Milwaukee HEAVY DUTY M12 PL, Оригинальное руководство пользователя, Страница: 20 / 589

19 ENGLISH
8 PASSIVE LOCATING - POWER & RADIO
8.1 What is passive locating?
Passive locating refers to the process of detecting signals that „naturally“ occur on pipes and cables. These tend
to fall into two categories, radio signals, and power signals.
Sources of passive locate signals:
Power signals
These signals are 50/60Hz signals created by power transmission cables. When electrical power is distributed
throughout the network, some of the power
fi nds its way back to the power station via the ground. These stray
currents can jump onto pipes and cables and also create power signals. Note that there has to be electrical
current
fl owing to create a detectable signal. For instance, a live cable that is not in use may not radiate a
detectable signal. Also, a very well balanced cable, i.e., the same amount of current fl owing in live and neutral,
will cancel out and may not create a signal. In practice, this is unusual as there are usually enough imbalances in
the cable to create a good detectable signal.
Radio signals
These signals created by low-frequency radio transmitters that are used for broadcasting and communications.
When the signals cross a long conductor such as a pipe or cable, the signals are re-radiated. It is these
re-radiated signals that can be detected by the RF mode.
8.2 Locating power or radio signals
1. Switch on the PIPELINE LOCATOR and use the button to enter the PASSIVE OR RF mode.
2. Hold the PIPELINE LOCATOR vertically and away from likely positions of cables or pipes.
3. Adjust the sensitivity using the buttons so that the bar graph reading is just starting to show some
movement. Note that the line direction indicator feature is not available for the Power or Radio modes.
NOTE
Note that there will be no sound from the speaker until the meter reading is above approximately 10% of full
scale.
PASSIVE