ABB 615 Series ANSI, Technical Manual

Page: 407 / 713

Section 5
1MAC050144-MB C
Protection related functions
400 615 series ANSI
Technical Manual
Figure 198: Block diagram of HIZ
HIZ is based on algorithms that use ground current signatures which are considered non
stationary, temporally volatile, and of various burst duration. All harmonic and
non-harmonic components within the available data window can play a vital role in the
high impedance fault detection. A major challenge is to develop a data model that
acknowledges that high impedance faults could take place at any time within the
observation window of the signal and could be delayed randomly and attenuated
substantially. The model is motivated by extensive research, actual experimental
observations in the laboratory, field testing, and what traditionally represents an accurate
depiction of a non stationary signal with a time dependent spectrum.
Figure 199: Validation of HIZ on gravel Figure 200: Validation of HIZ on concrete
Figure 201: Validation of HIZ on sand Figure 202: Validation of HIZ on grass