IEEE Std 1407:2007 pdf free download

IEEE Std 1407:2007 pdf free download.IEEE Guide for Accelerated Aging Tests for Medium-Voltage (5 kV-35 kV)Extruded Electric Power Cables Using Water-Filled Tanks.
Silane-curcd XLPE does not use dicumyl peroxide as the curing agent and thus contains different cross- linking by-products. No data are available at this time on the effects of the by-products for silane-cured insulation and the procedures in this clause may not bc applicable to silanc-cured XLPF.. Also no data arc available in the published literature on the effect of cross-linking by-products on EPR-insulated cables.
Although their effects on the performance of extruded cable insulation are not precisely known, there is sufficient published data, at least for steam-cured XLPE. to show that an increased concentration of byproducts improves the resistance of the insulation system to water treeing and that the concentration of byproducts in XLPE gradually decreases with time, e.g.. the concentration of cross-linking by-products in 15 kV XLP[ cable may be less than 100 ppm after 10 years in service and, as a result. may not contribute to the tree retardancy. However, in accelerated aging tests lasting a year or even longer, if the accelerated temperature does not drive off the cross-linking by-products, an apparent improved resistance of the insulation to water treeing could result. Thus the long-term behavior, for the insulation rith a low concentration of by-products. may not be as good as that predicted by the results of the accelerated aging test. To reduce this possibility the cables are preconditioned in order to reduce the amount of by-products in the insulation before being subjected to the aging test. The most common form of preconditioning is to subject the cables to elevated temperatures, either by conductor heating or oven heating, to increase the rate of diffusion of the by-products from the insulation.
In addition to remoing the by-products. elevated-temperature preconditioning can:
– Cause chemical changes in the insulation depending on the temperature employed.
Cause morphological changes in the insulation due to partial melting and recrystallization.
These changes can also affect the water treeing and long-term behavior and contribute to making preconditioning and its influence a very complex issue. Although the effects on XLPE are only partially understood, and the effects on TRXLPE and EPR are understood to a lesser extent, some form of preconditioning is preferred to reduce the level of by-products as long as the other changes mentioned here do not alter the mechanism of aging and loss of 1it. The preconditioning described here is based on limited measurements on 15kV XLPE cables with no strand blocking (Abdolall [Bl]), Martin and Hartlein 1H191, Plissou 1B231) and its aim is to reduce the level of the cross-linking by-products to less than 100 ppm. The choice of 100 ppm is based upon a limited number of measurements on cables that had been in service for up to 10 years and may have to be modified as more information becomes available. The procedure may not be suitable for silanc-cured XLPE. TRXLPE, or EPR cables, as no measurements have been made to determine the level of cross-linking by-products in service-aged cables with these insulations, nor tests performed to determine the rates at which the by-products diffuse from these types of cables at elevated temperatures. In view of the unknowns, users should be cautious in interpreting the data.