Solutions for safe speed monitoring

There are many applications where not only the position - for example a set angle - must be transmitted exactly to the controller, but also the adjustment speed - in other words, the speed of rotation as a measure of the speed.

Too slow, too fast or just right? What is the speed? There are many applications where not only the position - for example a set angle - must be transmitted exactly to the controller, but also the adjustment speed - in other words, the speed of rotation as a measure of the speed. Perhaps, in the context of speed monitoring, the speed of rotation is even more important than the corresponding, momentary position. In addition to the property 'exact', i.e. with high accuracy, the property 'safe', i.e. reliable, is also a prerequisite for sensors in a well-designed, safely operating machine.

TWK has now expanded its portfolio with regard to sensors for measuring position and speed. This includes different measuring systems for different types of assembly and measurement requirements. These measuring systems include a high-quality design of the hardware and sophisticated software in order to fulfil the criteria of functional safety according to the standards ISO 13849 as well as IEC 61508, with level PLd or SIL2, in addition to precise position and speed detection. Ideal for speed monitoring in critical applications.

Typical applications are gantry cranes where the travel speed must be recorded. Often on both driven sides, so that it travels evenly. The same applies to crane bridges that travel on permanently installed rails. In addition, the trolley and the load hook must operate at a defined speed in order to reach the targeted positions quickly and safely. Another example is the rotors of wind turbines, which are speed-monitored. Especially with very large rotors, care must be taken that they do not rotate too fast so that the rotor blades do not suffer damage. Safe speed monitoring with "overspeed shutdown" is required.

For these and many other applications, TWK has new encoders, electronic cam switches and rotor hub sensors in its product range - adapted to the customer's installation requirements: For small installation space, there is an ultra-compact FSoE multi-turn safety encoder with a diameter of only 38 mm (TRK38/S3). For the example of rotors, there is a new PROFIsafe rotor hub sensor NBT-D/S3, which is based on the safe inclination sensor NBT/S3 with an additional gyroscope, and does not need a fixed shaft connection for speed measurement. It also does not have to be mounted centrally on the rotary axis.

A wide range of safe interfaces is available: PROFIsafe via PROFINET, EtherCAT FSoE, CANopen safety and others. The cam switch units of the NOCIO79/S3 series with IO-Link interface have implemented safety relays for use in a safety chain. If desired, they switch not only at certain positions, but also when an adjustable speed limit is exceeded - in other words, "Safety First".

PLd certified