kubler articles

Platform for Robust Sensors

Kubler 3/1/2018

Platform for Robust SensorsThe encoders of the modular Sendix Plus range are designed for inhospitable conditions. These sensors are for example suitable for fire trucks and wind turbines. Largely dimensioned ball bearings improve the resistance to shocks and vibrations. 
 
Encoders have established themselves for position feedback, speed and rotary speed measuring in industries with particularly hostile environmental conditions. But, if we set the burning temperatures, strong shocks and vibrations with dust, corrosive chemicals or thick mud the applications have to cope with in relation to the electromechanical equipment, there seems to be a basic discrepancy: the opposition between accurate measurement and a particularly robust design of the surrounding parts.

More precisely: on the one hand there are precision mechanical encoders with filigree construction, shafts and bearings, and on the other hand heavy duty machines, which do not stop, even in front of steel or granite. Incremental encoders have firmly established themselves in the sector of mobile automation, as well as in many other sectors with particularly tough environmental conditions. The demands placed on the sensors have been growing enormously in recent years. Constantly increasing functionalities, higher efficiency and quality requirements for the work processes require an efficient and above all scalable automation system. As varied as the applications are also the requirements of the users. 
 
Find quickly a suitable sensor

The perfect encoder for every case cannot exist. But there can exist a suitable modular encoders system. The Kubler Company offers for example a modular products range with different variants for every application case, even in extreme conditions, which can be implemented cost-effectively. To that purpose, the manufacturer relies on a scalable, modular products range that can be extended according to the needs and offers a transparent and suitable solution. The modular products range Sendix Plus is based on the Sendix encoders range, which is used, thanks to its protected, fully interlocked bearing structure, in many sectors. This components group combines robustness and modularity.

The bearing structure in Safety-Lock design is available both for the solid and for the hollow shaft variants; it operates in a reliable and, above all, fail-safe way, even under extreme conditions. The encoders feature particularly large ball bearings. This bearing structure allows the encoders to withstand shocks, vibrations and installation errors. They are especially suitable for demanding outdoor applications of any kind. Goal of the modular range: if a user is looking for an encoder, the manufacturer determines quickly and with a view to costs the most suitable variant for his specific application. 
 
Airport fire trucks

Fire trucks used in airports or for civil protection, sometimes also in crisis areas, are an example of an application area of these sensors. They belong to the most efficient of their kind. They can contain tens of thousands of liters of water or extinguishing foam and they drive to the fire at a speed reaching 140 kilometers per hour. A fire truck saves lives. It must be designed to meet without restriction all the various intervention requirements.

For mechanics, airport fire trucks belong to the harshest application ranges. Water and extinguishing foam penetrating in the tiniest cracks and extreme temperatures, together with vibrations and shocks, pose ultimate demands to the employed technology - in particular sensible sensor technology such as encoders. In new airport fire trucks, the encoder bearings must be particularly vibration-resistant. The sealing lips must ensure secure protection against humidity, but also against chemicals, the IP67 or IP69k protection level must be guaranteed for a long service life. Reliability, rapidity and safety, these are the crucial characteristics in the hectic of an intervention. The breakdown of a component as small as an encoder during an emergency must be excluded with certainty. 
 
Magnetic or optical encoder

The magnetic multiturn encoders, as well as the 5868 series with nanocoating and Canopen interface, M3668 are suitable for use in fire trucks. The magnetic measuring principle of the M3668 ensures insensitivity to temperature fluctuations or humidity, which push even optical encoders equipped with special protective housings to their limits. Tight installation spaces are no problem either for this compact sensor. One of the adaptation possibilities offered by this magnetic encoder is the encapsulating of the scanning head, ensuring particular protection of the integrated electronics.

In addition, the shaft seal can be protected mechanically, reaching protection levels IP66, IP67 and IP69k. Extra large bearings ensure high bearing load capacity, reaching the strength level of the 58 mm-size encoders. The 5868 encoder offers higher resolutions and signal accuracy; its nanocoating allows successful and safe operation in any condition. The special housing coating compensates its higher sensitivity to environmental influences. If small position changes must be detected, it is thus possible to opt for the 5868 encoder. Both magnetic and optical encoders can suit for a fire truck, depending on the application. Extra large bearings ensure for both types the same high bearing load capacity. 
 
Wind turbines are threatened by corrosion also inside

Besides industries such as steel, cranes or solar power, the wind industry belongs to the central fields of application of the Kubler Plus encoder solutions. Using ever longer rotor blades, the manufacturers are taking the electricity yield of their offshore wind turbines to new dimensions.

Newcomers in the offshore wind energy are looking for further new alternatives to make offshore wind farms both more efficient and more cost-effective. A British Company is experimenting with rotors that rotate parallel to the waves and are only half as high above the sea. This saves money and time for material, erection and maintenance. A Dutch Company is researching into two-bladed wind turbines. 
 
The future of wind power

The future of wind power, especially offshore, has just begun, but the learning curve from offshore plants since 1990 is already showing significant results. Basically, the whole of the wind turbine is threatened by corrosion. But the typical corrosion protection methods of the maritime technology cannot be simply transferred to the wind turbines, as the unmanned operation makes regular maintenance, as it is usual for example on ships, impossible.

Other than it could be expected, the inside area of the tower is threatened by corrosion too, although to a much lesser extent than the nacelle. In order to keep the rotor oriented in the wind, electrical motors rotate the whole nacelle with respect to the tower. If the large tower surfaces then come into contact with the hot air from the nacelle, this results in a notable condensation effect. Humid cold air accumulates in the foot of the tower, where some of the sensors are located. 
 
Corrosion-resistant in five variants

The platform concept for wind turbines includes corrosionresistant encoders in five different variants. These reach from C1/C2 for areas with low or temporary condensation up to C5 for areas with almost constant condensation combined with heavy contamination. The Sendix Plus encoders entirely cover these ranges with variants and special surfaces, materials and processing methods: from Safety-Lock-Standard, through nanocoated "C" versions, V2A stainless steel or seawater-resistant aluminum encoders, up to the V4A seawater-proof stainless steel version.

All possible uses in a wind turbine, from the rotor hub up to the external tower area, are thus covered. This contributes to the reduction of plant downtime and increases availability. And, if the manufacturers can speed up the construction and structure clearly the components range, they will be able to reduce production costs and improve permanent operation.