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5.1.4 Connect the output of the device to the utility under examination via contact or non-
contact (induction) method (in accordance with the chosen utility locating method). The contact
method is more efficient for “utility locating” but not always convenient and absolutely unsuitable
for cables locating which are “under voltage”
.
NOTE
In the article only classical methods of “contact” and “non-contact” connection are represented
in various circumstances. Special connection options such as “conductor-conductor, “conductor-
armour”, armour-earth”, “parasitic capacity of unconnected multi-conductor cable” and others
used under the specific conditions and only for “flaw detection” are considered in the “utility
locating methods” indicating in the descriptions of the utility locators
.
1) Base method of the “contact” connection to the utility.
The “clips” are used (“output cable” with “alligator” clips) and earth rod.
One clip should be connected to the input of the utility under examination and the second one to
the earth rod (or to the relevant earthing, e.g. standard earthing bus) at maximum distance from
the utility. It is essential to provide close contact with utility and earth.
The opposite end of the utility under examination should be earthed for creating the paths for
earth return of the signal revocable current.
Special option – bare PIPE IN THE GROUND. The
ground contact is possible along the entire length
of the utility and in any segment. The additional
earthing of the pipe is useless.
In this case the resistance between the
connection to the pipe and earthing point (rod or
other standard earthing bus) is extremely low.
“Revocable” current is reduced considerably
the farther the location from the connection point.
Nevertheless owing to the unique (for this type
of devices) “reserve” of the output current (more
than 5A at the load less than 0.8
Ω
) it offers high
probability of the successful utility locating at a
considerable distance from the connection point.
The diminishing of the signal at the distant pipeline sections is offset by the considerable “reserve”
for the manual or automatic adjustment of the sensitivity of receivers made by “TECHNO-AC”.
NOTE
for “non-contact” connection methods («In» / «An» / «clamp»).
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