ABB drives and motors ATEX compliant low voltage AC drives and motors for chemical, oil and gas

ABB drives and motors ATEX compliant low voltage AC drives and motors for chemical, oil and gas PROFILE INDUSTRIES PRODUCTS APPLICATIONS EXPERTISE PARTNERS SERVICES Profile When an electric motor and an
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ABB drives and motors ATEX compliant low voltage AC drives and motors for chemical, oil and gas PROFILE INDUSTRIES PRODUCTS APPLICATIONS EXPERTISE PARTNERS SERVICES Profile When an electric motor and an AC drive, together with the driven equipment, are installed in a potentially explosive atmosphere, there is an increased risk of an explosion occurring. To tackle this situation, European Union (EU) directives known as ATEX have been implemented covering the Essential Health and Safety Requirements (EHSRs) for products used in potentially explosive atmospheres. ATEX is the French acronym for Atmosphères Explosibles (explosive atmospheres) and is used to describe the application of two directives, covering product safety and worker safety - see page 12 to 15. The importance of ATEX ATEX is not new: it is a group of EU directives to rationalize legislation and increase the harmonization of equipment sales across the EU so that a UK company, for example, can purchase equipment from Germany without worrying about standards in different countries. The objective of Product Directive 94/9/EC (also known as ATEX 95) is to ensure that equipment and protective systems function safely when used in potentially explosive atmospheres. ATEX 95 covers the minimum requirements applicable to mechanical and electrical equipment capable of causing an explosion through its own potential sources of ignition. Directive 94/9/EC is made under Article 95 of the European Treaties and is referred to as ATEX 95. It is intended to allow the free movement, within the EU, of equipment and systems for use in a hazardous area without the need for separate testing and documentation. The Worker Protection Directive 1992/92/EC (also known as ATEX 137) covers the minimum requirements for improving the health and safety protection of workers operating in potentially explosive atmospheres. ATEX 137 also defines the various Zones for gases, vapors and dusts. ATEX 95 and ATEX 137 harmonize the standards and rules for designing, manufacturing, testing, using and maintaining products and equipment throughout the EU. They also establish a framework of certification bodies - the Ex Notified Bodies - who are able to undertake the supervision of products and quality systems. Shared responsibility The installation of electrical equipment in potentially explosive atmospheres used to be a straightforward procedure, requiring only the selection of equipment certified for the appropriate area. However, the arrival of the ATEX directives from the EU changes all that. While the end-user is responsible for installation of products and equipment, the electric motor manufacturer is responsible for safety of the motors and for delivering maintenance and installation instructions. The end-user must define the Zone, the gas group, the temperature class and the preferred protection class. Based on this information, the manufacturer proposes the product/equipment to be used. 2 3AUA REV A EN ABB Profile The impact on AC drives and motors Electronic speed control of AC motors brings a range of benefits to processing industry applications including: soft start precise control of speed and torque significant energy savings optimal process control, removing bottlenecks in production An ATEX approved AC motor and AC drive combination gives safe, economical power combined with effective control. Usually only the motor and driven load are installed in the potentially explosive atmosphere, with the drive being installed in a safe area. By choosing an ABB ATEX package, end-users can be confident that the motor and drive combination is optimized for their application. The package can result in a cost benefit: end-users that choose to match their own drive and motor combinations may be forced to select a larger motor than optimum because of the limited selections available from their chosen manufacturers. Global impact Although ATEX directives are only applicable within the EU, they are based on European standards which has lead to their principles being demanded by users throughout the world. However, ATEX approval is generally not recognized outside Europe and industries with hazardous areas should investigate which approval schemes apply locally. The Zone system divides hazardous areas into Zones, based on the presence of a potentially explosive atmosphere. The Zone system is used all over the world, except in North America. Here, a system of Classes and Divisions is used to denote hazardous locations. The Classes are based on the type of hazard, while the Divisions are based on the risk of explosion that the material presents (see Table 1 below). Both the EU and the US system provides effective solutions for managing electrical equipment (ATEX directives also apply to mechanical equipment) in hazardous areas and both systems have excellent safety records. Some US companies have now established the use of Zoning in their coding to be compliant with ATEX directives and are therefore able to sell products and equipment to EU end-users. Hazardous material Gases or vapors US Class, Division system Class I, Div. 1 Class I, Div. 2 Dust Class II, Div. 1 Class II, Div. 2 EU Zone system Table 1: US system of Classes and Divisions compared to EU Zone system. About this brochure Zone 0 and Zone 1 Zone 2 Zone 20, Zone 21, Zone 22 This brochure aims to give a practical overview of the requirements to be considered when selecting an AC drive and electric motor for use in hazardous environments within chemical, oil and gas. The focus is on using ABB low voltage AC drives alongside an ABB AC motor. With this combination, users can rest assured that by following the advice contained herein, a safe and reliable ATEX approved installation will result. ABB 3AUA REV A EN Products Effects of an AC drive on the motor When controlling motors in potentially explosive atmospheres, it is important to be aware of the effects an AC drive has on the motor. The effect of an AC drive on the operating conditions of a motor changes, compared to Direct On Line (DOL) operation, due to: Higher voltage stress due to steep voltage pulses Common mode voltages and currents Higher motor surface temperature rise due to non-sinusoidal supply For these reasons ATEX directives call for extra attention to be given when an Ex motor is used with an AC drive. Factors affecting selection of Ex motor and AC drive Main sources of ignition risk The main sources of risk affecting AC drives and motors in hazardous environments are: Sparks in the motor windings due to insulation breakdown caused by steep voltage rises and reflected voltages. Sparks in the motor bearings - due to common mode voltages caused by the AC drive. Increase in the motor surface temperature - resulting in reduced cooling capacity or overload of the motor. Reduced cooling capacity is caused by driving the motor outside its specified speed range. Increased surface temperature can occur if the motor is incorrectly dimensioned for use with an AC drive. Protection against ignition from sparks in the motor windings The steep voltage rises in the output waveform of some AC drives can cause stator winding insulation breakdown. These voltage rises can also lead to another phenomenon called reflected voltages, which can increase the motor terminal volts by as much as 2.5 times the nominal voltage. For nominal voltages between 500 V and 600 V, the motor needs either reinforced insulation or the drive requires du/dt filters. Above 600 V, both reinforced insulation and du/dt filters are needed. Please consult the motor manufacturers catalog for more detailed instructions. More information on pages 11 to 12. Total accumulated voltage Original voltage pulse Reflected voltage pulse Figure 1. Refl ected voltages can cause sparks in motor windings. Protection against ignition from sparks in the motor bearings An AC drive can be a source of common mode voltages. Depending on the motor frame size, this source can induce voltages across the frame of a motor, which in turn can give rise to a current through the motor bearings. This can cause premature bearing failure with a risk of sparks, which could cause ignition. For motors with frame size IEC 280 and above, insulated non-drive end bearings are critical to break the potential paths for circulating currents. In addition to insulated bearings, a common mode filter within the AC drive is required for motors with frame size IEC 344 and above. The above measures will reduce the risk of ignition and prolong the bearing life. 4 3AUA REV A EN ABB Products Protection against excess motor surface temperature High motor surface temperatures may be caused by running the motor at reduced speed without adequate cooling. With a shaft mounted cooling fan the reduced speed will reduce the air flow available to cool the motor. For use in hazardous area locations, the motor surface temperature rise must be rigorously tested in accordance with the appropriate standards. The methods for ensuring the correct motor surface temperature depends on the flammable material surrounding the motor. The key goal is to ensure that the surface temperature stays below the allowed limits. For some cases, only testing is allowed; while for others, direct measurement is possible; while some require calculations as a last option, if testing is not practical. Method 1: Use a direct temperature measurement signal from the motor and use this signal to initiate shut down when excess temperature is present. This is only valid for stator-critical motors. How to obtain certification The motor, especially when used with a non-dtc drive, can be protected using direct thermal control. This can be achieved using thermal sensors in the motor windings that control either a certified disconnection circuit or contactor. Method 2: To control and limit the power which is transferred to the motor and thus prevent excess temperature. To achieve adequate cooling of motors driven by AC drives, separate cooling is sometimes used as the fan speed of a self-cooled motor drops with the motor speed. How to obtain certification Option 1: When using an ABB industrial drive, its motor control platform - Direct Torque Control (DTC) - can help reduce the temperature. Using DTC control, along with ABB s dimensioning and selection tool DriveSize, prevents overtemperature. The dimensioning is based on type tested load capacity curves. This also ensures the application is optimized for the load. Option 2: Combined test with motor and drive to ensure that the motor surface temperature does not exceed the limits. Motors with separate cooling Self-cooled motors T/T N (%) Figure 2. Typical motor load capacity curves. Frequency (Hz) ABB 3AUA REV A EN Products ABB drives ABB drives is the generic name used to define the portfolio of AC drives, from 0.18 to 5600 kw, manufactured by ABB. ABB is a world leading brand that is recognized as the global number one supplier of low voltage AC drives, with the widest available range from any manufacturer. ABB drives is a reference for drives users the world over signifing reliability, simplicity, flexibility and ingenuity, throughout the lifecycle of an AC drive. ABB industrial drives, 0.55 to 5600 kw ABB industrial drives are available as complete AC drives and as modules to meet the requirements of the chemical, oil and gas industries. These highly flexible AC drives can be tailored to meet the precise needs of industrial applications and as such specific configuration of the drives can be carried out during ordering. The complete drives and modules cover a wide range of powers and voltages. ABB industrial drives come with a broad selection of inbuilt options. These drives can be easily programmed which makes adaptation to different applications easy. Adaptive programming - like having a PLC (programmable logic controller) inside the drive DTC (Direct Torque Control) - well proven motor control platform All major types of drive topology covered - 6-pulse, 12-pulse, 4-quadrant, low harmonic, air-cooled, water-cooled, etc. Wall-mounted drives from 0.55 to 200 kw, (230 to 690 V) Free-standing drives from 45 to 560 kw, (230 to 690 V) Drive modules from 0.55 to 1900 kw (230 to 690 V) Cabinet-built drives from 45 to 2800 kw, (380 to 690 V) Multidrives from 1.1 to 5600 kw, (400 to 690 V) What is DTC? Widely recognized as a major leap forward in motor control, DTC (Direct Torque Control) is an optimized AC drives control principle where inverter switching directly controls the motor variables i.e. flux and torque. The measured motor current and voltage are used as inputs to an adaptive motor model which produces an exact actual value of flux and torque every 25 microseconds. This is the motor control method used in the ABB industrial drive. 6 3AUA REV A EN ABB Products ABB standard drives, 0.75 to 355 kw ABB standard drives are simple to buy, install, configure and use, saving considerable time. They are widely available through ABB s channel partners, hence the use of the term standard. The drives have common user and process interface with fieldbus, common software tools for sizing, commissioning, maintenance and common spare parts. Assistant control panel providing intuitive use of the drive Patent pending swinging choke for superior harmonic reduction Sensorless vector and scalar control Note: These drives DO NOT feature DTC Wall-mounted drives from 0.75 to 110 kw, (380 to 480 V) (230 V also available) Free-standing drives from 110 to 355 kw, (380 to 480 V) ABB general machinery drives, 0.37 to 22 kw ABB general machinery drives are specifically designed for use in machines. The drives are designed to be the fastest drives in terms of installation, setting parameters and commissioning. The basic products are as user-friendly as possible, yet providing high intelligence. The drives offer diverse functionality to cater for the most demanding needs. IP20 as standard (UL type 1 as option) Advanced functionality with sequence programming Configuration of unpowered drive in 2 sec. ABB 3AUA REV A EN Products ABB hazardous area low voltage motors Flameproof motors, frame size 80 to 400, 0.55 to 630 kw Increased safety motors, frame size 80 to 560, 0.25 to 1000 kw Non-sparking motors, frame size 71 to 560, 0.25 to 2000 kw Ex td/dip motors, frame size 71 to 400, 0.25 to 630 kw (see below) Terminal boxes of ABB low voltage Ex motors are designed for 240 V or higher and thus meet the requirements of AC drive use. ABB Ex td/dip motors With Ex td/dip motors, any explosion transmission of dust is prevented. The following should be considered when using Ex td/dip motors. The ingress of dust into the motor is prevented - IP55 or IP65 for non-conductive dust and IP65 for conductive dust. The maximum surface temperature outside the motor must not exceed the temperature class for which the motor is certified. No sparks must occur outside the motor enclosure. When using an AC drive: Certification can be based on type test results or calculation results - depends on agreement between the manufacturer and certification authority. Certificate for Ex td/dip (in Zone 22 area with non-conductive dust) motors with AC drive can be announced by factory or authorized certification body (third party certification). Certificate can be machine specific or standard type. 8 3AUA REV A EN ABB Products Considerations when using an ABB drive with a non-abb motor This brochure aims to show the merits of using an ABB low voltage AC drive with an ABB motor and the benefits of this ATEX approved combination. However, while ABB drives can be used with motors from other manufacturers it is important to consult the motor manufacturer. In particular, the following considerations need to be discussed: Load capacity of the motor. Protection method - see page 5 for options. Peak voltage. du/dt limitation - needed to combat steep voltage rises in the output waveform. du/dt filters protect motor insulation and reduce bearing currents. Approval (test/calculation). ABB 3AUA REV A EN Products The route to EC Declaration of Conformity for ABB low voltage AC drives and motors Important note: This flowchart only applies to standard ABB motors If the motor voltage is 500 V Up to IEC Check the frame size:...a standard motor is ok ABB drive without DTC Ex na IEC 280 to motor needs...insulated non-drive end bearings Ex p IEC 355 and above... motor needs AC drive needs...insulated non-drive end bearings...common mode fi ltering installed ABB drive with DTC Ex d Ex de Ex td/dip If the motor voltage is 500 to 600 V Motor needs reinforced winding insulation OR AC drive needs du/dt filtering fitted In addition, check the frame size. Up to IEC if a du/dt fi lter is selected for the drive (as above) a standard motor is ok IEC 280 to motor needs...insulated non-drive end bearings IEC 355 and above... motor needs...insulated non-drive end bearings AC drive needs...common mode fi ltering installed If the motor voltage is 600 to 600 V Motor needs reinforced winding insulation AND In addition, check the frame size. AC drive needs du/dt filtering fitted Ex na Up to IEC no additional motor or drive requirements other than those above Ex p IEC 280 to motor needs...insulated non-drive end bearings Ex d Ex de IEC 355 and above... motor needs...insulated non-drive end bearings Ex td/dip AC drive needs...common mode fi ltering installed 10 3AUA REV A EN ABB Products Figure 3. EC Declaration of Conformity for ABB low voltage AC drives and motors Additional testing required to obtain EC Declaration of Conformity Please check motor load capacity curves to ensure correct dimensioning of the motor EC Declaration of Conformity ABB industrial drive, without DTC ABB general machinery drive, ACS350 ABB standard drive, ACS550 ABB industrial drive DriveSize - Using ABB s DriveSize tool, users can select a suitable combination of motor and drive. The tool also shows combinations that have not been tested. Web site - contains all relevant certifi cates for tested drive and motor combinations. EC Declaration of Conformity ABB 3AUA REV A EN Expertise What is a potentially explosive atmosphere? The following constitutes a potentially explosive atmosphere: The frequency with which a potentially explosive atmosphere may exist. The capability of a gas or dust laden atmosphere to ignite. Explosive gases and dust are classified according to the likelihood of their ignition, and other characteristics including: Minimum ignition energy Minimum ignition temperature Layer ignition temperature Because of the addition of dust within ATEX 95, the new directives will include a large number of industrial sites which were not regulated under the previous explosive atmosphere directives. These industrial sites include power plants using coal or organic material, timber industries, the food industry, etc. Atmosphere Zone Definition Gas 0 Explosive atmosphere is present continuously, for long periods or frequently due to Dust 20 malfunctions Gas 1 Explosive atmosphere is likely to occur due to expected malfunctions in normal Dust 21 operation Gas 2 Explosive atmosphere is unlikely to occur or, if occurring, is likely to only be of short Dust 22 duration and not in normal duty Table 2. Categorization of Zones Connection between ATEX 95 and ATEX 137 ATEX 95 and ATEX 137 cover any electrical or mechanical product/ equipment that constitutes a potential source of ignition risk and which requires a special design or installation procedure to prevent an explosion. Safe operation of the product/equipment is the result of cooperation between the manufacturer, the end-user and, if involved, the contractor. However, the responsibility for explosion protection of the product/equipment can never be contracted out to a third party. The manufacturer is responsible for ensuring that the product/equipment is safe when it leaves its factory. The end-user is responsible for ensuring that the product/e
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