More than half a century ago, Baumer Hübner developed this type of particularly reliable and robust rotary encoders. Since then they have been used in all situations where the going is tough and where failure is not an option. What distinguishes a HeavyDuty rotary encoder exactly and what options do they offer users?

The sophisticated HeavyDuty impermeability concept from Baumer conforms to protection classes IP 66 and IP 67 within a broad temperature range of up to +95 degrees Celsius. Thanks to an ingenious combination of labyrinth and shaft seals, Baumer HeavyDuty rotary encoders are permanently optimally protected against all types of solids, moisture, and contamination by adherence.

Dockside cranes that unload thousands of tons of shipped goods daily. Conveyor systems that carry thousands of tons of mined ore from mining plants across many kilometers. Elevators that carry thousands of people daily. Automated production lines on which automobiles in various assembly stages are transported. Lifting bridges with a total weight of 1000s of tons that can carry several trains at once and that are lifted many times per day to allow ships to pass. These and many other application scenarios constitute the world of HeavyDuty rotary encoders – anytime difficult tasks must be reliably carried out under difficult conditions and over the long term.

The term has been linked to Hübner Berlin since the 1950s, when the company established the supreme rotary encoder class. Since that time, Hübner Berlin, which today belongs to sensor specialist Baumer, has continuously improved its products and is still considered the expert provider of HeavyDuty rotary encoders. But what do we mean when we talk about HeavyDuty products? After all, the term is not legally protected or regulated by a standard. “Heavy duty” as such simply means hard-wearing. A possible reason why some people think that HeavyDuty rotary encoders are simply encoders with thick housing walls and rust protection. In reality, the term denotes much much more.

What makes a rotary encoder “HeavyDuty”?

To Baumer Hübner, “HeavyDuty” is an all-encompassing performance promise. First of all, this means that such a rotary encoder never lets its user down, even under the most difficult conditions. And secondly that these heavyweights work as precisely as “small” rotary encoders for an extended period of time. HeavyDuty rotary encoders from Baumer Hübner accomplish this through four characteristics:

Precision: A rotary encoder must deliver reliable signals to allow users to precisely control and regulate drives and generators. Plant control systems utilize these signals for speed monitoring of drives or for position feedback of machine parts. To controllers, this information is the only way to get informed and intervene, for example, if a drive exceeds or falls below a defined speed limit. Since the machines and systems are usually very big – dock cranes, bucket-wheel excavators, rolling mills, garbage shredders – they could give the above-mentioned impression that precision does not matter much. That is a mistake. Particularly because heavy loads are moved with great force, small measuring errors could have extensive consequences, for example, when setting down a container weighing several tons.

Mechanical robustness: a HeavyDuty rotary encoder must be so resilient that it can withstand hard shocks, vibration, and forces on the rotary encoder shaft for many years. Exchanging rotary encoders is expensive, not because of pricing but because of installation in places difficult to access and the system being down for the time of exchange. HeavyDuty rotary encoders are distinguished by several characteristics: Double-sided bearing setup with generously dimensioned, largely spaced bearings at both shaft ends to compensate axial and radial load, robust and thick-walled housings, and durable protection of the inside components against shocks and vibration.

Tightness: HeavyDuty rotary encoders are usually deployed in dusty, soiled, and damp environments. For this reason, the HeavyDuty encoder housing must be well sealed, especially at critical, neuralgic points – the shaft and electrical connections. Further, in terms of potential contact to chemicals or salt water, a good corrosion protection through appropriate housing materials and coatings is mandatory.

Electrical robustness: HeavyDuty rotary encoders must be immune against electromagnetic fields. These are generated by live, unshielded cables routed nearby, which is a quite common situation in many applications. Without adequate shielding, the electronics in the rotary encoder might be destroyed or provide erroneous measuring signals. Another point are shaft currents caused by potential differences. They may burn the bearing lubrication, which results in bearing destruction. For all these reasons, the inside electronics of HeavyDuty rotary encoders must be electrically isolated from the ambiance of operation.

Whether absolute or incremental – above the standard

As described above, there are diverse application areas for HeavyDuty rotary encoders. Therefore, the HeavyDuty portfolio of Baumer Hübner is just as diverse with many variations of incremental or absolute rotary encoders. The HOG 10 / POG 10 is the reference device among incremental rotary encoders. The rotary encoder HOG10 provides even more features only offered by Baumer that can enormously increase the fitting accuracy, as shown by the following two examples:

HeavyDuty rotary encoders are usually deployed in harsh environments with exposure to dust, moisture, and chemicals and therefore require powerful protective seals. But not all seals are equal. This is why HOG 10 is available with several sealing concepts for optimum protection in oily, damp, or dusty environments, for use in tropical and offshore climates, in cement works or other demanding environments. There are, for example, reliable and absolutely wear-free seals that endure impacts by coarse and fine-grained solids and whose sealing components function with absolute wear and tear durability. In addition, sealing free from friction prevents any performance loss. Such a sealing concept is most efficient and less energy-consuming at high speed.

Since HeavyDuty rotary encoders are generally deployed in giant installations, signal transmission must often cover a distance of 100 meters or more. For this reason Baumer attaches great importance to excellent signal quality and high-power outputs using short-circuit proof power transistors. There are even product variants that are capable of a distance up to 550 meters. Where this is not sufficient, fiber optic cables ensure noise-immune signal transmission over a distance of 1.5 kilometers.

Similarly, absolute rotary encoders such as the HMG 10 / PMG 10 also have special features beyond those of standard encoders: for example, providing precise position outputs via PROFINET. Frequently, incremental signals are also required for speed feedback in absolute rotary encoders, which is why absolute HeavyDuty encoders deliver speed signals in addition to the absolute position, for example as HTL or TTL, via serial digital interfaces such as SSI or fieldbus. Some product variants even integrate a speed switch for limit speed information via switching output.

Flexible solutions for every application

There are various mounting options, whether as hollow shaft designs (through or non-through), cone shaft, or solid shaft with optional EURO flange B10 connection. If required, HeavyDuty rotary encoders, speed switches, and tacho generators can be combined in one single robust, space-saving unit to provide varied types of output signals measured at a single drive shaft all at once. Large encoders such as HOG 16 / 22 /28 from Baumer are used for maximum speed limit monitoring of large drive shafts under the most difficult conditions, such as in coal dust, corrosive air, or in the burning heat of steel mills.

Due to the many available options, interested buyers should best check first together with our experts which HeavyDuty rotary encoder is appropriate for the intended application. No matter what product you opt for in the end – above-average precision and durability are always part of the package of HeavyDuty rotary encoders from Baumer Hübner.

Source: Mepax

The post Baumer Hübner explains HeavyDuty high-precision heavyweight rotary encoders appeared first on North America FarmQuip Magazine.

Every day and for many years, the cable railway traveling in the Tyrolean Alps to the top of Zugspitze has been carrying hundreds of people to an altitude of 2,964 metres. At a speed of 10 metres per second, the trip takes about seven and a half minutes, powered by two electric motors of 500 kW. In the driver’s cab, control of the current motor status – slow, idle, forward, reverse, accelerate, high-speed and brake – requires a high level of accuracy and reliability by the speed control system. After all, passenger comfort and safety are first.

However, the components in mountain railways are exposed to harsh conditions: wind, rain and snow shape the ambience, temperatures range from double-digit minus degrees in winter to high plus degrees in summer. A perfect application example for the HeavyDuty tacho generators from Baumer Hübner, here analog tachor generator TDP 0.2 LT which is a particularly robust and precise speed sensor variant. What exactly does “HeavyDuty” mean?

HeavyDuty as encompassing performance promise

“HeavyDuty means “heavy-duty”. To Baumer Hübner, however, this is much more than thick-walled housings and corrosion protection. HeavyDuty is the encompassing promise of never letting users down thanks to reliable performance for many years. A prerequisite particularly in mountain railway applications. To ensure this, some specific criteria must be met:

Mechanical robustness of course is key. Tacho generators in mountain railway drives must withstand shocks, vibration and other impacts the rotating shaft is exposed to for many years, without losing any of their functionalities. After all, product exchange is expensive, not because of tacho pricing but because of installation in places difficult to access and system downtime during exchange. Robust housings with solid walls are a good start, so TDP 0.2 LT comes in a die-cast aluminium housing and with stainless steel shaft. But also the interior must be protected against shocks and vibration. TDP 0.2 LT with bearings at both shaft ends is capable of enduring high radial and axial shaft load.

HeavyDuty tacho generators must withstand dust, dirt and moisture which requires a sufficient level of tightness. For this reason, the HeavyDuty housing is well sealed, especially at critical, neuralgic points – shaft and electrical connections. In addition, appropriate materials and coatings protect against corrosion by salt water or chemicals.

Tacho generators do not integrate electronics and therefore are extremely durable against harmful impacts by electromagnetic fields. So, nothing stands in the way for routing live, unshielded cables nearby. Furthermore, shaft currents induced by voltage differences might burn the bearing lubrication which results into bearing destruction. The electrically insulated interior of HeavyDuty tacho generators is therefore well protected against such harmful influences.

Last but not least, precision is another valuable virtue of these HeavyDuty heavy weights. Tacho generators must deliver reliable signals at all times to ensure precise drive control and regulation. Based on the speed information, the controller can identify any drive speed deviation and will intervene. HeavyDuty tacho generators in heavy vehicles such as mountain railways must be as precise as smaller speed sensors. It is not without reason that TDP 0.2 LT is field-tested and extremely reliable. It delivers a 60V output signal already at 1000 rpm; at the maximum operating speed of 10,000 rpm the controller is even provided with up to 600V.

High-precision tachometer voltage throughout the entire speed range

The conventional combination of copper commutator and graphite brushes in tacho generators has long been outdated. The copper oxide layers on the commutator cause irregular transition resistance and thus high ripple in tachometer voltage, so low speed would not be accurately detected. However, graphite with good sliding properties ensures a long brush service life. The combination of copper commutator and silver graphite brushes is much more appropriate for low speed detection, since precious metal brushes apply a highly conductive “patina” to the commutator. However, this solution is sensitive to adverse ambient conditions such as oil, grease or air containing sulphur and salt. Under such conditions no patina would build up and the said good transmission properties would be lost over the entire speed range. In addition, there is increased wear because the metal-containing brushes run directly on the copper layer.

LongLife® is what Baumer Hübner calls their tachometer technology patented in 1987 which combines the positive of above procedures and eliminates the drawbacks. In a special process and depending on the tacho variant, Baumer Hübner embeds one or two massive silver tracks into the commutator surface. The track can be very fine thanks to relatively minor tacho currents. TDP 0.2 LT features even two silver tracks. This ensures permanent low contact resistance even under difficult conditions. And it allows for a 60 mV/min-1 voltage constant of TDP 0.2 LT resulting in a wide detectable speed range from ≤ 0.08 to 10,000 min-1, with both mechanically and electrically limited maximum speed. TDP 0.2 LT therefore provides a dynamic range of 1 : 125,000. The brushes especially modified by Baumer Hübner together, with the LongLife commutator ensure maintenance-free service life that even will exceed that of the ball bearings.

LongLife® even for ski lifts

Ski lifts carrying millions of skiers to mountain peaks every year have likewise tough requirements on drive control. Here too, to ensure passenger safety manufacturers rely on tacho generators that have proven themselves in many applications. They ensure reliable equipment functionality even during severe frost, snowfall and icy winds. Today, speed-controlled drives are also common in ski lifts for smooth starts and variable travel speed. For decades, lift manufacturers have been deploying analog tacho generators by Baumer Hübner such as GMP 1.0. The tacho generator is directly connected to the slowly rotating cable wheel via step-up converter and chain wheel drive. This way, dead speed in the motor gearbox is isolated from the control loop and generates sufficient speed signals even under harsh ambient conditions. The GMP 1.0 also features two silver tracks for permanent low contact resistance and thus a widely detectable speed range with good transmission quality of measured values. The robust design and standard temperature compensation make the tacho generator ideal for use in the harsh conditions of snow-covered mountains.

More than half a century of experience in HeavyDuty tacho generators and encoders has evolved the comprehensive Baumer Hübner portfolio of reliable, precise and durable product variants – from small to large designs. They support all relevant analog and digital interfaces and excel with the capabilities required to withstand even adverse ambient conditions. Application examples like mountain railways and ski lifts clearly prove that for users with high requirements the HeavyDuty Original is the right choice in this encoder class.

Source: Mepax

The post Baumer Hübner aims at precision and reliability appeared first on North America FarmQuip Magazine.