Lenze ATEX-compliant gearboxes Gearboxes for use in potentially explosive atmospheres

Lenze ATEX-compliant gearboxes Gearboxes for use in potentially explosive atmospheres

ATEX for drive technology The ATEX directive, which has been in force since July 1, 2003, has been introduced in an attempt to harmonise the various national standards and to provide standardised European guidelines governing the use of equipment in potentially explosive atmospheres. The new guidelines not only provide a critical assessment of the potential risk of explosion from electrical equipment, but for the first time also from mechanical, pneumatic and hydraulic devices and components. This type of equipment was previously classified as non-critical in terms of safety in potentially explosive atmospheres. In addition, the number of zones for potentially explosive dusts has been increased from the previous number of two to three. As a manufacturer, Lenze has analysed its extensive range of modular gearboxes against the background of EU directive 94/9 EC and has implemented various design modifications. As a result, the gearboxes now satisfy the requirements for ATEX category 2. Explosion-protected electric motors can be mounted onto the gearbox via an IEC adapter and a torsionally stiff coupling. As a result, a multitude of combinations can be realised according to customer specifications. Furthermore, it is easy to separate the motor and gearbox for maintenance, resulting in significant cost benefits in terms of spare parts storage. The gearboxes cover a power range up to 45 kw and achieve drive torques of up to 12,000 Nm with finely graduated output speeds. ATEX variants of the familiar Lenze gearbox range are available in the following designs: Helical gearboxes Shaft-mounted helical gearboxes (low-profile gearboxes) Bevel gearboxes Helical bevel gearboxes Helical-worm gearboxes Solid shaft Hollow shaft Hollow shaft with shrink disk Output flange Lenze ATEX-compliant gearboxes Lenze offers a range of products for potentially explosive atmospheres covering all ratio stages of the G-motion range.

Helical geared motors GST 1.6... 400 up to 6000 Nm Shaft-mounted helical geared motors (low-profile geared motors) GFL 3.35... 800 up to 11150 Nm Motor version Integral fan PTC Bevel geared motors GKR 3.5... 75 up to 450 Nm Helical-bevel geared motors GKS 5... 1400 Motor options Separate fan Brake Protection cover Pulse encoder up to 11800 Nm Helical worm geared motors GSS 5...1800 up to 1250 Nm

Gearboxes G-motion range to ATEX category 2 Lenze has undertaken a risk analysis of its extensive range of modular gearboxes and has assessed the ignition danger presented by them. In addition to the temperature analyses of the housing surfaces, the temperature was measured at the rotary shaft seal lip, and depending on the speed and the shaft diameter, this is generally where the highest temperatures are measured during operation. As a matter of course, the ignition dangers resulting from the build-up of electrostatic charge on plastic components were also considered. As a consequence, covers were manufactured from conductive plastic for the shrink disks. Overall, Lenze gearboxes from the G-motion range satisfy the ATEX requirements for temperature class T3. As a general rule, gearboxes and geared motors in industrial manufacturing (equipment group II) are permitted to reach a maximum temperature of 200 C at their hottest point (temperature class T3). With combustible dust the maximum permissible temperature is 190 C. Depending on the application, the limits for the temperature class T4 (135 C max.) can also be achieved using Lenze gearboxes.

ATEX category 2 gearboxes are available from Lenze for use in potentially explosive atmospheres. Lenze offers centralised control cabinet solutions for variable speed motors in conjunction with a frequency inverter in the ATEX categories 2 and 3 for potentially explosive atmospheres. Calculations have shown that for lower-powered motors (up to approx. 7.5 kw) it is more cost effective to use flameproof encapsulated motors in conjunction with a frequency inverter rather than use motors which satisfy the requirements for 'increased safety'. This is because the manufacturer needs to obtain an EC Declaration of Conformity for systems using motors which satisfy the requirements for 'increased safety'. This process is expensive and increases the price of the drive axes, and therefore only makes sense for high-volume orders. In contrast, the use of flameproof encapsulated motors is possible without further official acceptance of the drive train.

Explosion protection primary and secondary measures In order for an explosion to take place, a flammable substance (gas, dust, liquid), a sufficient quantity of oxygen and an ignition source all need to be present. There are currently 13 different known such sources, of which only half are of electrical origin. In addition to sparks, arcing or static charges, hot surfaces, sparks from mechanical origins and ultrasound all play an important role. Explosion protection is not just a matter of flammable gases or evaporated liquids. Today, a significant number of explosions can be traced back to the inadequate protection of dust areas. This is why the ATEX directive is much more concerned with dust explosion protection than previous legislation, and under the ATEX directive the identification and certification of equipment for use in these areas has been substantially expanded. Primary explosion protection is another important aspect of the ATEX directive. Suitable measures are implemented to prevent explosive atmospheres from forming in the first place. These measures include for example the general avoidance of flammable substances and the use of non- or hardly combustible raw materials. Additional measures include the inerting of systems, involving the careful use of inert gases to reduce the explosiveness of flammable mixtures. Other means of preventative explosion protection include the restriction of emissions and the natural and technical ventilation of production areas. Category Zone Degree of Operating conditions/ protection availability 1G 0 Flammable atmospheres are present frequently Very high and for lengthy periods Made to specification not part of the range available 1D 20 from gearbox manufacturers 2G 1 Flammable atmospheres are occasionally present High Lenze drive components available for 2D 21 constant and variable output speeds 3G 2 Flammable atmospheres are likely to occur 3D 22 Normal infrequently and be of short duration Lenze drive components available for constant and variable output speeds

Category 2 Category 3 Gas Zone 1 / 2G Zone 2 / 3G Type of protection EEx d(e) flameproof Type of protection EEx na non-sparking encapsulation with EC Declaration of Conformity with EC type approval test certificate (manufacturer's declaration) Operation of the motor with a frequency When the motor is operated with a frequency inverter is possible without further official inverter an EC Declaration of Conformity acceptance of the overall system. Potential (manufacturer's declaration) is required for ignition source is enclosed in a flameproof the system (comprising frequency inverter housing. Design: motor protected by and motor). Because of the outlay this only flameproof encapsulation, but the connector makes sense for high-volume orders. box is designed for increased safety. Because of the outlay this only makes sense for highvolume orders. Type of protection EEx e increased safety with EC type approval test certificate When the motor is operated with a frequency inverter the system (comprising frequency inverter and motor) needs to be acceptance tested. The outcome of the acceptance test is a new EC type approval test certificate. Because of the large outlay this only makes sense for high-volume orders. The motor can also be used in category 2D and 3D applications. Designed to withstand high temperatures, sparks and arcing. The motor is operated via a starting circuit breaker approved for use in explosive atmospheres. Time to trip determined by the characteristic of the circuit breaker and the current characteristic of the motor. Time to trip must be less than the t E time of the motors (manufacturer's specification). The t E time is the time taken until the critical temperature is reached when the rotor is blocked, according to the temperature class and temperature capacity of the winding. Dust Zone 21 / 2D Zone 22 / 3D Type of protection 2D IP65 T125 C Type of protection 3D IP55/65 T125 C with EC type approval test certificate with EC Declaration of Conformity Explosion protection is ensured by IP type of (manufacturer's declaration). protection and max. surface temperature. Explosion protection is ensured by IP type When the motor is operated with a frequency of protection and max. surface temperature. inverter the system (comprising the frequency When the motor is operated with a frequency inverter and motor) needs to be acceptance inverter a EC Declaration of Conformity tested. The outcome of the acceptance test (manufacturer's declaration) is required for the is a new EC type approval test certificate. system (comprising frequency inverter and Because of the outlay this only makes sense for high-volume orders. motor). Type of protection IP5X for non-conductive dusts; use of Cat. 2 equipment is mandatory for conductive dusts