MIGHTY MIGHT

CD 2478084 E&MP15.003

Electric Circuits, Breakers

August 18, 1967

This circuit breaker that resets itself someday may take the place of conventional fuses which are destroyed by overload conditions.

It is under development at the National Aeronautics and Space Administration's Goddard Space Flight Center, Greenbelt, Md.

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TINY CIRCUIT BREAKER HAS UNLIMITED FUTURE

A mighty mite someday may make the home fuse box obsolete.

The tiny device, a circuit breaker that resets itself, is under development at the National Aeronautics and Space Administration's Goddard Space Flight Center here.

In many commercial uses it may someday take the place of conventional fuses which are destroyed by overload conditions.

Composed of a special epoxy resin impregnated with particles of metal, the device will temporarily interrupt a circuit during overload.

The process is completely reversible.

The inventor is Edward F. Thomas Jr. of the Quality Assurance Branch of the Test and Evaluation Division at Goddard.

NASA has a variety of potential fuse problems in its spacecraft development programs, most of which are caught in pre-launch tests.

Conventional circuit breakers provide the protection but could cause an experiment to be lost after even an intermittent overload.

The reversible fuse is one answer and its spacecraft use is now under extensive study.

The key discovery for the new fuse was made by Thomas while a student at Northeastern University in Boston, Mass.

When he heated a resin conductor used in fluorescent fixtures one day he found that the resistance was increased.

When the flame was removed, it returned to normal.

After he received his Bachelor of Science degree in electrical engineering in 1963, Thomas came to Goddard bringing the idea with him.

"Any way you can use a fuse, you can use this, and better," Thomas reports.

The device cannot be damaged mechanically and may be molded into any size or shape.

Theoretically, the fuse action needs only two microscopic bits of metal.

With malleable thermoplastic epoxy, entire wires might be made of fuse material.

According to Thomas, the commercial applications are unlimited.

A fuse might be molded into a screw and imbedded in an automobile engine block replacing the more expensive thermostat-like-device which indicates when the engine is hot.

It might be used in fire alarm systems to trigger alarm bells, indicator lights and sprinklers all at once.

The device was announced by NASA's Office of Technology Utilization as part of the Agency's program to make results of space research available to industry. 

Original Caption by Science Service
^©NASA