TWK completes its range of NOC electronic cam switches. The established NOCE model with SSI interface is extended by the PLd certified variant according to EN ISO 13849-1:2015. Safe switching contacts supplement the position signal of the integrated encoder to enable the cam controller to be used in safety-critical applications - primarily in the wind industry.
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.
