文档介绍：Section 1
EMC OF ELECTRICAL POWER EQUIPMENT
MUTUAL INDUCTANCE BETWEEN WIRES IN HELICALLY
TWISTED POWER CABLES
Bernd W. Jaekel, Germany
Siemens AG, Automation and Drives, Germany, e-mail: @
Abstract. The arrangement of the conductors in a multi-core power cable leads to a situation where various conductor loops are built up. One or several loops are formed by the phase and neutral conductors with the operational current flowing in these conductors. A further loop is built up by the protective earth conductor which is connected to the equipotential bonding system at several locations. The area of this loop is essentially arranged outside of the power cable. The inductive coupling from the phase conductor loops into that loop mon mode voltages in the protective earth system with mon mode currents. It can be demonstrated that this effect even takes place in the case of balanced phase currents in the cable. Numerical simulations and parameter studies were carried out in order to describe this effect quantitatively and to investigate the influence of different cable parameters onto the mon mode voltages.
Introduction
Power cables ponents of an entire power work which can be carried out in different types. If an earthed system is required, . a system which is connected to the local reference earth, mainly two types of works can be distinguished: TN-C and TN-S. From an EMC point of view a TN-S work should definitely be preferred [1]. In this type work the neutral and protective earth (PE) conductors are strictly separated except at point where both conductors are connected, normally at the transformer or the switchgear. This type of installation prevents that any operational currents flow outside of the phase and neutral conductors. No currents should exist and therefore the equipotential bonding system is generally assumed to be free of any operational currents. But when looking in more detail at this type work and at the physical structure of pow