WCA July 2007

Technology News

By helping cable products meet their technical specifications, Cropico precision measurement instrumentation also ensures that valuable copper raw material is used efficiently. The in-line installation of Cropico D05000 microhmmeters as part of copper cable production facilities enables highly accurate low resistance measurements to be undertaken to ensure that products meet relevant technical performance standards and specifications. Installation of the D05000 in-line as part of the production process also eliminates waste material by cutting off cable samples and then scrapping the offcuts. In addition, by constantly monitoring the resistance value of the cable, the system also ensures the cost effective use of copper raw material in the manufacturing process. Given the relatively high price of copper, this factor is a significant consideration in the cable manufacturing process. All cable products are designed and manufactured to close electro- technical tolerances in keeping with the requirements of a host of international product and performance standards. The cable’s resistance value is critical in this respect – if resistance is too high, then the current carrying capability of the cable is reduced. Since cable resistance reduces as the diameter is increased, it is important that the specified resistance per metre is achieved in relation to the optimum diameter of the cable. Being too generous with the cable diameter means more copper is being used than necessary. As copper is the main contributor to the cost of a cable, for maximum manufacturing cost efficiency it is crucial that the required resistance is achieved with the minimum cable diameter. The D05000 uses true four-wire Kelvin resistance measurement technology to eliminate lead resistance errors. This system, alongside auto averaging of test current and automatic temperature compensation, ensures the highly accurate measurement of resistance in the cable during the manufacturing process. Precision increasing efficiency

Making savings on raw materials

▲

In typical manufacturing environments, the Cropico D05000 is linked to a specialist clamp which holds a standard 1 metre length of cable or wire in place as the copper strands pass along the bobbin extruder. The clamp incorporates separate current and potential measurement connections, which are attached to the cable for resistance measurements to be made. There are three cable models in the Cropico range and these offer the ability to accurately clamp and measure cable up to 1,000mm 2 . There is a model that has an integrated water bath which will automatically bring the cable under test to a specific temperature. Programmable current levels and the selection of different test speeds give the Cropico tester flexibility to accurately measure the resistance values of different cable products. These include single end and plain soft wires through to bunched, stranded and large diameter rope type conductors. Accurate and reliable in-line cable resistance measurements taken in this way enable cable manufacturers to maintain optimum operating efficiencies in terms of copper raw material use. There are four models in the D05000 series which form part of a comprehensive range of microhmmeters and precision measurement instrumentation.

Cropico Ltd – UK Fax : +44 191 586 0227

Email : williame@seaward.co.uk Website : www.cropico.co.uk

49

Wire & Cable ASIA – July/August 2007