At the time of this reporting, there have been no effective methods of monitoring current in conductors in space without breaking the circuit or making contact with the conductor. In space, reliability rules all designs, and breaking a circuit to insert a sensor to monitor current would reduce reliability of the system. Hall effect sensors provide a noncontact DC measurement technique, but they are relatively expensive and not rugged enough for the space environment.
A sensor was developed that is rugged and capable of monitoring both DC and AC in a conductor without breaking the circuit or contacting the conductor in any way. The device consists of a split magnetic core concentrator, a piece of magnetostrictive material, a strain gauge affixed to the magnetostrictive material, and an electronic circuit connected to the output of the strain gauge.
The design is based on the magnetostrictive material’s ability to induce strain in the presence of a magnetic field. Magnetic field induced by current flowing through a conductor is captured and focused on a piece of magnetostrictive material. The magnetic flux induces a strain in the material proportional to the current flowing in the conductor. The strain gauge converts strain to resistance. An electrical circuit is used to measure and condition the output of the strain gauge, thus giving a representation of the current flowing in the conductor.
This work was done by Ross Bird, Jonathan Zook, William Bradley, and Safakcan Tuncdemir of QorTek, Inc.; and Julie Slaughter and Eric Summers of ETREMA Products, Inc. for Glenn Research Center.
Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steven Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-19166-1.