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.
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.
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
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
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.
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.
When it comes to gearbox test rigs deployed in the automotive and aerospace industries, one thing is certain - there is no margin for failure. A test rig or system that is unreliable or produces erroneous results can have serious consequences to development programmes where designers and research and development engineers are under intense pressure to deliver next-generation solutions to a demanding customer base.
Gearbox test rigs come in many different configurations, depending on the type of transmission being tested. However, most share a common requirement, namely the need for electromechanical components such as high-speed servomotors, inverters and linear motors.
A case in point can be seen at BIA, a French-based industry leader in the design, development and manufacture of test equipment and systems for customers in the aerospace, industrial and automotive sectors. The company has been collaborating with specialists at Parker for a number of years, with the outcome that BIA is now able to combine specific elements and components of its test rigs into completely bespoke, integrated systems that offer higher reliability and performance.
“We very much benefit from Parker’s wide product offering that helps us to efficiently source high quality and reliability components and systems, which finally contribute to BIA’s global success. We appreciate the very constructive spirit with which the dialogue with Parker is conducted."
Olivier Carlier. project leader at BIA
Parker works closely with customers such as BIA to help define the components required for each individual simulation and test system. Here, the company’s extensive portfolio assists in sourcing high quality, reliable products and systems. Products such as Parker’s high-speed servomotors, for example, are adopted widely in gearbox test rigs for the efficiency of their cooling systems, as are Parker linear motors, chiefly as a result of their positioning accuracy.
Beginning with Parker’s brushless, permanent-magnet, high-speed MGV servomotors, these offer the capability to simulate a combustion engine in conjunction with a vehicle’s manual gearbox. Of particular note, MGV motors benefit from water cooling, which in turn permits their dimensions and operating noise to be minimised. Furthermore, the low inertia of the MGV allows for highly dynamic acceleration and deceleration, while in order to achieve maximum precision, motor speed and torque are controlled in a closed loop, permitting the servomotor to be used for simulations in both urban traffic and race conditions.
Parker MS asynchronous motor are also popular for gearbox testing applications. The reason stems from the fact that the MS can deliver 10,000 rpm at 500 kW, which is ideal for gearbox duration testing – a task which requires a constant, medium speed without acceleration.
On the subject of transmission endurance tests, Parker ETT linear motors are often deployed (including at BIA) to actuate the gear lever and engage gears. Here, the rectangular rod configuration connected to ETT cylinders simulates movement through the standard H-slots of the gear lever. ETT linear motors have a high positioning accuracy of 0.5 mm, along with repeatability of 0.05 mm.
Also worthy of mention, Parker AC890 inverters have been developed to achieve optimum performance levels with both asynchronous motors (MS) and synchronous servomotors (MGV), and are able to operate in both motor and generator modes. This functionality can be exploited during gearbox tests: one motor can be connected to the gearbox input, just like a diesel engine, while two other motors (operating in generator mode) can be linked with the output of the gearboxes to simulate rotating wheels. This power generation gives full grid energy recuperation and can enable significant energy savings too.
Article contributed by Michel Finck, market development manager, Electromechanical & Drives Division Europe.
Modern Swiss-type lathes have evolved from simple screw machines to high-precision, high-production machines and are now widely used across many industries to completely machine small parts, even for complex operations where no turning is required.Space and cost saving
Whereas a conventional CNC lathe has two, three or four axes, a Swiss-type lathe is an entirely different proposition having up to 13 axes. This makes it possible to machine highly complex components in a single set-up, compared with multiple set-ups using conventional lathes. So why not apply this thinking to a multi-spindle Swiss-type lathe? After all, such a strategy would multiply the benefits in proportion to the number of additional spindles deployed. While this statement is true enough, more spindles means that space becomes a premium commodity which demands clever design and compact spindle motor technology. After all, in a highly competitive global marketplace, every square metre in today’s manufacturing shops carries a cost.
One machine tool manufacturer, however, has found a way around this issue. When Tornos, a leading specialist in Swiss-type lathes, wanted to bridge the gap between single-spindle and multi-spindle machines, it turned to Parker’s permanent magnet synchronous motor technology to reduce the amount of space required to position components and cutting tools and, in so doing, increase productivity in the next-generation design of Swiss-type lathes.
Equipped with eight spindles and eight slides for main operations, and accommodating up to three tools per slide, the Tornos MultiSwiss 8x26 features eight SKW frameless spindle servo motors from Parker and fast barrel indexing for producing turned parts up to 26mm in diameter. Each of the 11kW motor spindles is equipped with a C axis and counter spindle. Reaching speeds of 8,000 rpm in tenths of a second, the motors make a major contribution to performance and productivity, as well as space economy.Direct drive solution for higher productivity
Comprising two separate elements (rotor and stator), SKW motors are integrated directly into the mechanical structure of the MultiSwiss. Compact, reliable and highly dynamic, the motors offer constant torque capabilities over a wide speed range with very small dimensions. Indeed, the space-saving design gave Tornos the flexibility to fit eight spindles into the MultiSwiss without sacrificing any of the high-precision benefits that come with permanent magnet synchronous motors.
As part of a collaborative, partner-based project, Parker supplied Tornos with a complete bespoke spindle motor solution, including a cooling system and sensor equipment. Parker’s long-standing relationship with Tornos has existed since 2005 and received the following endorsement:
“With the high-performance output of Tornos’ machines in mind, the quality and reliability of Parker’s solutions make the collaboration a good fit. We appreciate the close cooperation in terms of both commercial and technical aspects. We also benefit from Parker’s strong commitment with regard to after-sales support and enjoy the close contact and cooperation with their research and development department. Over time, this has meant Parker has turned out to be not only a reliable supplier but also a trustworthy partner.” Bertrand Faivre, Engineering Manager R&D at Tornos
To find out more about the latest Parker spindle motor solutions for machine tools, please click here.
Article contributed by Michel Finck, market development manager, Electromechanical & Drives Division Europe.
In radiographic tilting beds the table upon which the patient is placed needs to be moved and controlled with smooth precision. In this type of application, servo motors and drives play a key role.
Fluoroscopes, angiograms and other radiographic applications can be achieved by obtaining a series of individual X-ray images that are then stitched together or animated to create increasingly detailed imagery that is suitable for expert medical analysis.
In addition to utilising advanced computer software to process the high-resolution radiography imaging, the table upon which the patient is placed needs to be moved and controlled with smooth precision – often over a wide range of angles and positions.
Servo motors and servo drives can be utilised to assure the safe and smooth movement of medical patients.
Reliable, precise movements
For upper and lower gastrointestinal barium enhanced studies, the table needs to smoothly tilt the patient from a horizontal position right up to a vertical position. This movement allows the liquid to flow through the patient’s digestive system while being captured in real time by the fluoroscopic X-ray source.
Each movement of the bed must be engineered to facilitate optimal operator use, to ensure maximum patient safety and to prevent extraneous patient movement during the examination.
The servo motors and drives solution
Each bed is equipped with six Parker SMB low-inertia brushless servo motors ranging from 3 to 10 Nm, with four of the motors equipped with a holding brake for additional safety.
In addition, six SLVD-N servo drives ranging from 5 to 10 A receive command signals from the controller, amplify the signals and transmit current to the servo motors to produce the precise range of motion, torque and positioning required.
The first servo motor controls the up-and-down motion of the table for easy patient access, enabling the table to be lowered to a minimum of 43 cm above the ground, the lowest of its category. The second motor allows the table to move transversally up to 30 cm outwards. The third and fourth motors meanwhile, control the oblique projections of the X-ray source. The fifth servo motor controls the movement of the column holding the X-ray source, allowing it to extend up to 180 cm from the table surface. The sixth and final motor controls the tilting motion of the table, enabling a full 90° range of motion for fluoroscopy and other radiography applications.
Working closely with experts from Parker, the manufacturer was able to improve the reliability and movement repeatability versus the previous solution used.
“We have chosen Parker because of their reputation, quality and the reliability of their products. Furthermore, thanks to Parker’s innovative technologies, it has been possible to constantly improve the performance of our machines. Partnering with Parker is profitable, in terms of both the technical and commercial support provided with the ultimate beneficiaries being medical staff and of course the patients themselves.”
Ing. Alessandro Biasini, R&D project leader, CAT Medical Systems
Learn more about servo motors here.
Article contributed by Michelangelo Matullo, automation account manager, Central South Italy, Electromechanical & Drives Division Europe.
Hazardous locations are operating environments in which explosive or ignitable vapors or dust are present, or are likely to become present. It is normal for various processing applications where gas, liquid or dust will be present in enough volume to cause an opportunity for them to ignite and cause a fire and/or explosion. An example would be an automated paint spray booth where the vapors in the air would ignite from a spark, or from a motor’s surface temperature that was too hot. In such environments, special motors are needed to ensure that any internal fault in the motor will not ignite, or be a source of an ignition.
A risk assessment must be taken to classify potentially dangerous locations as hazardous environments. Equipment and materials must also be suited for use in these dangerous areas. Learning the commonly used terms and design criteria used to qualify equipment will simplify your specification process.
This is important to know and understand so that if your processes are defined as creating a hazardous environment, you can take the steps necessary to specify the correct equipment into your facility that will not create the potential for people to be injured or killed; or for damages to occur from using this equipment.
To keep this information on explosion proof motor classifications by hazardous locations handy, download our whitepaper.
Explosion proof requirements for servo motors are dictated in the United States by UL674 and in Europe under the acronym of ATEX. The following provides definition to the terms that are commonly used within each of the directives. Thereafter, information on the design criteria used to qualify equipment for use in these hazardous areas.UL674
Under UL674 directive, hazardous locations are those areas where fire or explosion hazards may exist due to the presence of substances that are flammable, combustible, or ignitable. These locations break into classes and divisions and further defined by groups and temperature classifications.
Class I – created by the presence of flammable gases or vapors in the air, or flammable liquids, in sufficient quantities to be explosive or ignitable. Class I locations are further categorized by Division (Refer to chart 1) and fall into Group A through D. (Refer to chart 2).
Class II – created by the presence of combustible dust, suspended in the air, in sufficient quantities to be explosive or ignitable. Class II locations are further categorized by Division (Refer to chart 1) and fall into Group E through G. (Refer to chart 3).
Class III – areas, where there are easily ignitable fibers or flyings, are present. These include cotton lint, flax, and rayon as examples. The fibers in a Class III area are not likely to be in the air but can collect around machinery or on lighting fixtures. A Class III location can be categorized as Division 1 or 2.
Relate to the Minimum Ignition Energy of the flammable substance and the location where it is installed. The lower the ignition energy required to ignite the gas, the more dangerous the environment.
Chart 3: Dust groups
Temperature classification – “T-Codes”
The surface temperature or any part of the electrical equipment that may be exposed to the hazardous atmosphere should be tested so that it does not exceed 80% of the auto-ignition temperature of the specific gas, vapor or dust in the area where the equipment is intended to be used.
The temperature classification on the electrical equipment label will be one of the following (in degrees Celsius):
ATEX consists of two European (EU) directives. They are:
Equipment Groups – Broken into group I and II and further broken down by category. The category definition is based on equipment design for protection.
Group I – Intended for use in underground mines as well as those parts of surface installations of such mines that are endangered by fire and/or combustible dust.
• Category M1 – ensures a very high level of protection.
• Category M2 – ensures a high level of protection.
Group II – Intended for use in surface equipment that is, or can be exposed to hazardous conditions (fire or explosion).
• Category 1 – ensures a very high level of protection against gas, vapor, mists, and dust that are present continuously, frequently, or for long periods.
• Category 2 – ensures a high level of protection for use in areas in which explosive atmospheres caused by gas, vapor, mists, and dust are likely to occur.
• Category 3 – ensures a normal level of protection for use in areas in which explosive atmospheres caused by gas, vapor, mists, and dust are unlikely to occur, or would happen infrequently.
Temperature Classes - relate to a flammable substance and its Auto Ignition Temperature.
There are various design criteria that the manufacturer can incorporate into their design. What is chosen will dictate the hazardous environment that the equipment can be used in. There are 4 “General Principles” of protection against explosion. They include:
• Explosion Containment - allows the explosion to occur but confines it to a defined area. A structure cannot fail from the explosion.
• Segregation - a method that attempts to separate or isolate the electrical parts from the explosive mixture. Practices include pressurization, encapsulation, oil immersion, and powder filling.
• Prevention - a method that limits the energy, both electrical and thermal, to safe levels under both normal and fault conditions. Practices include Increased Safety, Intrinsic Safety, Non-Incendive (simplified) and Special Protection.
• Increased Safety – must prevent the possibility of having excessive temperature or generations of arcs or sparks inside or outside the apparatus during normal operation. Accomplished by incorporating an elevated safety factor to all components that make up the apparatus (connections, wiring, the degree of protection of enclosure, etc.).
• Intrinsic - the most representative of the prevention concept and is based on the limitation of the energy stored in an electrical circuit (the circuit is incapable of generating arcs, sparks or combustible thermal effects). Intended for process instrumentation applications where the power required is less than 30 volts and 100 mA.
• Non-Incendive – similar to Intrinsic where the electrical apparatus is incapable of igniting a surrounding mixture during normal operation. They differ in that the non-incendive is not evaluated for safety under fault conditions, so as a result is not approved for Div. 1 environments.
• Special Protection - developed to allow certification of equipment that is not developed according to any of the existing protection methods. Can be considered safe for a specific hazardous location but must undergo appropriate tests and/or a detailed analysis of the design.
By helping operations personnel and engineers better understand the many factors that go into hazardous duty motor selection, the risk of explosions in facilities can be substantially reduced. Understanding the commonly used terms and design criteria used to qualify equipment provides facility managers with assurance that their operations are safe and in compliance with applicable regulations.
If you're uncertain that your servo motor will be safe in the environment in which it must operate, always consult the motor manufacturer for assistance. Never guess when worker safety is at stake.
Learn more about our options in explosion-proof servo motors by downloading our Explosion Proof Servo Motor catalog with complete product specifications.
Article contributed by Jeff Nazzaro, gearhead and motor product manager, Electromechanical & Drives, North America.
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