Air gap (magnetic)
eddy currents (each E and I plate is insulated), but the magnetic flux
(red) is able to pass through the remaining "bridges".Air gap in
magnetic material.[1]
In stationary devices, like inductors and transformers, the air gap is used for a few purposes:
- to minimize the
- counter-intuitively, if a DC magnetization is present in an inductor, an increased (up to some limit) air gap actually incrementally increases the effective inductance;[3]
- in a shunt reactor an air gap is used for two reasons:[4]
- with an ungapped core the reactive power is obtained with the disproportionate effect of the iron loss;
- an increase of the gap reduces the ratio of the total loss to the reactive power, with the limiting factor being the increased heating due to the copper loss.
- with an ungapped core the
The total gap is frequently made of a series of small gaps to limit the effect of eddy currents in the core.[5]
When one of the circuit-forming parts of the machine is moving in respect to another (for example, the
synchronous generator is associated with higher short circuit ratio, an often desirable trait.[6]
References
- ^ a b c Considine & Considine 2013, p. 67.
- ^ Calvert 2001.
- ^ Terman 1955, p. 14.
- ^ Brooks 1931, pp. 320–321.
- ^ Pansini 1999, p. 312.
- ^ Boldea 2018, p. 314.
Sources
- Considine, D.M.; Considine, G.D. (2013). "Air gap". Van Nostrand’s Scientific Encyclopedia. Springer US. ISBN 978-1-4757-6918-0. Retrieved 2023-07-10.
- Boldea, I. (2018). Electric Generators Handbook - Two Volume Set. CRC Press. ISBN 978-1-4987-2351-0. Retrieved 2023-07-10.
- Terman, F.E. (1955). Electronic and Radio Engineering. Electronics engineering series. McGraw-Hill. ISBN 978-0-07-063510-4. Retrieved 2023-07-10.
- Calvert, James (2001). "Inside Transformers". University of Denver. Archived from the original on May 9, 2007. Retrieved May 19, 2007.
- Pansini, A.J. (1999). Electrical Transformers and Power Equipment. Fairmont Press. ISBN 978-0-88173-311-2. Retrieved 2023-07-10.
- Brooks, H. B. (1931). "Design of Standards of Inductance, and the Proposed Use of Model Reactors in the Design of Air-Core and Iron-Core Reactors". Journal of Research of the National Bureau of Standards. Vol. 7. U.S. Government Printing Office. pp. 290–328. Retrieved 2023-07-10.
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