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 MIL-HDBK-1023/4
Figure 10
Use of the Acoustic Detector
4.9
Directional Detector
4.9.1
General
a) The directional detector, Figure 11measures the direction and magnitude of short
duration current pulses from capacitor-discharge generators. It is used for locating faults
between conductors or between a conductor and shield in underground power cables.
b) With the selection of two magnetic pickups and one conductive pickup, it can be
used to locate faults in shielded or unshielded cables, either direct-buried or in duct. The
magnetic pickups give a general location of the fault; more accurate location of unshielded
direct-buried cables is possible with the conductive or earth-gradient pickup.
c) The test set is also effective for tracing buried cable, giving a precise fix on both
location and depth. In addition to impulse detecting, the test set can be used for tracing buried
cables energized at frequencies between 60 and 1000 Hz.
locating high-resistance earth faults in direct-buried cables energized at 60 Hz, using earth-
gradient probes.
e) The test set is designed to give optimum response to the typical current impulse
waveform produced in a cable by a capacitor discharge. The test set measures the strength and
direction (polarity) of the magnetic field created by the impulse current. The set not only
indicates the presence or absence of an impulse current in the vicinity, but also its direction and
magnitude. This information is valuable in fault locating.
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