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  • Writer's pictureAnubhav Gupta

VFD - Industrial Perspective and utility: 2023

Updated: Mar 1, 2023

Why should Paper Mills select Variable Frequency Drive Correctly?


When it comes to maximizing production at your paper mill, variable frequency drives (VFDs) also commonly called ac drive should be a top consideration. This technology is unique in that it can adjust its frequency to match the speed and torque requirements of the machine tool or other electric drive source being used.

This means that VFDs can maximize output by working with the ac motors in ways not possible with traditional gearboxes. For example, if a motor is geared down for low speed use but needs more power during high speed operations, Variable Frequency Drives will automatically increase their frequency to provide optimal performance.

Variable frequency drive systems can be used to optimize power output for various motor requirements. They work by altering the frequency at which the drive operates, allowing for additional power when needed while preserving efficiency during low-speed operations.


How does a Variable Frequency Drive work?


Variable frequency drive (VFD) technology uses a motor to create the periodic motion of the driveshaft or output shaft. This motion is controlled by an electronic controller that detects changes in speed and voltage on a rotating electric motor stator. The controller then adjusts the power sent to the motor, which causes it to rotate at a different frequency. The internal composition and control panel configuration uses several contactors, transistors, diodes, rectifier and dc to ac converter to generate the desired waveform and Hz.


Variable frequency drive has many advantages over traditional motors and drives. These include:


  1. Reduced power consumption- VFDs use less power than a motor or driveshaft-driven system, leading to energy savings in the overall system.

  2. Improved efficiency- VFDs are more efficient because they can run at a higher speed without overheating, which results in decreased energy costs. Additionally, VFD systems usually have a lower noise level than traditional drive systems due to their low-speed operation.

  3. Increased reliability- A VDF system is much more reliable than an electric motor should I use a VFD?


Find a VFD for your application now!


Variable frequency drive options vary depending on the power needs of your application. Search online or contact a specialist to find an option specific to your needs. The basic conditions which one should be aware off before starting the selection process will involve the type of capacitor installation, present current and voltage distortion, range of the voltage source, minimum and full speed of operation, power quality, tolerance, type of transformer and much more


VFD applications in Paper Mills


The variable frequency drive (VFD) has become an important part of the machinery in many paper mills around the world. Its use is due to its ability to vary its speed according to need, thereby improving operating efficiency and reducing energy consumption. Paper machines equipped with VFDs can operate at a higher production rate than those without them, while also reducing emissions of harmful pollutants.


The benefits of using VFDs in paper mills are clear, but they are not the only applications in which this technology can be beneficial. The following article will discuss how VFDs can be used in other industries to improve efficiency and reduce costs.

A VFD is a variable-speed drive that can be used in electric motors or compressors. They are increasingly being used in machines that require variable speeds, such as paper mills, to improve operating efficiency and reduce energy consumption.

Vfd Advantages over other Speed Control Methods: A vfd offers many advantages when compared to traditional control methods like PWM (Pulse Width Modulation). These benefits include the following:

  • Variable speed operation across the entire range of motor speeds

  • No need for frequency locks/toggles on the frequency converter.


Apart from the above, there are specific process applications wherein not only a PLC or a SCADA is significant but the selection of VFD is equally significant. For Example:


a) Paper Mill machine control

This technology is often found on large commercial printers, where it allows for more precise printing and helps prevent jams in the machine. By changing the frequency of the electric current, VFDs can also be used to create movement patterns that help convey information through textiles or other materials.

Sectional and silent drive systems of paper machine control panels use adjustable frequency to generate desired sine wave. At times common dc bus arrangements are also deployed depending on the application.


b) Power Plant Automation

Adjustable Frequency Drive has been primarily used in industrial settings, such as wastewater treatment plants and power generation plants where high torque variations are common.


Power Plant Control SCADA by www.vrindaautomation.com
Power Plant SCADA


The section which decides overall paper quality, economics of process and the chemical consumptions is very significant to be focussed upon.


Starch and Size Press Automation SCADA by Vrinda Automations Pvt. ltd.
Typical Starch cooking control


Variable frequency drive head box automation is a common method for controlling the speed of an electric motor, especially in industrial and commercial applications.


Headbox control options by Vrinda automations Pvt. ltd.
Headbox Control Display

e) Energy Control panels

A variable frequency drive can control the frequency of an electric motor at which it turns, to match the speed of a rotating object.

Variable frequency drives are used in electric power generation, navigation systems and industrial applications where precise speed control is required. Plenty of applications have come which include material feed conveyors, cranes, loading and unloading systems as well as pump and valve controls.


Working of VFD


Variable frequency drive (VFD) is a power supply technology with the ability to vary the speed of an electric motor in response to variations in load. The VFD uses precision-timed drive belts and pulleys inside a motor enclosure, which allows it to provide variable speed control regardless of voltage fluctuations or current draw. This feature greatly enhances reliability and efficiency by allowing motors to run at consistent speeds under fluctuating loads.


What is the main advantage of using an AC Drive in Paper Mill Control?


The main advantage of using a variable frequency drive in paper mill control is that it can help to improve energy efficiency.

Variable frequency drive technology offers several advantages for paper mill control. One advantage is that it can help to improve energy efficiency. Another benefit of using a VFD is that it can increase the speed and torque of the drive motor, which can be beneficial in cases where high power output is required or where greater speeds are necessary for certain operations in the mill. Additionally, VFDs often offer more precise control over motor speed and torque than traditional drives, which could be useful in circumstances where precision or reliability is important (for example, when operating at very high speeds).

Also, it provides an accurate and real-time measure to control the process parameters.

Variable frequency drive (VFD) is an electric motor control system that uses a variable frequency drive output to vary the speed of a motor in order to control various process parameters. VFDs are used extensively in industrial automation and manufacturing applications due to their ability to precisely control speed, torque, power, and efficiency.


Based on the operational data of VFD, one can know about the machine’s behavior, quality disturbances, and other diagnostic issues.

In variable frequency drive (VFD), the frequency of motor is variably changed in accordance with an input power supply voltage. This type of drive has been widely used in induction motor and brushless dc motor applications. It can be characterized by its high torque and speed, which make it a versatile drive for various mechanical tasks. However, VFD also poses certain inherent problems that need to be controlled in order to provide reliable service over extended periods of use.

This article will focus on three key areas: machine behaviour, quality disturbances, and diagnostic issues associated with VFDs.


Application considerations - duty rating, continuity, and control accuracy

1. Duty rating: VFDs are typically rated at 10,000 or 20,000 hours and the control accuracy is usually ±5%. The duty of VFD defines how much current inrush can it withstand, how the microprocessor behaves, what is the range of frequency handles in Hertz, what is the operating voltage range and several other factors.


A variable frequency drive (VFD) uses a motor or generator to produce an alternating current that drives an electric shaft. The voltage of the AC varies in accordance with the frequency of the input voltage, providing movement for an electric motor or another device. VFDs are typically rated at 10,000 or 20,000 hours and control accuracy is usually ±5%.


2. Continuity: VFDs must have sufficient continuity to ensure that power flows continuously from the source to the motor/gearbox.

This is typically ensured by laminating the vfd in series with other components, such as the motor/gearbox.


3. Control accuracy: The controller must accurately monitor input variable frequency drive speed and voltage parameters to maintain desired output speed and torque levels

Controller design: The variable frequency drive controller must be designed to maintain speed and torque levels at a desired level even in the event of an unexpected power loss.


AC line harmonics - side effects of Variable Frequency Drive

Variable frequency drive (VFD) systems present AC line harmonics in the power supply. Harmonics can cause interference, heat generation and noise.

To reduce harmonic interference in power supplies, variable frequency drive systems use pulse width modulation (PWM) to control the speed of the motor. PWM reduces harmonics by cycling the power supply frequency faster than the motor speed.

Harmonic presence can cause various issues in the production line by resulting in unexplained tripping. Thus, resulting in lowering production. This happens for various reasons.

One reason can be that the drive is a frequency variable, which means it changes its speed on a regular basis. This can cause problems because when something switches speeds suddenly, it causes vibrations and shocks in machinery.

Another reason could be that the drive is not properly secured. If it's not held in place well, it can vibrate and cause problems.


Dynamic braking – a requirement of paper machines.

There is a requirement for variable frequency drive in paper machines. VFDs are able to control speed and torque, making them better suited for controlling the machine than traditional belts or pulleys.

There are three types of VFDs- induction, synchronous speed, and stepper motors. Induction VFDs use an electromagnet to create a current in a coil that creates a magnetic field. The motor's stator is connected to the coil and the rotor spins within this field. Synchronous speed VFDs work similarly, but instead of using an electromagnet, they rely on PWM control voltage signals from the controller (inductor or MOSFET). Stepper motors can be broken down into two categories- direct drive and planetary gear-type drive.

VFDs can bear jerks during operation if there is an appropriate selection of dynamic brakes and the attached dissipating resistance.

A variable frequency drive (VFD) is a type of electric motor that uses an electronic controller to change the frequency of its output, usually in response to changes in power demand.

The speed at which a VFD operates can be controlled using dynamic braking, or by attaching a resistive load equivalent to the voltage drop across the motor coils. This allows for smooth and jerk-free operation under normal operating conditions; however, spikes in power demand (due to brief bursts of sudden acceleration or deceleration, for example), can cause sudden jerks in speed if there is inadequate resistance attached.

Braking causes the generation of DC power and fluctuations in DC Voltage which may hamper power factor temporarily.


Regenerative drives - need of Paper Mills for Energy Efficiency

Variable frequency drive (VFD) is a type of electric device that uses a variable frequency power supply to achieve motor speed regulation.

The inverter controller regulates the voltage and current delivered to the motor through an electronic control loop, which in turn maintains or adjusts the delivery frequency in order to maintain constant torque output over a wide range of speeds while minimizing energy consumption.

As VFDs become more common due to their energy-efficient capabilities they are becoming increasingly popular for use in paper mills as opposed to traditional induction motors because induction motors produce significant amounts of noise and vibration when operating at high speed.

To reduce the noise and vibration produced by a VFD, it is common practice to use a variable frequency drive. A variable frequency drive uses an electric motor controller that can change the speed of the electric motor in response to feedback from sensors that monitor vibration and noise levels. By adjusting the speed of the electric motor, it is possible to control these levels so that they are lower than would be producible with a traditional induction motor.


People Also Ask:


Which make of VFD is best suitable for my process?

There is no definitive answer to this question as the best variable frequency drive (VFD) for a given application will depend on a number of factors including the type of process being operated, motor specifications and voltage requirements. That said, some popular VFDs used in industrial applications include synchronous speed drives (SSDs), ac induction motors and dc geared mills.


Should I use a heavy Duty VFD or AC Drive?

There is no definitive answer to this question as different motor applications will call for different frequency drive designs. Factors that may influence the selection of a VFD include power requirements, speed control needs and noise levels.

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