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||Observatory tests of
||Proceedings of the VI th
National Symposium of Magnetic Measurements (October 18-20, 2000, Kielce, Poland), pp.
magnetometers with low drift
||XIV IMECO World Cong-ress.
New measurements-chal- lenges and visions. (1-6 June 1997, Tampere, Finland)
Vol.IVA, Topic 4, pp.121-126
||Experience of observatory
practice with LEMI-004 magnetometers
||Revista Geofisica, N
48, 1998, pp. 31-40
|The sensor 1 (Fig.2) is
fixed in the protective housing 2 using newly developed original cardan suspension 3,
which provides vertical position of Z axis when the protective housing is tilted no more
than by 8 degrees of arc in any direction. Rough initial housing setting has to be checked
using water level 4 on the upper cover 5 of the housing: if the air bulb is in the limits
of free floating, the vertical positioning is guaranteed. The connecting cable has to be
coupled with the connector 6 on the cover 5.
The cardan suspension 3 is developed on the base of four-points
conic joints. A pressure surface hardening technology was used which allowed to create the
suspension with negligible friction in bearings and good mass center positioning. These
joints obligatorily have to be relieved during transportation. That is why the sensor has
two positions: operational and transportation. In the last one the cardan itself is
blocked, relieved and rigidly fixed inside the housing. In order to transfer the sensor in
the operational position it is necessary to turn off the external protective cover 7 on
the cover 5 of the housing 2, to lift slightly the cardan mechanism top 8 and to turn it
clockwise till arresting. For approximate sensor orientation a north pointing arrow 9 is
dashed on the housing cover 5. Exact orientation has to be made as following. Loose
special fixating screw 10 near the cardan top 8 and rotate all suspension mechanism. After
alignment it has to be fixed back using fixating screw 10. Do not forget to put back
protective cover 7!
The microoscillations of the ground during
the operation are always expected, so an oil dampfer can be used. For this open the plug
11 near the arrow 9 and pour in 0.4 - 0.5 l of silicon oil. Finishing operation, pour out
the oil using the plug 12 on the bottom of the sensor housing 2.
The housing 1 is weatherproof but it is
necessary to avoid total immersion into water together with upper cover 5.
MAIN TECHNICAL PARAMETERS
|Range of work cardan