Due to the extreme conditions faced by humans and machines alike, particularly stringent safety regulations apply to plant and systems operated in heavy industry. To fulfil these requirements Johannes Hübner Fabrik elektrischer Maschinen GmbH offers the EGS(H) 41 electronic overspeed switch that operates independent of the closed-loop speed control system. The EGS(H) 41 is certified up to Safety Integrity Level (SIL) 2 in accordance with the international standard IEC 61508 as well as up to Performance Level (PL) d to DIN EN ISO 13849. The EGS(H) 41 is the only overspeed switch worldwide certified to this standard. Consequently, it guarantees the operator the highest level of plant safety and serves to protect personnel.
Monitoring speed and safety functions
With an integrated sensor, logic circuitry and an actuator the EGS(H) 41 functions as a complete system. The speed is sensed, evaluated and switched in sequence. The safety device is equipped with two separate, electrically isolated and, as a consequence, complete switches to monitor speed that can be programmed independent of one another to monitor overspeeds and underspeeds from 0.5 rpm. In this instance the electrical insulation generates a huge advantage in comparison with mechanical centrifugal switches, which would need a second device for the same function. A further switch automatically monitors safety functions relevant to the hardware and software modules (diagnostics). The EGS(H)® 41 also features integrated overcurrent detection and monitors the status of the wear-free, electronic switching contacts as well as optional standstill and slip monitoring.
High levels of safety for heavy industry
Johannes Hübner Giessen developed the device specifically for use in heavy industry, such as steel and rolling mills, crane systems and the mining industry. The protective measures put in place in those fields within the concept of "functional safety" are responsible for the proper functioning of safety-related systems to reduce risks. Hence, according to international standards the systems must carry out their functions under defined fault conditions with a defined high degree of probability.
Ideal combination: ASPAH 60 and EGSH41 mounted securely up to PL e
Johannes Hübner Giessen offers suitable accessory components to securely mount the EGSH 41 up to Performance Level (PL) e. The components with failure exclusion guarantee are available to securely mount an individual device as well as a combination of the EGSH 41 and the new absolute encoder ASPAH 60. This compact and robust combination of devices is often deployed on main drives in heavy industry applications. The ASPAH 60 automatically provides an absolute value (parallel interface) at the first terminal box to control the position of the pulse wheel as well as two electrically isolated signals in the second terminal box to control the speed and for higher level automation purposes. Equally equipped with two terminal boxes the EGSH 41 has four programmable safe switching outputs; these can be used, for example, to monitor standstill status, safety limited speeds and impose overspeed protection requirements.