title: An analysis of pulse transformers

authors: Harrison, Craig Brendon

abstract: This thesis focuses on developing a comprehensive understanding of the behaviour of the output pulse transformer used in an electric fence energiser, a unique application which has received little attention in the literature.

Maxwell’s Equations form the starting point for an investigation into the magnetisation of the magnetic core under high current pulse conditions. An equation is derived which describes the time dependent nature of the penetration of the magnetic field into the core material. The concept of a region of high permeability moving into the lamination as a result of rapid saturation is also developed.

Quantitative results are obtained for the area of this high permeability region, both from the pulse magnetisation equation and by analytical methods. The analytical approach is also used to derive expressions for the pulse current, output voltage and power, and inductance. The analytical model of the output transformer provides much insight into the transformer’s behaviour, and into the influence upon performance of the various circuit elements.

The description of pulse magnetisation is a key factor in the development of both analytical and electrical circuit models of the output transformer.

The final part of the thesis considers the output transformer from the perspective of an electrical circuit model, which is developed as a direct representation of the physical transformer. The inductor-reluctance method is used to develop the model, and methods of calculating each parameter are derived, so that the final model may be obtained directly from the transformer’s specification without the need for experimental measurements. The electrical circuit model is implemented using a SPICE simulator, and an analysis of the transformer highlights the major design parameters.

The description of pulse magnetisation, the analytical model and the electrical circuit model combine to provide a comprehensive description of the behaviour of the output transformer, and provide the tools required for design and further investigation of this application.

text: An analysis of pulse transformers This thesis focuses on developing a comprehensive understanding of the behaviour of the output pulse transformer used in an electric fence energiser, a unique application which has received little attention in the literature.

Maxwell’s Equations form the starting point for an investigation into the magnetisation of the magnetic core under high current pulse conditions. An equation is derived which describes the time dependent nature of the penetration of the magnetic field into the core material. The concept of a region of high permeability moving into the lamination as a result of rapid saturation is also developed.

Quantitative results are obtained for the area of this high permeability region, both from the pulse magnetisation equation and by analytical methods. The analytical approach is also used to derive expressions for the pulse current, output voltage and power, and inductance. The analytical model of the output transformer provides much insight into the transformer’s behaviour, and into the influence upon performance of the various circuit elements.

The description of pulse magnetisation is a key factor in the development of both analytical and electrical circuit models of the output transformer.

The final part of the thesis considers the output transformer from the perspective of an electrical circuit model, which is developed as a direct representation of the physical transformer. The inductor-reluctance method is used to develop the model, and methods of calculating each parameter are derived, so that the final model may be obtained directly from the transformer’s specification without the need for experimental measurements. The electrical circuit model is implemented using a SPICE simulator, and an analysis of the transformer highlights the major design parameters.

The description of pulse magnetisation, the analytical model and the electrical circuit model combine to provide a comprehensive description of the behaviour of the output transformer, and provide the tools required for design and further investigation of this application.

year: 1998

title: Security in Oceania: In the 21st Century (Book Review)

authors: Smith, Ron C.

subjects: security

abstract: Security in Oceania continues to be a pressing problem both for the Island states themselves and for the major countries that form its periphery.  This review surveys the key issues that confront the parties, as seen by participants from the various states who met together at a conference in Honolulu in January 2001.

text: Security in Oceania: In the 21st Century (Book Review) Security in Oceania continues to be a pressing problem both for the Island states themselves and for the major countries that form its periphery.  This review surveys the key issues that confront the parties, as seen by participants from the various states who met together at a conference in Honolulu in January 2001.

year: 2005

title: Using the curriculum guidelines for the teaching and learning of te reo Māori in Years 1 - 13 of New Zealand schools to create lessons for young learners

authors: Diane, Johnson

subjects: New Zealand

abstract: In 2009, The New Zealand Ministry of Education published curriculum guidelines for te reo Māori in Years 1 - 13 of English-medium New Zealand schools, that is, from age 5 upwards. These guidelines recommend a communicative approach to the teaching and learning of te reo Māori. In this article, we discuss communicative approaches and provide examples of ways in which teachers can design communicative language lessons that are appropriate for very young learners, lessons that are not only fun but also effective in developing genuine communicative competence in te reo Māori.

text: Using the curriculum guidelines for the teaching and learning of te reo Māori in Years 1 - 13 of New Zealand schools to create lessons for young learners In 2009, The New Zealand Ministry of Education published curriculum guidelines for te reo Māori in Years 1 - 13 of English-medium New Zealand schools, that is, from age 5 upwards. These guidelines recommend a communicative approach to the teaching and learning of te reo Māori. In this article, we discuss communicative approaches and provide examples of ways in which teachers can design communicative language lessons that are appropriate for very young learners, lessons that are not only fun but also effective in developing genuine communicative competence in te reo Māori.

year: 2009-09