observations in the laboratory, field testing and what traditionally represents an accurate
depiction of a non-stationary signal with a time-dependent spectrum.
GUID-61D297F5-783F-4CF2-BD16-18CE537C9E95-ANSI V1 EN
Figure 167:
Validation of HIZ on gravel
GUID-B9AC5923-6A67-431B-A785-171FD132E1A6-ANSI V1 EN
Figure 168:
Validation of HIZ on
concrete
GUID-988539D2-9893-4B16-8CF6-C32E17991628-ANSI V1 EN
Figure 169:
Validation of HIZ on sand
GUID-9F87C93B-BF44-4488-BD97-209FC90B592A-ANSI V1 EN
Figure 170:
Validation of HIZ on grass
5.4.5
Application
Electric power lines experience faults for many reasons. In most cases, electrical faults
manifest in mechanical damage, which must be repaired before returning the line to
service.
Most of the electrical network faults are ground faults. Conventional protection systems
based on overcurrent, impedance or other principles are suitable for detecting relatively
low-impedance faults which have a relatively large fault current.
However, a small percentage of the ground faults have a very large impedance. They are
comparable to load impedance and consequently have very little fault current. These high-
1MRS240050-IB C
Section 5
Protection-related functions
REF615R
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Technical Manual
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