Hi Ed At our laboratory we do some tests according to IEC 60945 (equipment for ships) and one of the test are a Compass Safe Distance Test. IEC 60945 specifies a deviation angle of 5.4 degrees when the horizontal field is only 1 micro Tesla (close to the poles of the earth).
The deviation in compass direction depends of the place of test on the earth. In Denmark the vertical field is 46 micro Tesla and the horizontal field is 17 micro Tesla so this deviation angle becomes only 0.3 degrees in Denmark. We do such test by placing a sensitive one direction magnetometer on a wooden table and fix it in the east-west direction at zero field deflection. Then we move the test object towards the sensor and look at the deflection in field. (Remove the keys from your pockets before doing this test. Any moving iron parts nearby disturbs the test). IEC 60945 do also specify a way of magnetizing a test object. It says: 80 A/m DC + 1430 A/m AC, 50Hz. The AC-field provides a stabilization of the field. When you expose some steel to 80 A/m DC only, you get almost no remanent magnetisation. When you add the AC field and then remove the field (as when you demagnetize something) then you get a remanent field from the test object with some steel in it. Hopefully you can use some of this information. Best regards Viggo Brøndegaard DELTA Electronics testing >>> "Price, Ed" <[email protected]> 30-09-99 18.49 >>> Hi Listmembers: Today's weird science question is about sensing the strength of a permanent magnetic field. I need to expose an electronics box to a strong magnetic field (10 Gauss). Then, after removing the field, I need to approach the box with a "compass" and note the separation distance needed to deflect the compass needle a couple of degrees. A couple of degrees is pretty hard to read, even on a large compass! The purpose of the test is to make sure that objects exposed to temporary magnetic fields do not retain enough field to disrupt a nearby magnetic compass. I am trying to determine what kind of sensor I can use. I have been looking at electronic compass modules. Some models provide a DC analog output voltage proportional to angle or heading. Has anyone tried this method? Are the modules stable enough for this to work? Is there a big problem with the placement of the data output lines? Thanks, Ed :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) Ed Price [email protected] Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 (Voice) 619-505-1502 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
