Dependence of Magnetisation near Saturation on Alloying Content in Ferromagnetic Steel

This paper shows that there is strong dependence of saturation magnetization on the alloying content in ferromagnetic steels. This dependence was used to determine the cross-sectional areas of the commercial non-oriented and grain-oriented silicon-iron steels. The relation between magnetization near saturation and the contents of silicon and aluminum for a large number of steel samples was experimentally obtained using an air-cored magnetizing system. The influence of the approach to magnetic saturation and its use in the determination of the cross-sectional area of electrical steel strips using the saturation magnetization method was estimated. Standard deviation (SD) of cross-sectional area obtained using the saturation magnetization method was on the order of 0.14%. SD for using conventional technique was also on the similar order of ~0.11%

Development of an On-Line System for Precision Dimensional Measurements in Electrical Steels using Approach to Ferromagnetic Saturation

A system based on a measurement technique magnetisation near saturation is presented that allows high precision measurement of dimensional parameters of iron alloys. Extensive measurements in electrical steel laminations show high accuracy in measurement of cross section area of the strips. The technique uses approach to saturation magnetisation which has previously been shown to be dependent on alloying content of the materials. This system is proposed for on-line measurement of cross sectional area and thickness of electrical steels, and other types of ferromagnetic strip metals

Modelling of temperature dependence of saturation magnetisa-tion of silicon-iron steels

The temperature dependence of saturation magnetisation of commercial 0.1 to 3 wt. % silicon steels is first measured using an air-cored solenoid and then modelled using a linear formula in accordance with the spin-wave theory, over the range of 20-100°C and in 100 KA/m applied field. The samples measured were heated by applying a heavy ac current along their length, and the measurement of temperature was made using thermocouples. The paper discusses the effect of temperature variation on magnetisation in high field regime approaching saturation in several grades of electrical steel

Modelling of magnetic adhesion robot for NDT inspection of large metal structures

Non-destructive evaluation of structures such as ships and large oil tanks can be rapidly carried out using robots employing magnetic adhesion. This eliminates the need for the use of laborious suction systems, usually employed in climbing robots. However, since the operation of the robot is very much dependent on the speed at which the robot can move before the adhesion is lost, there is a need for determining limits at which magnetic force becomes ineffective. Finite element models and dynamic solution of magnetically supported robots have been presented in order to determine the speed limits at which they can operate

Fault Detection in Aircraft Wiring using Enhanced multi-pulse TDR Technique

Defects in electrical wiring could result in disastrous consequences especially in airborne systems. The defects may in many cases be due to minor damage in the insulation or shielding of wires and cables. This type of defect is not usually detected using routine testing. They may be caused by vibration, moisture, heat, cold, abrasion and other similar effects, causing frays and cracking in wire insulation. Degradation and failure of aircraft wiring insulation is of particular interest which could lead to smoke and fire due to arcing. Results of a technique based on TDR, using trains of successive pulses was previously presented and confirmed through modelling of cables. In this paper the investigation is extended to include small 10 mm and 5 mm holes in coaxial and shielded twisted pair cables. The technique is easy to establish and due to its cumulative nature, can provide higher accuracy with increasing incremental steps. It also holds promise for detection of stray fields for non-contact detection of faults, particularly in shielded cables and wires

Modelling and simulation of fault detection in Shielded Twisted Pair cables

Electrical wiring and cables in many suffer damage from time to time. In many cases the damage only affects wire insulation or the shield section of the cables and cannot be detected under normal operating conditions and maintenance inspection. This could in many cases lead to dangerous incidents. This paper discusses computer models of electrical wires, and in particular Shielded Twisted Pair cables, which can be used for developing systems and test procedures based on an Enhanced Time Domain Reflectometry technique, reported earlier, that could lead to identification and inspection for of this type of fault

Computation of Rectifier Transformers employed in Railway Networks

Many rail transport providers operate and maintain a medium voltage distribution network providing power to trains, signalling equipment and stations. Transformers form an important part of the distribution network stepping voltage up and down. Rectifier transformers are used to provide DC for traction, usually stepping down from medium voltage levels. Mineral oil is essential for optimised performance of large transformers, providing the much needed cooling at high power operation and elevated core and winding temperatures. A representative rectifier transformer has been modelled for a realistic analysis of the 3D model constructed using exact manufacturer’s data for the geometry and coil arrangements. The results are seen to be in good agreement with the actual tests carried out during the commissioning of the transformer

Determination of the Demagnetisation of Electrical Steel Strips

Using basic principles and fundamental equations for calculating the average demagnetising field at the mid-plane of a completely saturated magnetic strip, demagnetising effect was estimated and confirmed by measurements made on various samples. Using the formula, the saturation magnetisation of a group of steel strips, measured using an open magnetic circuit tester, was corrected. The accuracy in determining saturation magnetisation using this method was investigated. © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

Climbing robot design for NDT inspection

Wall climbing robots are extremely useful for deployment in hazardous environments and operation at great heights and other hard to reach space. However, these robots usually require large and heavy suction pads and associated cylinders for supporting the payload and effectual movement during climbing and inspection process and are very difficult to miniaturise. A new type of robot mechanism has been developed where movements are powered by electric motors and hence can be made on a much smaller scale and with the promise of high speed of operation