A liquid switch which does not depend on any mechanical, gravitational, or inertial actuation is developed for use in space environments. It may be remotely operated on low dc voltage

Moore, E. T.

English

NASA Technical Reports Server

Magnetic Pole! 
Magnetic Field
May 1964
NASA TECH BRIEF
Brief 63-10599 
This NASA Tech Brief is issued by the Technology Utilization Division to acquaint industry 
with the technical content of an innovation derived from the NASA space program. 
Liquid Switch Is Remotely Operated by Low DC Voltage 
SWITCH OPEN	 SWITCH CLOSED 
The problem: Reliable switches that can be re-
motely operated by an electric current are needed for 
difficult environments, such as those encountered by 
spacecraft. Ideally, such a switch must operate at low 
DC voltage levels and be capable of high operational 
reliability. Mechanical or electronic switches pres-
ently available do not satisfactorily meet all of these 
requirements. 
The solution: A liquid switch containing no mov-
ing parts that operates on the "left-hand rule" prin-
ciple of electromagnetic force. 
How it's done: A small, closed chamber is partly 
filled with a conducting liquid, such as mercury. Per-
manent magnetic poles are placed in opposite sides 
of the chamber. When a direct current through the 
liquid perpendicular to the applied magnetic field is 
alternated, the resultant electromagnetic force will 
cause the fluid to move toward or away from the 
electrical contacts mounted at one end of the cham-
ber. Current flowing in one direction will cause the
liquid to bridge the contacts and close the switch. 
Reversing the current flow opens the switch. 
Operation of this switch does not depend on any 
mechanical, gravitational, or inertial actuation of the 
mercury, the chamber, or the other parts of the unit. 
The switch is operated from an "On" to "Off' con-
dition and vice versa by an electric current. 
Notes: 
1. With suitable contact arrangements and chamber 
geometry, a switch of this type may be made to 
operate at high cyclic rates. It will then function in 
a manner compatible with either an AC or DC con-
verter, and is suitable for other low voltage applica-
tions. 
As a significant development in actuating switches, 
this invention may be of interest to industry. A nor-
mal amount of development work should cover ap-
plications where it would be an improvement over 
some of the mechanical switches that are currently 
used for remote control purposes.
(continued overleal) 
NOW
This document was prepared under the s ponsorshi p of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment. nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not in'ringe privately-owned 
rights or B. Assumes an y liabilities with respect to the use of, or for 
dama g es resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19630000121 2020-03-11T16:48:08+00:00Z
Patent status: NASA encourages the immediate 
commercial use of this invention. It is owned by 
NASA and inquiries about obtaining royalty-free 
rights for its commercial use may be made to NASA 
Headquarters, Washington, D.C. 20546. 
Source: Duke University
under contract to Goddard Space Flight Center
(GSFC-1 19) 
Brief 63-10599


Liquid switch is remotely operated by low dc voltage

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