Explosive atmospheres are a special field in heavy industry subject to stringent safety requirements. With this in mind Johannes Hübner Giessen developed the incremental encoder Ex FG 40 for applications in extremely harsh environments and stringent explosion protection requirements. These include explosive gas environments such as in the production of oil and gas on platforms and offshore drilling rigs, petrochemical plants, oil and gas processing, paint shops in the steel sector as well as application fields with explosive dust atmospheres such as in mining and bulk materials handling terminals.
Dual certification to ATEX and IECEx
The Ex FG 40 is certified according to both the latest Directive ATEX 2014/34/EU across the European countries as well as the international IECEx concept for Zones 1 and 2 (gas) and Zones 21 and 22 (dust); the precise marking is: II 2G Ex db IIC T6-T5 Gb (gas) and II 2D Ex tb IIIC T85°C Db IP6x (dust). Dual certification means it is possible to deploy the Ex FG 40 in a very large number of countries without the need for additional national certificates of conformity. The device is built to achieve protection level db (flameproof enclosure) for gas-laden environments and tb (protection by enclosure) for dust-laden environments.
Extremely robust, user-friendly connection options
The Ex FG 40 is a further development of the standard Hübner encoder FG 40, from which the electronics are derived. In contrast, the mechanical components are completely new. Distinguishing features of the device are its extremely rugged construction thanks to the thick-walled enclosure, a long service life due to the large ball bearings and robust stainless steel shaft with feather key, its resistance to shock and vibration as well as the high-level of corrosion protection thanks to the high-quality anodic coating. Despite the high protection class IP66 the Ex FG 40 offers a wide speed range up to 6000 rpm as well as suitability for an ambient temperature range of -40 °C to +60 °C. It is possible to deploy the device up to 4000 m AMSL.
In addition, the device is made of salt-water proof aluminum, which ensures it is predestined for use on offshore drilling rigs and in harbour facilities. The user-friendly wiring option is a particularly special characteristic, for which there is sufficient space in the large terminal box. The flange attachment option with 30° grid alignment makes it possible to install the encoder perfectly aligned to the lay of the cable. Since the terminal box cover can be removed from the rear of the Ex FG 40 the user is able to terminate the wiring for the power supply and signals according to requirements. That facilitates variable cable lengths; completely sealed devices can only offer a predetermined fixed cable length. If the user has several encoders in use, for example installed at various motors, the latter means he will have to carry a large stock of individual device types with different cable lengths. Installing the Ex FG 40 means it is possible to reduce the variety of versions and lower the costs for spare parts as a consequence.
Two redundant output signals possible
It is possible to deploy the Ex FG 40 with dual signal output for applications requiring a second output signal. A second output signal can be required, for example, for higher-level controls or as a redundant signal where increased safety requirements are imposed. The dual signal output means the user does not need to install a second encoder or an additional pulse splitter. The dual signal output is optionally available with HTL, TTL or sinus signals. Utilizing precision optical scanning the Ex FG 40 generates a very high signal quality, with up to 1 million pulses per rotation. The maximum transmission frequency is up to 200 kHz.