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Magnetic signal:
The impulse current flowing into the cable while SSG operation for pin pointing creates a
magnetic field around the cable. This magnetic signal is used to start the propagation time
measurement. In case of weak breakdown noise or strong ambient noises the magnetic
signal can help to evaluate the acoustic signal better.
The unit:
- shows if the Surge Voltage Generator is working properly
- determines the moment when a breakdown noise is to be expected
-
indicates, via the signal intensity, if you are going in direction to or from the cable
route.
Propagation Time Measurement:
With the propagation time measurement the time difference between receipt of the magnetic
and the acoustic impulse is evaluated. Above the fault location the time difference is at
minimum. Carry out 2 to 3 measurements with the UL 30 unit at each measuring point with
the same setting. The results should not show too much deviation. Then you can be sure that
the measurement is correct and no faulty triggering has occurred due to ambient noises.
The time measurement is started by the magnetic impulse and will be stopped by the
acoustic signal. To get save results the UL 30 only takes the measurement as good, if the
two signals are in a defined time frame and the acoustic signal is clearly identified. (clearly
identification of acoustic signal if it is higher than the ambient noises).
In case of non clear identification the display is showing # # # #. Through increase of
acoustic gain it could be possible to get valid measurement. Also the filter adjustment could
help to reduce the influence of ambient noises.
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