Informatics Publishing Limited

K. P. Meena ¹, R. Arunjothi ¹, Thirumurthy ¹, G. K. Raja ¹, B. Nageshwar Rao ¹

Affiliations
1 Diagnostic, Cables and Capacitors Division, Central Power Research Institute, Bangalore-560 080, IN

Abstract

Flexible PVC Cables form the major part of Power distribution system within residential buildings, industrial buildings, and other commercial institutions. The ampacity of power cable depends upon the cross sectional area of conductor and the laying and installation of the cable in service. Generally two or more number of PVC cables are bundled together and inserted as a bundle in a conduit pipe for connecting to various load points. As the bundling of cables produce more heat than a single PVC Cable, and dissipation of heat is poor, the ampacity of these cables reduces considerably. Hence the exact selection of sizes and no. of cables are essential to avoid overheating of those cables and the resulting fire havocs.

PVC House wiring cables consists of copper conductor extruded with PVC insulation and are installed generally through a conduit pipe in a bundled manner. The steady state current rating of these cables depends on the way the heat generated in the cable due to current and the heat transmitted to the cable surface & then dissipated to the surroundings. The maximum conductor temperature is limited by the type of insulating material used. In this paper theoretical and experimental results of steady state ampacity ratings of bundles of house wiring PVC Cables laid in conduit pipes are compared.

Keywords

Ampacity, house wiring cables

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K. Mallikarjunappa ¹, Chandrashekar D. Keri ¹, V. Vaidhyanathan ¹, Thirumurthy ¹, T. R. Afzal Ahmed ¹

Affiliations
1 Diagnostic, Cables and Capacitors Division, Central Power Research Institute, Banga, IN

Abstract

Majority of the generating sets operating in our country are turbo generators contributing nearly 70 % of the total electrical power generated. Many of these generators are about 30–40 years old and have already come to the end of their notional design life. The important components that have direct bearing on the operational reliability and life of the machine are: (1) Stator winding, (2) Stator core, and (3) Rotor winding. The stator winding is the most important and expensive part of the generator, where full power is generated. The life of the stator is affected by one or more combinations of various stresses, like electrical, thermal, mechanical and environmental, at any point of time during operation of the machine. Since the mechanical stresses are relatively higher in turbo generators, many of the stator winding failures are mechanically induced electrical failures. Some of the degradation processes include loosening of wedges and coils, slot and end-winding discharges, erosion of stress grading and corona shielding coatings, de-lamination of insulation, de-bonding of copper from insulation, etc.

Keywords

Degradation processes, Insulation resistance and polarisation index, DC Leakage current measurement, Dielectric loss angle, Partial discharge, Surge comparison, Wedge tightness detection, Electromagnetic core imperfection detection

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B. Nageshwar Rao ¹, K. P. Meena ¹, Thirumurthy ¹, G. K. Raja ¹

Affiliations
1 Central Power Research Institute, Bangalore-560080, IN

Abstract

Over the years both due to demand and technological advancements there has been a continuous transition from smaller operating voltages of 6.6. kV to higher voltages of 500 kV. The conventional technology like taping or fi eld moulding are in vogue and new technology like pre-moulded slip on cable accessories are gaining importance for jointing of polymeric high voltage cables up to voltages of 500 kV. The fl ammability characteristics of polymeric materials used in cable insulation and jacketing have been of great importance over the years. Evaluation techniques have become more stringent and both short term and long term tests are conducted in order to ensure the quality of materials used, the manufacturing processes, workmanship and reliability. In this paper the recent advances in HV and EHV power technology is summarized and the experiences in testing and evaluation of 220 kV cables is presented and discussed.

Keywords

Taping, Pre-moulded slip, High voltage (HV), Extra high voltage (EHV) polymeric cables.

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R. Arunjothi ¹, Thirumurthy ¹, P. V. Satheesh Kumar ¹, G. K. Raja ¹, K. P. Meena ¹

Affiliations
1 Central Power Research Institute (CPRI), Bengaluru – 560080, Karnataka, IN

Abstract

In this paper the fire and smoke properties of special application cables such as instrumentation cables, control cables, fibre optic cables and flat travelling cables are compared for their better fire performance. The various outer sheath materials of these cables have been evaluated for its fire performance and as well as smoke performance. In case of zero halogen outer sheath materials of special application cables, only the smoke property is given importance and the fire retardant properties are not being given much importance. Hence the significance of fire retardant property is highlighted in this study.

Keywords

Flammability, Halogen, Instrumentation Cable, Smoke Release, LSZH

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