Hengstler, Germany has launched Acuro® AX65, offering dimensions of 70 mm depth and 59 mm diameter – typically half the size of conventional explosion-proof encoders. The new will prove extremely valuable to system designers seeking space-saving solutions. Furthermore, the fact that the device can be replaced separately from the cable, the presence of fewer hood screws, and the potential for ring network configuration (less wiring), makes the AX65 an attractive proposition for customers looking to lower their total cost of ownership (TCO).

Among numerous attributes, international explosion-proof certification (both ATEX and IECEx for mining, gas, dust) makes the AX65 ideal for global markets that include oil and gas platforms, mines and chemical plants to list but a few. Moreover, the design team at Hengstler has also ensured the AX65 is equally adept in environments subject to constant salt water exposure (thanks to the use of a marine-grade stainless steel housing), while shock resistance of 2000 m/s² and axial/radial shaft load capability of 300 N brings into a range a whole host of applications such as enamelling production line equipment, bottling machines, mixers and silo works, for example.

Despite its size, there is almost no compromise on performance with the AX65. The unit has been subjected to extensive trials at selected customer sites, particularly those suffering previous encoder failures due to a lack of robustness. Typical customer test applications included providing accurate and reliable position feedback in cranes, winches and other types of materials handling equipment deployed on both offshore and onshore oil drilling equipment. Importantly, the encoder is able to function in ambient temperatures down to -40°C.

No issues of insufficient robustness were reported with the AX65 encoder over the course of the three-year trials. As the decoder has no disc (scanning takes place magnetically), the AX65 is particularly resistant to shock (200 G) and vibration (30 G). The use of magnetic technology for both the single-turn scan and the encoder’s new electronic multi-turn, makes the AX65 extremely reliable in harsh operation environments.

The new multi-turn is completely self-sufficient (no battery) and is devoid of contact parts and gears to ensure zero wear and long operating life. Indeed, low TCO is a particular feature of the AX65. For instance, not only can the encoder be installed quickly and easily due to its flexible, quick-connect terminal system, but in the event of servicing, the entire encoder can be replaced separately from the cable. This represents a significant advantage since many platforms use cables of 40m in length or more. Such cables are heavy and cumbersome, and must be laid in ducts. Replacing both the cable and the encoder can therefore be extremely challenging and costly if they cannot be exchanged individually.

Another ease-of-maintenance design innovation is the use of just two screws for the terminal box of this IP66/IP67 rated device (image 2). Hengstler is aware than many comparable encoders use six or even eight screws, while insufficient corrosion protection makes such units very difficult to uninstall. Instead, special agglutinated screws are deployed on the AX65 to protect against dust, water and corrosion. Further value-added design innovations include a shaft load rating that reduces the need for load modules, and a choice of SSI or CANopen interface, which can save wiring costs by allowing a ring network configuration.

Ultimately, no matter how demanding or challenging the application, the compact and cost effective AX65 brings a guarantee of safety and reliability that represents a step-change in the selection, deployment and servicing of explosion-proof encoders.

Thomas Kuner, Product Manager, Hengtsler GmbH. Email: thomas.kuner@hengstler.com