ETS-Lindgren HI-3627, Руководство пользователя

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ets-lindgren.com Making Measurements 21
5.0 Making Measurements
To begin making field measurements, plug the probe into the meter.
Turn the range switch to the right, increasing the instrument's
sensitivity until an upscale reading on the meter is observed. The
readings will be most accurate when maximum deflection is observed.
When an over range indication does occur, the next larger range
should be selected. It should be noted that the meter movement is
protected against deflection past the top of scale. Therefore, the "Over
Range" LED must be relied on to indicate an over range condition.
It is not necessary to rotate the sensor to obtain a maximum indication
on the meter. The value of flux density is obtained by taking three
orthogonal measurements of the field. In this case, the sensor has
three separate coils oriented in three mutually perpendicular directions
around a fixed point. The resultant flux density is then found by
calculating the root-sum-squared value from the individual RMS
readings for each axis.
For area surveys of ELF fields, the 30 Hz cutoff will be more useful.
When the 5 Hz frequency cutoff is selected, the unit will be sensitive to
movement of the sensor. This is due to the earth's constant magnetic
field (approximately 500 mG). When the sensor is accelerated or
rotated within this constant field, there will be an output from the
sensor at a frequency corresponding to the movement. Consequently,
during such movement, the meter will typically show significant upscale
indications. The 5 Hz frequency cutoff setting is primarily useful for
measurements at fixed coil positions such as near VDTs.