IEC TR 61807:1999 pdf download – Magnetic properties of magnetically hard materials at elevated temperatures -Methods of measurement

IEC TR 61807:1999 pdf download – Magnetic properties of magnetically hard materials at elevated temperatures -Methods of measurement.
The present technical report provides methods for measuring magnetically hard materials, at elevated temperatures. Magnetically hard materials (permanent magnet materials) are classified In IEC 60404.1 and their popertles are specified In IEC 604048•1.
The methods of measurement of the magnetic properties of magnetically hard materials at room temperature have been specified in IEC 60404-5 for closed magnetic circuits and in lC 60404-7 for open magnetic circuits, respectively. The applications of magnetically hard materials are now expanding to elevated temperatures and It is therefore required to specify and guarantee the magnebc properties of these materials over their working temperature range.
In lEG 60404-8-1 temperature coefficients of remanence (Or saturation) and J-coercivity have been specified in addition to basic properties such as maximum magnetic energy product ((BH)mix). remanence (Br), B-coercivity (HUB), J-coercivity (Hj), recoil permeability (p,,) and density.
2 Reference documents
IEC 60050(121) :1998, International Electrotechnical Vocabulary (1EV) — Part 121:
Electromagnetism
IEC 60050(151)1 978, International Electrotechnical Vocabulary (1EV) — Chapter 151:
Electrical and magnetic devices
lEG 60050(221 ):1990, International Electrotechnical Vocabulary (1EV) — Chapter 221:
Magnetic materials and components
lEG 60404.1:1979. Magnetic materials — Part 1: Classification
IEC 60404-5:1993. MagnetIc materials — Part 5: Permanent magnet (magnetically hard) materials — Methods of measurement of magnetic properties
IEC 60404-7:1982, Magnetic materials — ParT 7: Method of measurement of the coercivity of magnetic materials in an open magnetic circuit
IEC 60404-8-1:1986, Magnetic materials — Part 8: Specifications for individual materials — Section One: Standard specification for magnetically hard materials
However, in order 10 reduce the size of the apparatus 10 be temperature controlled, a heating system can be inserted between the magnetic poles of an electromagnet, A typical arrangement is shown in figure 1. The results of an inter-comparison in which both heating arrangements were used are given in annex A
The system Shown comprises the upper and lower poles of an electromagnet, each covered with a layer of thermal insulation against which is mounted a pair of heating plates followed by the pair of pole faces which can be made from iron or a cobalt iron alloy. The test specimen together with the J (ol B) sensing coils and the H measuring system are mounted between the measuring pole laces. A hole Is provided in one of the measuring poles for the insertion of a thermocouple to measure the temperature of the pole. It is important that the temperature of the test specimen and pole faces are allowed to stabilize before a measurement is made. Nevertheless, the measured temperature of the pole face and that of the test specimen can be considerably different, the difference being dependent on the geometry and the thermal characteristics of the pole faces and test specimen. It is therefore necessary to establish the relationship between the temperature of the test specimen and pole face In a series of separate experiments.
An alternative method is that based on the method given in IEC 60404-7.A thermallyinsulated heating chamber contains the magnet specimen to be measured, a solenoid, a Bsearch coil and temperature sensor. The procedure is an open-circuit measurement.Themethod of magnetization of the test specimen recommended by industry is a pulse method.Only He.can be deduced using this method.
7 Evaluation of measured data
From a quadratic equation deduced from the values of B, or H. measured at more than threetemperatures, temperature coefficients of B, and Hej can be determined over the temperaturerange between the highest and lowest points by using a statistical calculation.