The removal and disposal of spent fuel rods from a nuclear reactor is an extremely precise and controlled process. Used fuel rods are placed at the bottom of a spent fuel pond to begin a process of cooling that will last for years. The highly specialised overhead gantry crane used to transport and position the fuel rods must offer complete reliability. For a recently commissioned crane in the Czech Republic, the OEM chose to specify the NFF Series of compact electromagnetic brakes from Stromag, a premier brand of Altra Industrial Motion Corporation.
Every 12 to 24 months, up to one third of the total fuel load of a nuclear reactor is removed from the core. The spent fuel rods, fresh from the core, will be generating immense amounts of heat and radiation that must be controlled and contained locally, prior to being moved into dry casks for final disposal. The spent fuel pond is typically at least 12 metres deep, with temperatures carefully managed to remain below 50 °C. The pools contain boric acid for its neutron-absorbing capability, which reduces the ionising radiation emanating from the rods and helps to ensure subcriticality.
When one of Europe’s leading manufacturers of nuclear reactors and related equipment was asked to design a new overhead gantry crane to move spent fuel rods into the pond, it knew that only the most reliable components could be specified. The gantry is used irregularly, often with many days between each operation. As such, critical components such as the motors, winch and brakes must be suited to periods of inactivity without servicing or maintenance. The holding brakes on the winch and the trolley drives are particularly important, as they would only be used in the event of a power failure, at which point they would be required to perform holding duties.
Kay Wendelberger, Customer Care Engineer for Stromag, comments: “Having worked with the manufacturer previously, we were aware of the application demands of such an environment. In addition to requiring a braking system that would operate reliably despite infrequent use, the manufacturer was looking for a compact solution that would provide protection against dust and humidity. The spring-loaded electromagnetic NFF Series provided all the required functionality, including IP66 protection and specialised surface treatment for long term reliability in even the harshest environments.”
The NFF Series of double-face, spring-applied brakes were designed to provide reliable braking for applications that are exposed to harsh environments. The double-face design facilitates high braking forces with a compact footprint, which is ideal for crane applications where space is limited. All of the steel components on the brake feature special nitrocarburated and postoxidated surfaces to provide protection against humidity, dust and corrosive materials.
For this particular application, the brakes were required to perform holding duties in the event of a power failure affecting the gantry crane. The crane’s twin trolley drives required multiple NFF 4 brakes with a torque rating of 44 Nm. A single NFF 400 brake was fitted to the winch drive with a torque rating of 4,400 Nm. The spring-applied, electromagnetic brakes are held open while power is supplied to the brake, allowing the crane’s drive system and winch to manage speed and positioning. In the event of a power failure, the brake closes automatically, holding the crane in position while any necessary maintenance or repair work is carried out.
Kay concludes: “The NFF Series is designed to be directly mounted onto the motor’s shaft with no brake disassembly required. This ensures fast installation and minimises the footprint of the application. Our engineers worked closely with the OEM to ensure the models we supplied were best suited to the application and that installation and commissioning occurred without any problems. The gantry crane is now in operation at the nuclear plant and we are working with the manufacturer on other similar projects.”
ERX Electromagnetic Brakes combines for automation applications
Warner Electric, a brand of Altra Industrial Motion Corp., has released a new range of pre-assembled electromagnetic brakes that offer superior performance for stopping and parking applications. The brakes can be specified in standard, high-torque or high-speed configurations and with a selection of accessories included. Thanks to its modular design and efficient stock holding, Warner Electric is able to offer thousands of variations with a very short lead time.
Complementing the smart design of the ERX range, Warner Electric has developed an easy-to-use configurator that allows engineers and purchasers to reliably order the part they want. Having first chosen between five brake sizes and three friction materials, hub bore diameter instructions are given followed by yes/no choices for the five options available. Once a code is generated and the order is placed, each component part is taken from stock and the complete brake is assembled and shipped.
As standard, the brakes provide braking torque from 5 up to 60 Nm. The high-torque option increases braking torque to 75 Nm and the high-speed version facilitates between 3,500 rpm (60 Nm) to 7,000 rpm (5 Nm).
All of the brakes are supplied with ‘non-stick’ friction material that has been developed by Warner Electric to stop brakes from seizing whilst closed. For automated processes where brakes are only applied occasionally, yet must be relied upon at a moment’s notice, this is of particular importance.
The five optional features allow customers to specify a hand lever for manual release; an IP54 protection kit; a double brake with two magnets and two friction discs for full redundancy; a ‘silent option’ – better than 55dB(A); and the Warner Electric Sensor (WES) – a contactless solution to monitor the position of the armature and provide feedback on wear measurements.
The WES outperforms traditional electromechanical designs thanks to a very low hysteresis: less than 0.05 mm between the full range of operating temperatures (-40 °C up to 105 °C). Both NPN and NO/NC outputs are available – the former with an integrated pull-up resistor to simplify integration into most PLC-based installations and the latter providing backward compatibility with almost all dry contact switches on the market. An optional analogue ratiometric output is also available, which offers real time wear detection that measures the brake air gap down to 0.15 mm.
The ERX range brings a level of versatility to designers and engineers that is unprecedented for electromagnetic brakes of this type – this will only improve as the maximum braking torque will increase to 400 Nm soon. As part of Altra, Warner Electric is able to support the product performance with a global supply and service network – ensuring that the ERX is a premium solution for Smart Factory applications.
New standards for brake performance, reliability, flexibility and low noise levels
Warner Electric, a brand of Altra Industrial Motion, has developed a new family of brakes for stage and theatre applications, combining increased performance and reliability with very low noise levels, and a host of features specially requested by users in this demanding sector.
The compact designs provide braking torques from 5Nm to 4,600Nm, and feature a newly designed friction material developed especially to meet the requirements of stage and theatre applications. Warner Electric’s new Fenix family of brakes has been developed to provide the most reliable dampening system on the market. The range comprises three models: Fenix 08, with a single magnet and a single friction disc; the Fenix 10, with a single magnet and two friction discs, offering double the torque in the same package size; and the Fenix 09, featuring two magnets and two friction discs to provide full redundancy. The friction disc material is a new development from Warner Electric, not only to provide increased braking torque but also to address a specific issue within the stage and theatre industry – that of condensation. When the brakes are packed away after a show, having spent many hours high up in theatres in close proximity to hot stage lights, the rapid cooling from the high temperatures can cause condensation to form. In standard brake designs, this can cause the friction discs to swell and stick. This creates problems at the next time of use, as well as damaging the friction lining. The new Warner Electric material overcomes this problem, while also eliminating associated risks of corrosion, significantly increasing the life of the brake in this environmentally challenging application. The brakes also benefit from a new noise dampening system, reducing noise to better than 45db(A) straight out of the box – a feature requested by the industry. And Warner Electric guarantees noise levels of better than 50db(A) throughout the lifespan of the brakes, which is rated at 17 million cycles. As further innovation, all of the brakes include Warner Electric’s WES sensing technology as standard – a contactless solution to monitor the position of the armature and provide feedback on wear measurement. With very low hysteresis compared with conventional micro switches, and the elimination of drift of the switch point with temperature, use of the WES means that sensing distance is no longer a constraint, enabling the brake air gap to be reduced to as little as 0.15mm, giving increased braking torque. All of the brakes in the Fenix range also feature a dust cover and connections for an encoder as standard, and options for hand release. Furthermore, they are available in either high torque or high speed configurations. All of this enables each brake to be tailored to the precise requirements of individual applications. All of the brakes in the new Fenix family are certified to standards relevant to stage and theatre applications, including BGV-C1, DIN 56950-1, EN81-20/50 and DGUV 17.
Stromag high performance brake
New modular, IP67 rated brake offers optimum performance and longevity for marine, offshore and other demanding applications.
Stromag, part of Altra Industrial Motion Corp, has launched a new, modular range of brakes designed for applications in challenging environments. The HPB (High Performance Brake) is an electromagnetically operated design that activates automatically in the event of a power failure to hold or stop loads. The new range is designed for working, holding and sudden stop applications, and is intended to deliver superior performance over a long working life.
The HPB is available in two-face or four-face configurations offering a brake torque range of 80 to 5,000Nm. Stromag has combined the latest design and manufacturing technologies with its 86 years of experience in mechanical systems to create a design that offers maximum performance in a small space envelope. The company has paid particular attention to the thermal characteristics of the brake, achieving superior heat dissipation for reliable dynamic performance.
The internal components of the HPB are all designed to resist corrosion and offer enhanced durability where exposure to salt water or other contaminants is likely. The new brake range is available in IP67 rated configurations, allowing it to operate where flooding or immersion in seawater is a possibility.
Considerable attention has also been paid to the electrical design of the brake, with rectifiers and quick switching units that optimise the switching characteristics and offer easiest installation. To aid integration in customer applications, it is available with a wide range of options, including tachometer mounting, an anti-condensation heater and microswitches to monitor switching operations and wear.
Applications for the HPB brake range include cranes, winches and hoists in harbour, marine or offshore applications. The new brake is also suitable for use in industrial environments where long-term reliability and resistance to harsh environments is a priority.
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