Non-stop bus operation

Horst Kalla

Profibus-PA is an open field bus standard (EN 50 170, IEC 1158-2, DIN 19 245). It was designed especially for the requirements of process automation, which include remote supply and intrinsic safety. Profibus-PA permits several sensors and actuators to be operated on one common bus line. The devices are supplied with power via 2-wire technology and the process data is communicated digitally.Profibus-PA is a preferred choice due to its flexibility – nearly all topologies are permitted. The workstations in a Profibus-PA installation topology communicate mainly along a direct route. The bus line is connected directly to the respective stations and routed on to the next device. The disadvantage: direct connections lead to increased installation times since the power supply and data supply have to be disconnected every time a component is replaced or maintenance work is carried out. This is where the PA-T connector comes into action. The T connector maintains a continuous connection to the other bus stations even when modifications or maintenance tasks are being performed on the installation.

The PA-T connectors comply with the IP 67/IP 66 degree of protection, and special versions are available with an external ground connection, an internal pressure compensation element, EMC glands or overvoltage protection. With the exception of the Ex i version, these connectors are equipped with a built-in RC bus terminator, which can be selected or deselected via a jumper. The Eex(ia) version fulfils the safety regulations in areas subject to explosion hazards, i.e. Zones 0 + 1 (Certificate of Conformity PTB No. Ex-98.E.2041).

The handling benefits and installation costs of these T connectors from the interface specialists are just as convincing as the range of available products. Plant fitters can integrate the coupling elements into the bus either via positioning connectors – for a direct coupling to field devices – or via stub lines and connectors. The connectors are ready to use immediately and provide a continuous connection between the bus stations at all temperatures between -40 °C and +85 °C, as well as during maintenance work of course.The T connectors are protected from external damage by an aluminium housing.

They have proved their “connection talent“ in a variety of applications in the foodstuffs, raw materials and chemical industries around the globe. The American Brewing Group Anheuser Busch, Wacker Chemie, Shell and the Bitburger Brewery in Germany are just a handful of the customers where the T connector is in action.

Weidmüller

Fax: ++49/5231/14 11 03

Further information cpp-205