Using a variable frequency drive (VFD) can be beneficial in many constant speed applications driven by electric motors, such as those that require controlled starting and have been historically served by a reduced voltage soft-starter (RVSS). While an RVSS and a VFD can both provide a controlled start, let’s examine the benefits of each technology and when it makes sense to use one over the other.
The differences between RVSS and VFDs and when to select one or the other for an application is determined by the following factors (when using a NEMA design B three phase induction motor):
An RVSS can be used to limit inrush current and reduce mechanical stresses on the motor and device it is powering during the starting cycle. The RVSS ramps the starting voltage from 40% (typical) to 100% over a set time (2 - 15 seconds typical). Starting torque is significantly reduced, rising to full torque at rated voltage.
By using an RVSS, locked rotor torque will be approximately:
Rated Torque x 2 x (% applied voltage)2
At a 40% start voltage, locked rotor torque will be:
Locked Rotor Torque = Rated Torque x 2 x (0.40)2 = 0.32 (32% of rated torque)
Because both the voltage and frequency are varied with a VFD, the motor will be at 100% flux at any speed resulting in the ability to produce 100% torque at 100% current at any speed below base speed. Therefore, a VFD can be used as a full torque soft starter in place of an RVSS. When used in this capacity, a VFD is capable of starting loads that require up to 200% torque such as mixers and production machinery with no inrush current.
Parker has recently introduced the AC10 series of general purpose VFDs, available at 230V to 20HP and 460V to 250HP and offer:
Article contributed by Bill Riley, business development manager for the Drives Business Unit, Electromechanical & Drives Division North America, Parker Hannifin Corporation.
6 Mar 2019
For a long time, the use of hydraulic power in industrial processes has been associated with its traditional benefits: high power density, precise control, and long-term performance. Yet these advantages typically come hand-in-hand with equal numbers of potential drawbacks: excess noise, heat generation, and inefficient energy allocation. As we move forward, technologically advanced industrial equipment now requires hydraulic systems that can provide quieter, more economical and more efficient solutions.
Where wasted energy and resulting carbon emissions might have previously been seen as inconsequential, a switch to a tightly-modulated hydraulic system fitted for specific tasks is essential in today’s globally competitive and eco-conscious economy. With various industrial machinery (including die casting machines, presses and plastic injection moulding machinery) placing different demands on hydraulic control, you may wonder: how can highly complex hydraulics systems be adapted for individual requirements?
Matching optimum performance to size requirements
Taking one application example into consideration – injection moulding machinery (used in rubber, thermoplastic and other polymer industries); Parker has developed an immersed servo motor pump system with the aim of enhancing hydraulic reliability and reducing energy consumption. Hydraulics have long been utilised in this industrial process; with a hydraulic power unit (HPU) as the source and with very large capacity pumps and motors to ensure steady performance. However, Parker’s solution brings in three separate elements (a pump, a servo motor and a drive for control) to match flow rate to the particular requirement, primarily through the rotational speed of the motor.
From opening and closing moulds to plasticising and injecting, there are many auxiliary movements – often occurring in parallel – that take place within plastics machinery. They must be supplied centrally with the required flow and pressure over the briefest of cycle times. Controlled by the speed and torque of servo motor as part of Parker’s solution, careful flow and pressure regulation allows for greater energy efficiency. With the high maximum speed of the small vane pump, a very high volume flow can be achieved with the smallest size. Therefore, component size can be optimised to suit their need and investment costs reduced.Selecting a complete solution
Alongside hydraulic systems available for injection moulding machinery, Parker offers a full-system solution, the Drive Controlled Pump (DCP), which combines a versatile range of AC drive controllers, motors and pumps into tailored packages for the most diverse applications. With the incorporation of an alternating current drive controller, the speed range can be set in advance to a predefined cycle. Whether for a long or short duty cycle, the precise amount of hydraulic power required can be calculated for any particular point in time. When selecting between vane pumps or axial piston pumps, factors of output, required minimum and maximum speeds can be assessed and taken into consideration.
Parker’s DriveCreator dimensioning software tool enables the creation of an energy-efficient, speed-controlled, electrohydraulic DCP solution, while its start-up tool simplifies the task of putting the DCP into operation once selected. To discover more about recommended combinations of individual components, please click here.
This article was contributed by Vincent Sinot, key account manager, Parker Sales Company France.
12 Feb 2019
Although the basic recipe for the solid soap bar has not varied much for decades, the process of making this basic commodity has changed significantly since the advent of industrialisation. Modern factories now produce thousands of pieces of soap per day.
Hirtler Seifen GmbH, from Heitersheim, Germany, is one such soap manufacturer, but unlike many of its peers, it has a history spanning over 125 years. From its traditional origins, the company has grown to become one of the largest manufacturers of soaps and cleansing products in Europe, delivering its products to customers all over the world.
However, the company’s plant was in need of an upgrade to optimise its production line for efficiency, production output and recipe-change flexibility. Hirtler Seifen’s 20-year-old digital servo controllers had reached the end of their useful life, and the rest of the system’s associated components could not be upgraded without undertaking a complete system overhaul.The need to increase speed
Automation solution providers Mattke AG from nearby Freiburg were tasked with bringing Hirtler Seifen’s production line completely up to date with the newest precision movement technology. They realised that this was more than just a simple controller exchange task, because Hirtler Seifen’s primary goal was to increase its production rates from 5,000-6,000 bars of soap per day up to 15,000. They also required greater flexibility to accommodate production line changes.
As the plant was already running 24 hours a day, seven days a week, reducing maintenance-related downtime through better equipment reliability and positioning accuracy was identified as one of the ways in which production could be stepped up.
The decision was made to completely replace the linear axles, motors and servo controllers, from the pre- and post-production handling portals to the cooling system for the soap-free cleansing bars. Mattke selected Parker's LBB080 toothed belt linear actuators, SMH-Series low-inertia brushless servo motors and COMPAX3S single-axis servo drives for the job.A four-week deadline
Hirtler Seifen set Mattke a challenging delivery date: the factory was to be closed for just four weeks, during which time the entire refit had to be completed. Throughout this very tight overhaul period, Parker provided essential custom manufacturing support to Mattke.
After the CAD drawings were completed and system requirements were finalised, Parker worked quickly to complete the mechanical axles for the handling portals, complete with electric thrust cylinder, linear actuators, servo motors and drives, in just three weeks – half the time usually required for such a task. During this time, Mattke’s engineers were hard at work setting up the system software. When the mechanical equipment arrived on-site, the team had just one week to install and set up in time for production to begin.Increased production and flexibility
The project was delivered on time thanks to the close collaboration between Mattke and Parker.
“Our partner, Parker, who manufactured the mechanical axles, put in a great deal of effort and provided a high degree of technical expertise.”
Simon Hübner, technical director, Mattke AG
In addition to the significant increase in volume provided by the overhaul, the new system now offers Hirtler Seifen increased flexibility.
Each of the five products that are currently manufactured by Hirtler Seifen can be manufactured at the same time, but still managed separately. And if the soap manufacturer wishes to add more products to the production run, this will be an easy task.
This article was contributed to by Michael Boerner, key account manager, Automation, Parker Hannifin Germany
1 Feb 2019
The renewal of the entire ventilation system in the underground car park serving the largest European business district, was not limited to the simple replacement of filters and some mechanical components. This operation involved a vast project requiring advanced technical expertise, particularly in terms of defining and selecting drive solutions and supporting their integration, installation and commissioning.
The objective of the drive systems for the variation of ventilation speed was two-fold. Firstly, it was a question of ensuring the effective evacuation of exhaust gases. Then, secondly, achieving much faster removal of smoke in the event of a fire. The previously installed system had become obsolete because it was only equipped with two-speed motors without drives.
Parker worked with EDF and Inov Industrie on the project. The company was selected for its technical abilities with respect to drive systems, but perhaps more importantly, for its "know how" in the control of energy consumption/optimisation of energy efficiency. The project presented multiple challenges that had to be overcome. First, the project concerned the most extensive car park in Europe incorporating 22,000 spaces, spread over sixteen different sites. Then, due to the underground location of the car parks, below the towers of La Defense at a complex, major road junction, there were numerous access constraints. To this was added the problem of dimensions: the systems selected had to fit in existing cabinets and be adapted to the protocol already in place.
Enhanced performances at your fingertips
All of the disassembled components being replaced had to be removed and recycled. Finally, and perhaps most importantly, the fire safety system needed to allow the forced operation of the drives at maximum speed in order to reliably evacuate fumes in the shortest possible time. For safety, the new systems also needed to be equipped with an automatic restart and be directly connected to the emergency fire services.
The nature of the project meant that work had to be completed quickly and efficiently under intense time pressure. The scale of the project meant that a total of 60 drives with power ratings from 5.5kW to 180kW had to be commissioned in a very short space of time. Inov Industrie, with its 20-year working relationship with Parker, turned to the motion and control specialist, opting to specify units from the company’s AC10 compact drive range.
Simple and reliable motor control
The suitability of the AC10 range for this significant and challenging project was enhanced due to some new features such as fire mode input/output and its wide range of power ratings - all in a compact package. The AC10 range is characterised by its simplicity of installation, setup, and commissioning, thanks in particular to a fast parameterization. With its enhanced functionality, the AC10 drive is able to control asynchronous motors incorporating both simple and complex types of application such as pressure and flow control. The ‘small sequential’ function (sequencing on and off) avoids the need for an additional PLC. It is also possible to obtain information relating to system power consumption and other parameters such as the occurrence of dirty filters.
Article contributed by Francis Scharwatt, sales engineer, Parker Hannifin France
13 Dec 2018
Maintaining a safe and productive work environment should be top priority in any facility. More and more companies are putting programs in place to improve the working environment and thereby increase the performance of workers.
Audible noise is one of the factors most commonly present on the manufacturing floor, since the operation of any equipment or machinery involves the generation of noise at some level. Usually, the lower the technology of the equipment, the greater the intensity of the noise emitted, reaching in some cases to exceed the tolerable or legally allowed levels.
In addition to the risk of hearing loss, excessive noise has been known to cause physiological effects such as fatigue, tinnitus, lack of concentration and stress, even at levels well below 85 decibels (dB). Keeping people working in environments with excessive noise is a safe bet for reduced productivity and lost time.Corrective actions for noise control
Excessive noise exposure can be mitigated by addressing several elements. The actions for noise control can be classified according to the element on which they are carried out:
Directly reducing the noise generated by the source is the ideal option because it eliminates the need to add elements external to the process and results in a more efficient operation, but can potentially require more initial investment. Among the actions of this type we find:
When it is not possible to act on the noise source, or the reduction reached is not enough, it is possible to alter the propagation medium to reduce the sound effect. These actions have the advantage of being able to be carried out without modifications to the production process, representing a fairly low implementation risk. Among these actions we have:
The noise control actions in the receiver must be the last ones due to the inconvenience that it generates for the worker and the consequential reduction of the effectiveness of oral communication. These actions are typically:
Parker's t-slot aluminum profile system (IPS) is an excellent solution for the manufacturing of enclosure cabinets and noise reduction barriers. The flexibility of the system allows adaptation of the design to the specific geometry of the machine and provides semi-fixed sections that facilitate access for operation and maintenance.
The wide selection of panels allows to have opaque or transparent walls and profiles with double grooves allow the easy fabrication of walls with double panels that increase the attenuation of the noise.
Parker IPS profiles are easy to modify and totally reusable, so you will not only be satisfying your current needs but also future ones. A great way to get started on a Parker IPS project is to download our T-slot Aluminum Design Architect software and start designing today.
To learn more: Visit our website.
Article contributed by Julio Sanchez, IPS product manager, Parker Mexico.
13 Nov 2018
Throughout the world various types of metrology applications share a common need for increased precision. Metrology is the scientific study of measurement. Metrology applications take some type of measurement to collect certain data. Markets such as life science, semiconductor and electronics manufacturing rely on metrology instrumentation to ensure their process is completed correctly. The need for precision is further underscored when you realize the samples/products can be extremely small (i.e. human cell) as well as highly sensitive (i.e. touch-screen electronics). Having high precision motion technology is key to ensure the application will be completed successfully.
This blog post will cover the basics of metrology applications, but if you are interested in learning more, Parker has published a detailed white paper on the topic, which we encourage you to download here.Metrology applications
Listed below are some examples of metrology applications by market. Many applications can be used in more than one market as well. For example, all the markets will use some type of microscopy in their process.
There are different types of metrology applications, and each have their own key considerations. This blog post will focus on dynamic metrology.
Errors in positioning are normally specified in terms of the accuracy of positioning and the repeatability of positioning. The actual sources of these errors can occur in three sub categories – linear, Abbe (roll, pitch, yaw) and planar errors. The source for these errors varies and could have occurred during production or while the application is in process. Examples include deflection, friction, bearing and machining inconsistencies and feedback device.
Velocity control relates to the speed of the stage’s motion and the ability to control it. When there is a variation of velocity as compared to the commanded velocity, this is known as a velocity ripple. Velocity control is critical for dynamic metrology applications because if the speed varies throughout the application process, accurate and consistent results will not be obtained throughout.
The best actuator option for dynamic metrology applications requiring high precision and speed is a linear motor driven stage, specifically one with an ironless linear motor. Since the linear motor couples directly to the linear load, backlash, efficiency losses and other positional inaccuracies are greatly reduced compared to screw or belt driven actuators. Also, linear motors typically have a smaller form factor which overall will improve the stiffness and positional errors. Finally, linear motor actuators have the best control of its speed throughout the application.
While maintaining a reasonable commercial cost, linear motor actuators are the only ones that can meet the critical specifications for dynamic metrology applications previously discussed. To confirm this, Parker uses a laser interferometer to measure any potential positional errors. After testing, reports on the actuator’s performance are generated which consistently show that linear motor actuators outperform those with other drive train mechanisms.
Further details on dynamic metrology download the whitepaper, "Understanding Critical Specifications for Dynamic Metrology Applications."
Parker metrology application solutions
Stage stability and velocity control on a linear motor actuator are crucial in order to have a successful dynamic metrology application. With over 20 years of experience in the high technology precision markets, Parker offers the expertise and consulting services to help instrumentation developers optimize the precision of their equipment and their process. These process optimizations will contribute to continued reductions in the customer’s overall spend, while throughput increases. You can learn more about Parker’s linear motor stage capabilities by visiting our website.
Article contributed by Patrick Lehr, product manager for precision mechanics, Electromechanical and Drives Division North America, Parker Hannifin Corporation.
11 Oct 2018