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4.3: MAGNETIC MATERIALS

By H. Wayne Beaty (eds)
From Standard Handbook for Electrical Engineers, Fourteenth Edition

4.3 MAGNETIC MATERIALS [ ]

4.3.1 Definitions

The following definitions of terms relating to magnetic materials and to the properties and testing of these materials have been selected from ASTM Standard. [ ] Terms primarily related to magnetostatics are indicated by the symbol * and those related to magnetodynamics are indicated by the symbol **. General (nonrestricted) terms are not marked.

**AC Excitation N 1 I/l 1 . The ratio of the rms ampere-turns of exciting current in the primary winding of an inductor to the effective length of the magnetic path.

**Active (Real) Power P. The product of the rms current I in an electric circuit, the rms voltage E across the circuit, and the cosine of the angular phase difference ? between the current and the voltage.

(4-38)

NOTE: The portion of the active power that is expended in a magnetic core is the total core loss P c .

Aging, Magnetic. The change in the magnetic properties of a material resulting from metallurgical change. This term applies whether the change results from a continued normal or a specified accelerated aging condition.

NOTE: This term implies a deterioration of the magnetic properties of magnetic materials for electronic and electrical applications, unless otherwise specified.

Ampere-turn. Unit of magnetomotive force in the rationalized mksa system. One ampere-turn equals 4 ?/10, or 1.257 gilberts.

Ampere-turn per Meter. Unit of magnetizing force (magnetic field strength) in the rationalized mksa system. One ampere-turn per meter...

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Magnetic Field Sensors
Magnetic field sensors measure magnetic field strength, direction, and/or magnetic flux. They are used for scientific measurement, navigation, and industrial applications.
Magnetic Field Instruments
Magnetic field instruments include meters, gauges, recorders and other instrumentation for the measurement of magnetic fields and/or magnetic flux.
Magnetizers
Magnetizers are used to magnetize parts and charge magnets.
Eddy Current Instruments
Eddy current instruments are NDT instruments that induce detectable eddy currents in conductive materials. They are used to detect flaws, determine thickness, inspect welds, measure conductivity, and sort alloys.
Magnetic Speed Sensors
Magnetic speed sensors rely on a magnet as the sensing element or sensed target to capture rotational or linear speed. They are typically used as gear tooth speed sensors or incorporated into stroboscopes or tachometers.
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