The rule-based approach, i.e. following electromagnetic interference standards, is the basic methodology assumed to result in electromagnetic compatible systems operating properly in their intended environment. For complex systems we need a smarter approach, based on assessing and controlling the electromagnetic risks. This risk-based approach is described, and applied to naval ships.
A major objective of TEMPEST engineering is to separate equipment carrying classified ( = RED) data from equipment carrying unclassified (= BLACK) data, to prevent unintentional radio or electrical signals, containing classified data, emission. RED/BLACK separation in the power supply system is in general achieved by adding TEMPEST filters, but on board naval vessels the power system is insulated and the use of filter capacitances is limited. Solid-state uninterruptable power supplies (UPS) create isolation, because of the AC/DC and DC/AC conversion and associated internal filtering. Measurements have been performed on an operational UPS to determine the a-symmetrical, symmetrical and non-symmetrical isolation. The results obtained from the UPS tested show very good isolation which, combined with the already installed power line filters inside equipment, will be more than adequate to achieve the required isolation for RED/BLACK separation.
The use of commercial off the shelf (COTS) devices have become a preferred strategy in ship system developments. In this work, we investigated the behavior of an uninterruptible power supply (UPS) using COTS-based equipment on a ship's power distribution system. It focuses on the implementation of IEC 60092-101 and STANAG 1008 Ed. 9 frequency tolerance requirements. One of the important benefits of this work is that it can be used as a consideration for the electromagnetic risk of integrating COTS-based equipment in an islanded power system like ships. The voltage and current behavior of the equipment under test were measured and recorded at four different points simultaneously using a multipoint measurement technique. From the analysis, it was found that when the frequency of the mains supply is deviated by 5 % the current at the UPS input is modulated and the maximum current is increased.
A behavioural model for performance evaluation of a common mode choke (CMC) is proposed: the topology and methods used to model the different properties of the CMC are presented. It combines an accurate model of the complex permeability, of the saturation, of leakage inductances and of parasitic capacitances. Inputs needed from the designer are measured values of currents, voltages and impedance of the actual system, and parameters available in literature and/or from manufacturers for the modelled CMC. The behavioural model is essential in simulation of EMI effects.
Electromagnetic interference (EMI) can degrade the power quality (PQ) in an electrical network. Identification of the interference source and its propagation can only be achieved by distributed measurement methods using synchronous multipoint measurements. This paper proposes a multipoint measurement analysis method using the number of coincidence events and a coincidence ratio to determine the relationship between each EMI event at several measurement locations. The measurement is performed using six distributed power quality analyzers.
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