Analysis of XLPE cable parameters subject to thermo aging

Modern marine vessels use electrically driven rudders; cruise liners, gas carriers, tankers are equipped with Azipod systems manufactured by the Swedish-Swiss company ABB. Gondola-type propellers make it possible to break ice when the vessel is moving astern, therefore such vessels are used for work on the Northern Sea Route, in particular, when working on the Yamal LNG project. The 22MW Azipod propulsion system rotates 360° and enables difficult maneuvering without the assistance of tugs. When operating such propellers, powerful diesel generators are installed on the ship. For the transmission of electricity, ship cables are used, which are subject to increased requirements that meet the standard of the International Electrotechnical Commission. Modern marine vessels are equipped with XLPE or EPDM insulated cable lines; industrial production of these cables is carried out in the Russian Federation. In the course of the study, a method for auditing the state of insulation has been considered based on an assessment of the change in the tangent of the angle of dielectric losses in the process of thermal aging of the cable of the PvBPng(A)-HF brand. Measurements of the tangent of the dielectric losses' angle have been carried out with a Tangens-2000 insulation parameter meter.

Influence of Arc Size on the Ignition and Flame Propagation of Cable Fire

Cable fire caused by arc faults is one of the essential factors threatening the safe operation of a power system. The ignition and flame propagation of cable fire dependent on the characteristics of the arc discharge is lackingin in-depth understanding at present. In this work, with the constant electric power deposited into the arc discharge, the effects of arc size on the ignition and flame propagation of 110 kV XLPE cable fire are investigated for the first time. The arc size is changed by varying the gap distance of electrodes from 1.5 cm to 2.5 cm. It is interesting to find that the larger the arc size is, the faster the cable fire is ignited and propagates, and the larger the damaged area of the sheath of the cable is. Therein, when the gap distance increases from 1.3 cm to 3.1 cm, the equivalent impedance and the length of the arc discharge increase nearly seven times and three times, respectively. However, the gas temperature of the arc decreases slightly from 2280 K to 2100 K. In addition, a 3D model of the cable fire ignited by arc discharge is computed by Pyrosim software with fire dynamic simulation (FDS) module. Simulated results show that as the arc size increases, the cable fire is ignited faster, the flame propagates both vertically and horizontally increasing significantly, which is agreed well with the experimental results. This study deepens the understanding of the cable fire ignited by arc discharge and therefore it is useful for the evaluation and prevention of cable fire.