Arnold - Glossary of Terms

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Glossary

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Saturable Reactor
Describes the main element of a magnetic amplifier used to control electrical power such as for electrical resistance element heating of furnaces.

Saturation
Exists when an increase in magnetizing force, H, does not cause a corresponding increase in the intrinsic magnetic induction, B, of the material.

Saturation Flux Density
The flux density at which a material saturates.

Search Coil
A coil conductor, usually of known area and number of turns, that is used with a fluxmeter to measure the change of flux linkage with the coil.

Secondary Winding
The winding in a transformer that supplies the load with electrical energy which has been converted from the induced magnetic energy in the core.

Self-Inductance
Same as inductance.

Sendust
A 9% silicon, 6% Aluminum, 85% iron alloy in particulate form. The particles are coated with a dielectric film, compacted and cured to form magnetic parts such as inductor cores.

Shielding
Thin-gauge sheet material used to protect sensitive devices from radiated EMI (electromagnetic interference).

Sintered Iron
Powdered iron that has been pressed and sintered into a structural form. This type of material occasionally is used in a magnetic application, but they normally exhibit excessive core losses.

Skewing Of The Loop
When air gap is added to the magnetic path, the hysteresis loop is made to lean over (permeability is reduced); it is said to be skewed or sheared.

Slug Core
A core shaped like a rod, with the winding put around the diameter. Needless to say, leakage flux is a problem.

Soft Magnetic Material
Shaped piece of ferromagnetic material that once having been magnetized is very easily demagnetized, i.e. requires a slight coercive force to remove the resultant magnetism. Generally accepted as having a coercivity of less than 300 oersteds (24 kA/m) though most soft materials used in inductors have coercivities of under 10 oersteds.

Solenoid
A solenoid is an electrically energized coil, the turns of whose winding are insulated from each other even when the conductor is bare and the turns are spaced in air. Two solenoids mutually attract or repel one another according to their relative polarities.

Space Factor
Space factor of a coil is the ratio of the space occupied by the conductor to the total volume of the coil or winding.

Sponge Iron
This is a low-cost powdered iron used to make high-permeability powdered iron cores. This same material also is widely used in the sintered powdered-metal industry.

Square Loop
Refers to a hysteresis loop where the difference between B_m and B_r of a material is quite small, resulting in a rectangular appearance of the intrinsic curve.

Square Wave
An excitation that consists in an abrupt off-on cycling of the voltage. This typically goes in both the positive and negative direction. A positive-only square wave would be typical of pulse excitation.

Stabilization
A treatment of a magnetic material designed to increase the permanency (stability) of its magnetic properties or condition in an application by causing the loss prior to or during installation or assembly, but prior to testing and use.

Stacking Core Tube
A non-magnetic cylinder used to stack sections of conducting material onto. This will also act as the I.D. of the entire solenoid assembly.

Strain Sensitive
Refers to the fact that the properties of magnetic materials can change if the part is subjected to a physical stress.

Swinging Inductors
A special type of inductor that exhibits high inductance at low MMF and moderate inductance at high MMF. There are two popular techniques for accomplishing this: putting a common winding on a high-permeability and a low-permeability core, and putting a staggered gap into a high-permeability core.

Switch Mode Power Supply
A power conversion technique that involves breaking the input power into pulses at a high frequency (by switching it on and off) and re-combining (filtering) these pulses at the output stage. This facilitates easy regulation because the amount of time (the amount of volt-seconds of energy) that the voltage is turned on can be controlled electronically. Generally the output power is monitored and the time of the switch is adjusted in response to the load. On switch mode power supplies with multiple outputs, control still is based on the activity of one of the outputs. But secondary regulation techniques are used on the unregulated" outputs (See mag amp). Abbreviation is SMPS.

Switch Time
A parameter measured on bobbin cores as part of the special pulse test they receive. It is a direct indication of magnetic permeability and core loss.