The news of TWK-ELEKTRONIK GmbH

TWK takes the next step in the direction of 'safety in sensor technology' and introduces the new sensor model TxSN with magnetic sensor system in the series of functionally safe sensors with the established interface standard CANopen Safety (EN 50325-5). This model includes the multiturn encoder TRSN and its small singleturn brother TBSN. It will meet SIL3 level according to EN ISO 61508 and will be certified accordingly and is also ASIL-D compliant according to ISO 26262.

For some applications, the SIL2/PLd safety level is not sufficient. For example, autonomous vehicles, so-called AGVs (Automated Guided Vehicles), which move independently and computer-controlled in public areas. Since the safety requirements are particularly high here - high personal injury and property damage can occur if the vehicle functions incorrectly - a high safety level is required for the technology used. The vehicles must be equipped with SIL3 components, sometimes on the wheels, to detect steering angle and speed. Remote-controlled vehicles that are moved without a driver present should also be mentioned. They are steered remotely from a workstation. With his seat equipped with monitors, pedals and steering wheel, the operator can remotely steer a vehicle equipped with cameras and remote technology to the desired destination. And back again, of course. Fast internet according to the 5G standard is provided for transmission to the vehicle.
TWK offers SIL3 encoders for the control elements of the remote steering station to record the important control commands. The first devices of the TxSN model will be delivered at the end of 2022. The fully redundant design and advanced diagnostic and watchdog functions ensure SIL3 capability. In addition, extensive test procedures for hardware and firmware during the design phase and later for each device to be delivered in production are prerequisites for certification according to IEC 61508 with level SIL3 and ASIL-D conformity according to ISO 26262. Each encoder then outputs the position value, which is recorded twice, checked for plausibility and processed in separate microcontrollers, via the SIL3-capable bus system and the CANopen safety protocol. Normal and bit-inverted. The usual safety check then takes place in the safety control, whether both values arrive within a time window and whether they are identical - except for the inversion. If this is not the case, an alarm is triggered and the vehicle is stopped.
For this model, as well as for the already established SIL2 / PLd models, some features for further applications are planned, which facilitate the design of the customer application. For example, a wide range of robust enclosures is available: seawater-resistant aluminium as standard, various stainless steels - including food-grade, magnetically shielding stainless steel for applications with strong magnetic fields, or special enclosures for versions for explosion protection according to ATEX Zone 1 and 21. The most compact version is the one with a housing diameter of only 42 mm.
Other features of the TxSN: position resolutions up to 16 bits, parameterisable gate time for speed measurement, speeds up to 10,000 rpm and many flange and shaft forms. Protection classes up to IP69K are possible as well as a shaft load capacity up to 250 N axial and radial. The electrical connection is realised via M12 plug or cable.

Further information can be found at: www.twk.de

For decades, TWK has been an innovative and reliable partner to its customers in the wind industry. Since then, TWK has brought innovative products to the market that are precisely tailored to the requirements of the industry. Vibration and rotor hub sensors are joined by electronic cam switches that detect even small rotational movements without backlash. In this case, we have further developed the NOCE with SSI interface and released the PLd variant in the compact 79 series design. The SSI interface itself is not certified, but the built-in safety switching contacts and thus the complete sensor system and signal processing are. The switching contacts consist of positively driven relays with a control contact and an additional standard relay connected in series. This virtually eliminates the probability of a contact not opening in the event of danger. It can be implemented in a safety chain in which various safety components are integrated, in order to bring the application into the safe state in the event of danger. Numerous internal monitoring functions ensure that the NOCE opens all contacts in the event of a fault, thus also ensuring the safe state.
A typical application is the azimuth adjustment of the nacelle of wind turbines. When the wind direction changes, the nacelle is aligned accordingly so that the rotor is always exactly in the wind. In unfavourable cases, the wind may turn in such a way that the nacelle is always readjusted in one direction. To prevent the energy cables in the mast from being torn off by twisting, the turbine must be stopped after approx. 2.5 revolutions and set back to "centre". This safety task is performed by TWK's electronic cam switches.
The NOCE is equipped with a total of four galvanically isolated switching contacts: two safety switching contacts, as described above, and two normal ones equipped with standard relays with a long service life. The switching points can be set with teach-in pins in the connector. The same applies to the preset and code direction of the SSI signal. The teach-in procedure is designed in such a way that accidental changes are excluded and thus the safety criteria are fulfilled. The robust unit made of aluminium or stainless steel with IP67 protection and high EMC resistance meets the required safety standards in every respect. Various flange and shaft versions and also the interfaces IO-Link and CANopen safety are possible. A resolution of the position signal of up to 16 bits is also possible. An additional UL® certificate will be available shortly.

It follows the PROFIsafe TRT78/S3 encoder as another SIL2/PLd representative that also meets the strict requirements for explosion protection according to ATEX Directive 2014/34/EU with zones 1 (gas) and 21 (dust). The robust aluminium or stainless steel housing with cable connection is flameproof (Ex d), i.e. the housing withstands the explosion pressure of internal components that could trigger an ignition. Transmission to the outside is prevented so that explosive gases or vapours in the environment are not ignited. In addition, the enclosure is securely sealed against the ingress of dust (Ex t) and the surface temperature does not exceed 100 °C (T5). The design 78 units thus comply with ATEX Group II, Cat. 2G (gas) with explosion group IIC and Cat. 2D (dust) with explosion group IIIC. The certification complies with the applicable standards of ATEX, IECEx, North America and EAC-Ex. Of course with SIL2/PLd certificate.
The encoder with redundant magnetic position detection and EtherCAT-FSoE protocol according to ETG.5100 version 1.2.0 offers all EtherCAT write/read services and the following features:
Complex slave with CANopen over EtherCAT (CoE),
Fieldbus Memory Management Unit (FMMU) and
Firmware update via EtherCAT (FoE).
Its resolution is up to 65,536 steps / 360° (16 bit) with a measuring range of 4096 revolutions. In addition to the position, the shaft's rotational speed can also be precisely recorded and read out. Different flange and shaft versions as well as the removable connection bonnet allow easy integration of the TRK78 into the application.
The areas of application for this type of sensor are expanding from year to year because, on the one hand, the requirements for the protection of persons and property are increasing and, on the other hand, the characteristics of increasingly automated production plants and their environment require increased safety in the sense of functional safety and explosion protection: increasing production capacities with increased plant efficiency in larger production environments with unavoidable gas and dust exposure. For example, the chemical industry, the textile industry or the wood processing industry are increasingly demanding safety-related components with additional ATEX certification. As a specialist for safe sensors, TWK is happy to meet this demand and expands its portfolio every year with several new sensors that meet these requirements.

Arbitrary mounting is made possible by the use of MEMS sensors. The rotor hub sensor contains a high-precision gyroscope sensor that measures the applied speed (angular velocity). An additionally installed accelerometer serves to validate the speed signal and outputs the current angle on the 360° scale as the rotor position.
The interface of the sensor is PROFIsafe via PROFINET, additionally equipped with the PROFINET standard module. This device was developed as a functionally safe safety version according to ISO 13849 and IEC 61508 with Performance Level d and Safety Integrated Level 2 with a service life of 25 years. Now the certificate from the TÜV certification body is also available. The user can be sure that he is installing a safe sensor that delivers reliable data. And in a double sense: metrologically and functionally safe.
The fact that the sensor can be mounted anywhere in the rotor of a wind turbine or in a similar application - without the need for a shaft connection - makes it much easier for the user to use. It required a new approach to measured value processing during development. The implementation of a Kalman filter for linking the measured values of the gyroscope and the accelerometer, as well as newly developed algorithms and correction filters, finally produced a very good result: a fast-responding and interference-tolerant speed signal of high accuracy. So far unique on the market. The typical longitudinal and transverse vibrations occurring in a wind turbine as well as nacelle vibrations have little effect on the quality of the signal. Many tests in the laboratory and in the field were successfully passed, even with slight tilting from the plane of rotation. The measure of all things here was the high requirements of our customers. The first series applications have already been carried out.
The robust and weather-resistant sensor thus contributes to the safe operation of a wind turbine, for example to prevent damage caused by overspeed of the rotor. With its sturdy aluminium housing, it offers protection class IP67. The connection is made via M12 plugs.