RIDGID SR-60 manual Sonde Locating, Operating Tips for Passive Line Tracing

SeekTech SR-60

Operating Tips for Passive Line Tracing

1.In Passive Locating if you are looking for a known line, be sure you are using the best frequency for the line in question. This may be, for example, 60 Hz (1) for a power line, or it may turn out that 60 Hz (9) produces a more reliable response on a particular line.

2.If seeking a cathode-protected pipe in Passive Mode, use higher-frequency (greater than 4 kHz) to pick up harmonics.

3.Remember that pipes can carry currents that will show up on a Passive Trace as well as cables will; the only guarantee of a locate is exposure and visual inspection.

4.In general, Passive Trace locating is less reliable than Active Line Tracing because Active Line Tracing offers the positive identification of the signal from the transmitter.

5.Especially in Passive Line Tracing, knowing that you have found something is not the same as knowing what you have found. It is essential to use all the indicators available, such as Measured Depth, Signal Strength, etc., to confirm a locate. If it is possible to access part of a passively-located cable, it can then be energized using a transmitter and positively traced.

6.While Passive Line Trace is most often used on 50/60Hz power lines, other cables such as phone lines, CATV lines, etc., can be energized in operation, or by transient radio frequencies in the region and may appear on Passive Line Trace searches.

7.Verify a passive locate by finding a known termination point and hooking up a transmitter to it to do an active locate on the line, if this is possible.

Sonde Locating

The SR-60 can be used to locate the signal of a Sonde (transmitter) in a pipe, so that its location can be identified above ground. Sondes can be placed at a problem point in the pipe using a camera, push rod, or cable. They can also be flushed down the pipe. A Sonde is often used for locating non-conducting pipe and conduit.

Important!

Signal strength is the key factor in determining the Sonde’s location. Take care to maximize the Signal Strength prior to marking an area for excavation.

The following assumes that the Sonde is in a horizontal pipe, the ground is approximately level and the SR-60 is held with the antenna mast vertical.

The field of a Sonde is different in form from the circular field around a long conductor such as a pipe or cable. It is a dipole field like the field around the Earth, with a north Pole and a south Pole.

Figure 33: Earth's Dipole Field

In the Sonde’s field, the SR-60 will detect the points at either end where the field lines curve down toward the vertical, and it will mark these points on the map display with a “Pole” icon (). The SR-60 will also show a line at 90 degrees to the Sonde, centered between the Poles, known as the “Equator”, much like the Equator on a map of the Earth if the planet were viewed sideways (See Figure 33).

Note that because of the SR-60’s Omnidirectional antennas, the signal stays stable regardless of orientation. This means the signal will increase smoothly when approaching the Sonde, and decrease smoothly moving away.

Note: A Pole is found where field lines turn vertical. The Equator occurs when the field lines are horizontal.

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