Medium Voltage Cable Shield Grounding

This article discusses the medium voltage mv or high voltage hv cable shield grounding or termination methods.

Medium voltage cable shield grounding.

Grounding methods and requirements for systems operating at more than 1 000 volts v such as 5 and 15 kilovolt kv systems differ slightly from those for systems of 1 000v or less. The nec provides several rules related to the grounding of these systems and associated equipment. Medium high voltage cable types of the nearly limitless variety of cables in use today five of the most common are. The authors describe the purposes of the shields conductor shield insulation shield and metal shield in medium voltage cables.

It is noted that in essence the conductor shield is an electrical extension of. Single conductor. Shield losses shield grounding and shield terminations are also discussed. If an unshielded insulated cable is in contact with earth or a grounded object the electrostatic field around the conductor will be concentrated at the contact point resulting in corona discharge.

Tape shielded drain wire shielded general cable unishield concentric neutral cn jacketed concentric neutral jcn beyond cable shield types two common configurations are used. Systems in these voltage ranges are commonly referred to as medium voltage systems. Installing medium voltage power cables underground comes with its own set of challenges. That of carrying a portion of return ground fault current.

With its extensive technical and engineering expertise and a state of the art compound facility general cable is committed to using materials with the best overall properties to create the most comprehensive line of industrial power cables to meet your design requirements. General cable is recognized as a world class leader in the development and design of medium voltage industrial cables. From an engineering standpoint there are several factors one needs to consider before installing the cable. Verification of shield performance under ground fault conditions will prevent systemwide cable damage as we all know the metallic shielding in a medium voltage mv cable provides the necessary uniform electric field within the cable s insulation.

What is not as well known is its other equally important function. Shielding of electric power cable results in symmetric electric field distribution within the cable insulation and prevents stress damage. Medium and high voltage power cables in circuits over 2000 volts usually have a shield layer of copper or aluminum tape or conducting polymer.