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# Electromagnet

IP.com Disclosure Number: IPCOM000093919D
Original Publication Date: 1966-Apr-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 53K

IBM

## Related People

Deeds, DA: AUTHOR [+1]

## Abstract

A change in coil configuration reduces mutual coupling and improves electromagnet response.

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Electromagnet

A change in coil configuration reduces mutual coupling and improves electromagnet response.

The conventional magnet at A. has armature 1 pivotally mounted at 2 for operation by a single coil 3. The latter is mounted on the center leg of E-shaped core 4. Coil 3 has a resistance R that is approximately proportional to the number of turns N. Coil 3 has an inductance L that is approximately proportional to the number of turns squared N/2/. The force of coil 3 is roughly proportional to current times the number of turns, that is, NI in ampere-turns.

The response time of the magnet is dependent on a number of factors, including the time constant of the circuit. If coil 3 is driven by a constant voltage applied to terminals 5 and 6, the current I follows the exponential curve 1 = (E/R) (1 - e/-Rt/L/)

Improved response time is achieved with the coil configuration at B. Coils 7 and 8 are mounted on the outer legs of E-shaped core 9. If each coil 7 and 8 has one-half the number of turns N of coil 3 and the coils are connected in series from terminals 10 and 11, the curve of current I approximates I = (E/R) (1 - e/- Rt/.5L/)

The same force is produced to attract armature 12, but the time constant is only one-half as large as with the configuration at A. This occurs because coils 7 and 8 act as two separate magnets and mutual coupling between coils is reduced to a minimum. Acting as separate magnets with N/2 turns, the inductance of each coil is one-fourth the...