In safety critical applications, the ability to predict the shielding effectiveness of reinforced... more In safety critical applications, the ability to predict the shielding effectiveness of reinforced concrete structures during the preliminary stages of an architectural design is fundamental in achieving an EMC compliant design. The prediction tools must be simple and easy to use, as in most cases architectural designs are usually performed by non-EMC specialists. This paper proposes a simple analytical approach which provides an approximate evaluation of the attenuation due to reinforced concrete walls. The influence of moisture content (MC) and wall thickness is easily demonstrated. Comparison with numerical analysis is provided
ABSTRACT The characterization of integrated electronics system performance to electromagnetic dis... more ABSTRACT The characterization of integrated electronics system performance to electromagnetic disturbance is receiving increasing focus particularly systems performing safety related functions. The increased focus is driving the need for standardized EMC performance requirements in terms of test limits for associated electromagnetic disturbances. This paper reviews the philosophy underpinning EMC standards at component level (ICs) and those at system level; it describes the challenges facing the development of standards for EMC and Functional Safety. It also describes the work of IEC SC65A WG4 in developing EMC and Functional Safety standards for safety related systems.
ABSTRACT DC electrified traction systems are a potential source of stray current, that may corrod... more ABSTRACT DC electrified traction systems are a potential source of stray current, that may corrode both internal and external metal structures and installations. The stray current intensity depends on several factors (such as traction current, rail insulation, concrete mat and pier resistance) that need to be accounted for in any model for the estimation of stray current. The effect of an uniform or multilayer soil in such predictive model is of equal importance. In practice, there are numerous models that have been developed to investigate railway stray current phenomena; these models can be categorized into two - namely distributed parameter model and lump parameter model - based on the parameter model used. In this paper, both models are compared to highlight the differences between both methods.
ABSTRACT The Northern Line track circuit based train control system is being replaced with a tran... more ABSTRACT The Northern Line track circuit based train control system is being replaced with a transmission based train control system. A key objective of this change is achieving system compatibility without adversely impacting the operational railway. This paper focuses on the design for system compatibility between the 95TS and Alcatel's Seltrac TBTC system, describing the interference issues encountered and the implementation of cost effective design solutions to achieve system compatibility
Africa is an import oriented continent with a significant percentage of all electronics and elect... more Africa is an import oriented continent with a significant percentage of all electronics and electrical equipment imported, as new or second hand, from other developed nations. The explosion of the telecommunications industry in Africa is an indication of the potential market in this great continent, with an estimated market of 15 million subscribers to GSM technology in Nigeria alone. As Africa increases its participation as users (and most importantly as stakeholders) of technology, the importance of electromagnetic compatibility and bio-electromagnetics increasingly becomes an issue. The paper describes EMC, its potential impact and the need for regulation in an increasing industrialized Africa
ABSTRACT An electrified railway is an electromagnetically complex installation due to its physica... more ABSTRACT An electrified railway is an electromagnetically complex installation due to its physical size, the interaction between its constitute parts and the electromagnetic interference coupling mechanisms between these parts. The complexity of the installation requires proper management and understanding of the electromagnetic disturbance that may compromise the safety and operational integrity of the railway infrastructure. Increasingly, over riding safety requirements demand an analysis of all credible failures, due to electromagnetic interference, under normal or abnormal operation. Such analysis lends itself to the application of analytical methods to support the measurement efforts. This work reviews the physics of the electromagnetic coupling between an AC electrified railway and nearby earth return circuits. It covers the application of transmission line theory to describe the conductive and inductive coupling mechanism that exist between railway traction and nearby buried signaling conductors.
Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands ... more Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands a detailed understanding of its electrical properties. Besides experimental measurements, material theoretical models can be useful to investigate its behaviour with respect to frequency, moisture content or other factors. These models can be used in electromagnetic compatibility (EMC) to predict the shielding effectiveness of a concrete structure against external electromagnetic waves. This paper presents the development of a dispersive material model for concrete out of experimental measurement data to take account of the frequency dependence of concrete's electrical properties. The model is implemented into a numerical simulator and compared with the classical transmission-line approach in shielding effectiveness calculations of simple concrete walls of different moisture content. The comparative results show good agreement in all cases; a possible relation between shielding effectiveness and the electrical properties of concrete and the limits of the proposed model are discussed.
The prediction of the shielding effectiveness of concrete structures is a fundamental aspect of t... more The prediction of the shielding effectiveness of concrete structures is a fundamental aspect of the architectural design phase of purpose built control centres. These buildings designed with a functional requirement to house sensitive control equipment; malfunction of such equipment may lead to loss of life and impact on revenue service. In this paper, a simple analytical approach is proposed to influence the design of buildings such that the structure provides adequate attenuation to hostile electromagnetic ambient and potential electromagnetic pulses. Comparison with numerical methods is provided. The effect of moisture content on the shielding effectiveness of a concrete wall is outlined.
This paper deals with the issue of demonstrating electromagnetic and signalling compatibility bet... more This paper deals with the issue of demonstrating electromagnetic and signalling compatibility between two train control systems. In particular, the paper presents an analysis of mutual coupling between a legacy track circuit based train control system (TCS) and a transmission based train control (TBTC) system. The analysis focuses on the ability of the TBTC system to adversely impact the operation of the track circuit based TCS. The paper presents measurement and computational data, and concludes that due to the weak coupling between the TBTC and track circuit TCS, the induced voltage (and current) in the legacy system due to the TBTC does not present a EMI risk to the safe operation of the track circuit TCS.
In safety critical applications, the ability to predict the shielding effectiveness of reinforced... more In safety critical applications, the ability to predict the shielding effectiveness of reinforced concrete structures during the preliminary stages of an architectural design is fundamental in achieving an EMC compliant design. The prediction tools must be simple and easy to use, as in most cases architectural designs are usually performed by non-EMC specialists. This paper proposes a simple analytical approach which provides an approximate evaluation of the attenuation due to reinforced concrete walls. The influence of moisture content (MC) and wall thickness is easily demonstrated. Comparison with numerical analysis is provided
ABSTRACT The characterization of integrated electronics system performance to electromagnetic dis... more ABSTRACT The characterization of integrated electronics system performance to electromagnetic disturbance is receiving increasing focus particularly systems performing safety related functions. The increased focus is driving the need for standardized EMC performance requirements in terms of test limits for associated electromagnetic disturbances. This paper reviews the philosophy underpinning EMC standards at component level (ICs) and those at system level; it describes the challenges facing the development of standards for EMC and Functional Safety. It also describes the work of IEC SC65A WG4 in developing EMC and Functional Safety standards for safety related systems.
ABSTRACT DC electrified traction systems are a potential source of stray current, that may corrod... more ABSTRACT DC electrified traction systems are a potential source of stray current, that may corrode both internal and external metal structures and installations. The stray current intensity depends on several factors (such as traction current, rail insulation, concrete mat and pier resistance) that need to be accounted for in any model for the estimation of stray current. The effect of an uniform or multilayer soil in such predictive model is of equal importance. In practice, there are numerous models that have been developed to investigate railway stray current phenomena; these models can be categorized into two - namely distributed parameter model and lump parameter model - based on the parameter model used. In this paper, both models are compared to highlight the differences between both methods.
ABSTRACT The Northern Line track circuit based train control system is being replaced with a tran... more ABSTRACT The Northern Line track circuit based train control system is being replaced with a transmission based train control system. A key objective of this change is achieving system compatibility without adversely impacting the operational railway. This paper focuses on the design for system compatibility between the 95TS and Alcatel's Seltrac TBTC system, describing the interference issues encountered and the implementation of cost effective design solutions to achieve system compatibility
Africa is an import oriented continent with a significant percentage of all electronics and elect... more Africa is an import oriented continent with a significant percentage of all electronics and electrical equipment imported, as new or second hand, from other developed nations. The explosion of the telecommunications industry in Africa is an indication of the potential market in this great continent, with an estimated market of 15 million subscribers to GSM technology in Nigeria alone. As Africa increases its participation as users (and most importantly as stakeholders) of technology, the importance of electromagnetic compatibility and bio-electromagnetics increasingly becomes an issue. The paper describes EMC, its potential impact and the need for regulation in an increasing industrialized Africa
ABSTRACT An electrified railway is an electromagnetically complex installation due to its physica... more ABSTRACT An electrified railway is an electromagnetically complex installation due to its physical size, the interaction between its constitute parts and the electromagnetic interference coupling mechanisms between these parts. The complexity of the installation requires proper management and understanding of the electromagnetic disturbance that may compromise the safety and operational integrity of the railway infrastructure. Increasingly, over riding safety requirements demand an analysis of all credible failures, due to electromagnetic interference, under normal or abnormal operation. Such analysis lends itself to the application of analytical methods to support the measurement efforts. This work reviews the physics of the electromagnetic coupling between an AC electrified railway and nearby earth return circuits. It covers the application of transmission line theory to describe the conductive and inductive coupling mechanism that exist between railway traction and nearby buried signaling conductors.
Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands ... more Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands a detailed understanding of its electrical properties. Besides experimental measurements, material theoretical models can be useful to investigate its behaviour with respect to frequency, moisture content or other factors. These models can be used in electromagnetic compatibility (EMC) to predict the shielding effectiveness of a concrete structure against external electromagnetic waves. This paper presents the development of a dispersive material model for concrete out of experimental measurement data to take account of the frequency dependence of concrete's electrical properties. The model is implemented into a numerical simulator and compared with the classical transmission-line approach in shielding effectiveness calculations of simple concrete walls of different moisture content. The comparative results show good agreement in all cases; a possible relation between shielding effectiveness and the electrical properties of concrete and the limits of the proposed model are discussed.
The prediction of the shielding effectiveness of concrete structures is a fundamental aspect of t... more The prediction of the shielding effectiveness of concrete structures is a fundamental aspect of the architectural design phase of purpose built control centres. These buildings designed with a functional requirement to house sensitive control equipment; malfunction of such equipment may lead to loss of life and impact on revenue service. In this paper, a simple analytical approach is proposed to influence the design of buildings such that the structure provides adequate attenuation to hostile electromagnetic ambient and potential electromagnetic pulses. Comparison with numerical methods is provided. The effect of moisture content on the shielding effectiveness of a concrete wall is outlined.
This paper deals with the issue of demonstrating electromagnetic and signalling compatibility bet... more This paper deals with the issue of demonstrating electromagnetic and signalling compatibility between two train control systems. In particular, the paper presents an analysis of mutual coupling between a legacy track circuit based train control system (TCS) and a transmission based train control (TBTC) system. The analysis focuses on the ability of the TBTC system to adversely impact the operation of the track circuit based TCS. The paper presents measurement and computational data, and concludes that due to the weak coupling between the TBTC and track circuit TCS, the induced voltage (and current) in the legacy system due to the TBTC does not present a EMI risk to the safe operation of the track circuit TCS.
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Papers by Ade Ogunsola