Process control systems are deployed in process engineering and power generation systems. Despite the availability of alternative technologies such as remote I/Os and field buses - incoming and outgoing signal connections are often connected via terminal blocks housed in routing and distribution cabinets. A number of advantages favour the use of terminal blocks, for instance they are equipped with an uncomplicated connection technology and ensure a clear arrangement of electrical systems. And by making use of different accessories terminal blocks can be adapted to provide the best possible solution for the respective application. Fuse holders plugged onto terminal blocks protect signal lines, whilst extensive identification marking possibilities take the stress out of service and maintenance tasks as well as facilitating successful troubleshooting.
To facilitate simple and precise routing and distribution of electrical signals the new family of 'WMF' terminal blocks have been designed for deployment in routing and distribution cabinets. As well as equipping the terminals with feedthrough, fuse and disconnect functions Weidmüller designed the 'WMF' family with a compact width of 5 mm and a uniform design appearance. The integrated shield or PE connection replaces shield connection equipment or PE terminal blocks. Weidmüller has introduced an innovative solution for routing and distributing signals. Instead of contacting each individual signal by means of a screw connection between the routing levels it is possible to use preassembled cable sets terminated with 'BLZ' connectors. Simply plug the connector onto the terminal block ? Plug and Play - that reduces valuable wiring time. The blackcoloured fuse terminals are equipped with a newly developed, robust, pivoted fuse holder. Changing fuses is an extremely simple procedure, because the fuse can be very quickly replaced when the rotatable holder is open and facing upwards. Precise and safe handling is a clearcut distinguishing feature in comparison with systems of the same size available to date. An optional LED status indicator on the fuse terminals indicates clearly - the fuse is OK or defective. The LEDs utilised have a high luminous power, minimal leakage current characteristics of <0.5 mA and do not interfere with signals in the control circuit. Guaranteeing high levels of flexibility when bundling and looping through potentials the crossconnection channels are characteristic of the 'WMF' terminal blocks. In addition to the neutral conductor the user is able to collect an additional shield potential across a large number of poles by utilising standard 'ZQV' crossconnectors.
Tried and trusted millions of times over the 'WMF' family of terminal blocks is equipped with the world renown clamping yoke (screw) connection system. The gastight clamping yoke system is shake and vibration proof; moreover, it is maintenancefree, low resistant and offers both a high and permanent contact force. Utilising the clamping yoke system makes it possible to connect two conductors at a single terminal point. The connection system utilised on the 'WMF' terminal blocks can accommodate the following conductor sizes and conductor crosssections: solid and flexible conductors between 0.5 - 4 mm2, stranded conductors between 1.5 - 4 mm2 and conductors with ferrules between 0.5 - 2.5 mm2.
Users can take advantage of Weidmüller's diverse programme of accessories to adapt the 'WMF' family of products to achieve the best possible solution for their application. 'SIHA 3' fuse holders for 5 x 20 fuse cartridges are available to protect signal lines. The 'SIHA 3' is available with and without a red LED.
Marking channels accommodate unambiguous and clearly visible markings to identify electrical equipment. This design feature serves to increase clarity of the wiring in the routing and distribution cabinet as well as ensuring clearcut identification of signal circuits.
The 'WMF' family of terminal blocks is made of the highlyresistant insulating material WEMID - this is a special thermoplastic from Weidmüller that in comparison with polyamide PA 66 offers an enhanced continuous operating temperature of 120 °C (PA 66: 100°C). At the same time it exhibits improved fire resistance qualities (flammability class V0 (PA 66: V2) in accordance with UL 94.
For more information: www.weidmueller.com and www.power-signals-data.com
Captions:
Fig. 1: Weidmüller's 'WMF' terminal blocks: The new terminal blocks facilitate simple and precise routing and distribution in process engineering plants and power generation facilities. Detail 1: changing fuses is fast and precise thanks to the pivoted fuse lever. Detail 2: Simply plug the 'BLZ' connector onto the terminal block ? Plug and Play - that reduces valuable wiring time.
Fig. 2: Weidmüller's 'WMF' terminal blocks: The three crossconnection channels of the 'WMF' terminal blocks ensure high levels of flexibility when bundling and looping through potentials.