Instrumentation and Test Expert

Saturable Core Reactor Theory for Automatic Test Equipment (page 4)

III. BASIC SATURABLE REACTOR THEORY
A saturable core reactor is sometimes known as a magnetic amplifier. The component is based on an inductor built on a nonlinear magnetic material core. In addition to the primary inductive winding, at least one additional control winding is built onto the core. A DC current is applied to the control winding and is used to adjust the magnetic properties of the core, specifically the magnetic permeability.

The inductance can be changed by varying any of the four variables on the right side of equation 2. Three of the four variables are physical properties that would require moving parts to modify. The remaining property, the permeability of the material can be used to adjust an inductor’s inductance value without requiring a mechanical system to change properties like dimensions, number of turns, etc.

For a nonlinear magnetic material it is possible to reach a saturation point of the flux density. In this saturated region, the value of the permeability of the material is smaller than in the unsaturated or linear region. An adjustable magnetic field can be applied to the inductor core to change the value of the permeability by saturating the flux density of the core.

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