F.W. Bell 8000 series, Инструкция по эксплуатации

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F.W. BELL 8000 Series Gauss/Tesla Meter Instruction Manual
Section 6 – Flux Density Measurement 6-25
Sources of
Measurement
Error
When making flux density measurements there are several conditions that
can introduce errors:
1) Failure to zero the error signals from the meter, probe, and nearby
sources of magnetic interference.
2) Subjecting the probe to physical abuse.
3) One of the most common sources of error is the angular position of the
probe with respect to the field being measured. A Hall Effect sensor is
not only sensitive to the number of flux lines passing through it but also
the
angle
at which they pass through it. The Hall Effect sensor produces
the greatest signal when the flux lines are perpendicular to the sensor as
shown below.
Figure 6-19 Probe Output versus Flux Angle
Note: The probe is calibrated and specified with flux lines passing
perpendicularly through the Hall effect sensor with the probe
positioned for a maximum reading in the air gap of a reference
magnet. There may be small angular variations between the Hall
sensor plate and the probe’s external surface.
4) As shown below, the distance between the magnetic source and the Hall
probe increases fewer flux lines will pass through the probe, causing the
probe’s output to decrease.
Figure 6-20 Probe Output versus Distance