### Triaxial Fluxgate Magnetometer Tri-Mag 225C25X 0505/1515 and Tri-Mag 225C25Z 0505/1515

- Non-magnetic hermetic seal packaging for fluxgate circuit
- Electronic and fluxgate are integrated in one non-magnetic packaging
- Advanced SOI electronics wafer successfully achieving -60℃ to 225℃
- Internal temperature sensor for thermal modeling from -50℃ to 200℃
- Three orthogonal measurement coils together with one permeable core
- Three components to be measured simultaneously at one point in space
- Installed along the X-axis or Z-axis direction, suitable for MWD and LWD

Electrical wiring diagram

**Applications**

Downhole Directional Sensor Module

These voltage pulses from each measurement coil have been sampled and integrated in the circuit, accordance to the integration voltage the circuit supply feedback currents respectively to each of the measurement coils, which produce magnetic field completely offset the magnetic field ,as the result, the magnetic field in the inner of three measurement coils is zero. The triaxial fluxgate is closed-loop measuring, each of three feedback currents is exactly equal to each of three axis magnetic field components.

The TRI-MAG225C25X allows the three magnetic field components simultaneously to be measured at the same point in space. Non-magnetic hermetic seal packaging is studied, and three sensitive axies and related circuits are integrated into one housing, and directly output three voltages. The TRI-MAG225C25X adapted SOI (Silicon On Insulator) electronics wafer, hybrid circuit technology and hermetic seal packaging. The TRI-MAG225C25X is able to work in wide temperature range (-50℃ to +200℃) and to survive over 2000 hours.

**Calibration coefficient after thermal modeling**

The temperature range of thermal modeling is -50℃ to +200℃, the axis alignment is thermal modeled by zero order polynomial, the bias and scale factor are thermal modeled by third order polynomial. each unit will be calibrated before shipping and build up its own calibration coefficients file. To get the accurate X, Y, Z axis component the triaxial fluxgate output voltage shall be calculated with the calibration coefficient.

The accurate magnetic field is obtained with output voltage and calibration coefficient according to following formulas:

where FXUM, FYUM, FZUM are output voltages of the triaxial fluxgate, the unit is V. T is the current temperature calculated with the output voltage of the thermal sensor in the fluxgate circuit, the unit is ℃, and HX, HY, HZ are the three components of magnetic field, the unit is Gauss.