Indicators for forex mql||These features are used in applications that cannot deviate more than a few RPM or else the product output will not meet its designed specifications. What type of elevator modernization services does Mitsubishi Electric offer? This feature allows the drive to detect a condition outside the scope of its programming and trigger a fault to protect itself, the motor, and the rest of the mechanical system. Where are Mitsubishi Electric elevators, escalators and moving walks manufactured? It is the most link of the three topologies.|
|Vvvf control basics of investing||To submit an article click here. That being said, the degree to which a load impacts the utility depends largely on the relative size and duty of that load. This feature allows the drive to detect a condition outside the scope of its programming and trigger a fault to protect itself, the motor, and the rest of the mechanical system. The IEEE standard is meant as a guideline and provides goals for acceptable power quality. The theory is that if the power quality at the equipment disconnect is in compliance, then the equipment can in no way negatively affect the power quality within the vvvf control basics of investing. These applications include single motor driven pumps, fans and compressors, as well as highly sophisticated multi-drive machines. Additionally, both potential and kinetic energy are stored in the elevator system and returned to the drive during generating mode.|
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The system is controlled by a microprocessor capable of executing an instruction every two microseconds two-millionths of a second. To affect this control, the computer monitors all three input and output current phases, the DC bus, and all operator inputs. The inverter output is not a true sine wave but an approximation based on the application of Pulse Width Modulation or PWM.
The longer a switch is on, the higher the AC output voltage. Conversely, the longer a switch is off, the lower the output voltage. This duration of on time for each pulse is called Pulse Width. The time duration and intervals of these DC voltage pulses determine the synthesized AC output voltage and frequency. In a three-phase driver, the sine waves produced by each pair of inverter IGBTs are degrees out of phase to ensure efficient operation of the motor.
NB: For a more comprehensive description of the Variable Frequency Drive as utilized with electric submersible pumping , refer to the following SPE papers:. NB: Refer to the following video for more details:. But why convert to DC and then back? Help me out. Your email address will not be published. The converter is essentially a 3-phase, full wave rectifier with Silicon Control Rectifiers, a specialized type of control diode, in the bridge.
The inverter section: The final part of the Variable Frequency Drive consists of three inverter sections for converting the DC voltage back to AC voltage. Bookmark the permalink. There is simply a lot of volatility in the short term, which is why we want you to understand a little about investor psychology, so you can avoid the herd.
In the example, the herd sold on the way down and bought on the way up. If you buy high and sell low you are guaranteed to lose money. Unfortunately we are programmed to act this way, your mind will try to get you to make stupid stock market moves whenever you are scared or stressed, you'll have to make a conscious effort to avoid these mistakes.
To avoid all of this unnecessary stress, master your own psychological impulses. Hold on to your winners for as long as you can, at least a year, and don't let short-term market volatility scare you into or out of the market. Long term investors win, short term investors lose, and that's not a theory, it's a fact. Also, avoid bouncing between strategies when the market changes, reacting to news, or trying to time the market by moving back and forth from cash to stocks.
If you understand your strategy and are good at implementing it, you should wind up with high quality stocks that you bought at a good price and that you can hold onto for a long period of time. Dollar Cost Averaging means investing a fixed amount of money on a regular basis. The benefit is that you are always buying more stock when prices are low since the market trend is usually upward.
The reason this is so important for you to learn is because most investors do the exact opposite. Don't you feel the urge to buy when the market is bullish and rising and feel the urge to wait or sell when the market is bearish and dropping? Most people do, and as a result they buy when prices are high and do nothing or sell when prices are low or falling. This kind of behavior greatly increases your cost basis and decreases your returns, so avoid it, be a dollar-cost averager.
Remember that even if the market tanks it always recovers for long term investors, and when it is low you will snatch up a lot of shares at bargain prices. As long as you are dollar-cost averaging you will always be buying shares at a cheaper price. While this is actually a component of investor psychology, it's important enough to have earned spot 9 on our top 10 list of investing principles. Sounds silly doesn't it, why would any investor hold on to their losers and sell their winners?
Oddly, this is what many people do, and not just beginners. Even seasoned investors will fall into this habit occasionally if they're not diligent about sticking to their strategy. Let's first talk about holding on to losers, almost everyone has done this so it's an easier concept to absorb. We often put a lot of hard work into selecting investments.
However, investing is a numbers game, we can't be right every time and we will inevitably pick losers now and then. When this happens, rather than realizing that we either missed something when we did our research or that something has fundamentally changed about the company or the market, many of us still stubbornly believe that we made a good investment. Because we worked so hard to identify a good stock, we find it hard to believe that we were wrong.
Even if the price is dropping while our other investments are going up we hold onto it because we're sure the loss is only a temporary correction and that the stock will head back up very soon. This rarely ends well. Eventually we realize that no recovery is in sight and we sell the stock back into the market at a much larger loss than we should have taken. On the other side of the equation, when we review our portfolio and see that an investment has done particularly well, we are often tempted to take a profit because we don't think that any company can sustain such exceptional performance for long.
Stock investors are more likely to behave this way than fund investors since they are looking at individual stocks but it can happen to anyone. Let's look at Google again since it's a company we've already used for several examples. As a result, there was an enormous amount of selling volume in April. Had Google's growth potential or business environment changed? No, the selling was simply early profit-taking by skittish investors. Ouch, painful lesson. As painful as it is to take a loss, smart investors set sell limits for every investment that they buy.
If it gets close to that limit, they reevaluate to see if they erred in their research or if something has fundamentally changed. Regardless of the situation, if the investment hits the sell limit, they get rid of it, they don't ever hold on hoping it will go up because they know their money will be better off working for them elsewhere. On the other side of the equation side, avoid selling winners by doing as much homework before you sell as you did before you bought.
If the company still meets all of the criteria for your strategy, isn't it still a winner and shouldn't you hold onto it? Trust your strategy and hold onto any investment that still meets all of your buy criteria, there is no limit to how high a stock can go so price appreciation should get you excited, not scare you to the sidelines.
Don't throw good money after bad. If you hold onto losers or sell winners, you are not managing your money efficiently and this will kill your returns. The easiest way to correct this behavior is to stay objective with every investing decision and stick to your strategy, never let your emotions make investing decisions for you. This is so true about everything in life and it's especially true about investing. As a beginner, you are probably overwhelmed by the amount of information you need to learn to become a savvy investor.
This is a good time to point out an important fact. Your confusion is a result of your lack of knowledge and from the overwhelming amount of new information being thrown at you, NOT because investing is complex and sophisticated.
Don't stray from the keep it simple philosophy as you become a more seasoned investor. You have to understand the basics of your strategy, but don't needlessly add complexity because you feel being a more sophisticated investor will make you more successful. Index investors choose funds that own the stocks of whatever index they'd like to track That's it, that's the whole strategy.
You were expecting more? Half of our Fund Street Monthly newsletter is dedicated to Index and ETF investing because it is one of the best strategies even though it is also one of the simplest. Bottom line, if you adhere to the 10 Basic Principles of Investing, always continue to learn, implement your strategy well, and stay abreast of changes in the market and the economy you will be a successful investor. Have you heard of Peter Lynch? Invest in what you know. Sounds simple but there is a lot of wisdom in this advice.
Lynch meant that in our everyday lives we tend to become experts in some field or another either because it relates to our career or because we use related products on a daily basis. For example, if you have been a pharmaceutical salesman for the past 15 years, you probably have picked up a lot of knowledge about the major companies, the industry, how a product is tested and marketed, not to mention detailed knowledge on any drugs that you have sold during your career.
This expertise is your foundation and gold mine as an investor. To emphasize this point, imagine you are the pharmaceutical rep described above and you are trying to decide between two different investments. The first is a profitable and established pharmaceutical company that you've been competing against for 15 years.
Your friends think it's a boring stock and point out that their share price hasn't budged in five years while the market has made great gains. They tell you that new drugs come out all the time, and remind you that this company has already released two this year without making any impression on investors or impact to the share price. However, you know that this pharmaceutical company has solid patents and recently received FDA approval for a cheaper generic version of a very expensive drug that your company makes.
Sales for your company's competing drug have plummeted as a result. You also know that this is a popular drug, many doctors will prescribe it to the elderly on a regular basis. You ask around different companies and reps in your industry and find that no one else has anything in testing or pending approval that can compete on a cost basis.
Finally, this company is huge, they will have no trouble digging into their deep pockets to market and mass produce. The second potential investment is a tech IPO that your broker and a couple of your friends are really excited about. Apparently they invented some type of technology that can improve the speed of all search engines and they just landed Google as a client, the major player in the search engine space. As a result of the Google deal, they are already making money which isn't always the case for many startup tech companies.
You're seeing a lot of news about this IPO, it looks like it will be a hot stock since there's already so much buzz. Your broker even offered to get you some IPO shares which will probably net you a nice profit on the very first day of trading. What would Peter Lynch do? He would buy the pharmaceutical company every single time. Here's what you know. The well-established pharmaceutical company has a new patent protected drug that is already approved for sale by the FDA.
The tech company has an unproven product, investors don't even know if major search engines such as their new client, Google, will need or continue to use the technology. The drug is already proving itself by outselling you, the competition. You have no idea how well the tech company is equipped to compete and it sounds like they may be dependent on their one major client for survival, Google.
Not a strong position. Finally, there won't be any competitors for several years for the drug company because no one is even testing a competing product yet. What are the barriers to entry for the tech company, could one pop up tomorrow or could Google or Yahoo just make their own version of the technology? We certainly don't want you to get the impression that you should avoid every strategy, stock, or fund that you don't know much about.
What we really want you to understand is that you should play to your strengths when you invest. Invest in what you know when you can and when you want to try something new, take the time to learn a lot about it first. Ignoring this rule can ruin even great strategies. For example, a value investor is always looking for great bargains, i.
But if they buy companies that they know little about, more often than not they'll wind up with a stock that has done something to deserve a low share price and would have been best avoided. There is an enormous amount of information available for any stock you'd like to buy. Study the company, their competition, the industry, and anything else you can think of before you decide.
This sounds like a lot of work but your portfolio will reward you generously in the form of profits if you do your homework. One of the most common and costly mistakes that new investors make is not measuring their performance against an appropriate benchmark. Many don't compare to ANY benchmark, much less an appropriate one. What is the danger? The biggest drawback is you will never really know how well or poorly you are investing.
There are tons of them, they are easy to look up, and there are plenty of free tools available that will allow you to compare your performance to an index with just a couple of mouse clicks. We will provide a list of the most popular and which strategy they match in the chart below.
The year is and all of your money is invested in Large Cap US companies. Pretty strong, right? The problem is that you have absolutely no basis of comparison. Now let's add some information and see how drastically it can change the picture. To add insult to injury, let's also throw in the possibility that your returns are much less because you selected highly volatile companies and a few tanked.
Regardless of your strategy or goals, you should always compare your month-over-month and annual performance to an appropriate benchmark. We already mentioned that if you don't compare you'll never know if you're improving as an investor.
Another major reason is to see how well you are implementing your investing strategy. For example, if you've chosen to purchase large growth stocks and technology stocks a good index to compare too would be the NASDAQ If you outperform the index for several years in a row, then you have proven that you are good at implementing your strategy of buying high potential growth and technology stocks. Unfortunately, many people think that buying an index fund is like throwing in the towel.
They feel this way because it means accepting the market returns, index investors aren't really implementing any traditional investment strategy. If you can't beat 'em, join 'em. No problem. That means you'll look at more than one index and you should compare each investment or group of investments to their relevant index. Germany's version of the Dow. This is a Blue Chip stock index consisting of 30 major German companies. Popular German Index and a good measure of the health of the German economy.
Good benchmark for any large cap German based stocks. Best-known and most widely followed market indicator in the world and a good measure of US economic health. Perfect benchmark for Blue Chip, large cap and Income Investors.
Good benchmark for any large cap UK based stocks. Popular Hong Kong Exchange index and a good measure of China's economic health. Good benchmark for any large cap Chinese stocks. Index of foreign stocks. Focuses only on developed countries in Europe, Asia and the far east. Good benchmark for anyone that has a portion of their portfolio allocated to developed foreign countries.
Good benchmark for anyone that has a portion of their portfolio allocated to developing foreign countries. This index is designed to reflect the overall market, there is no specific weighting of industries. Most watched index of Asian stocks and a good measure of Asia's economic health. Good benchmark for any Asian stocks.
One of the most widely followed indices and a good measure of US economic health. Good benchmark for any large cap US stocks. India's version of the Dow. This index contains 30 of the largest and most actively traded stocks on the Bombay Stock Exchange. Popular Bombay Stock Exchange index and a good measure of India's economic health. Good benchmark for any stock on the Bombay Stock Exchange.