5.4 High-impedance fault detection PHIZ (ANSI HIZ)
5.4.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
High-impedance fault detection PHIZ HIF HIZ
5.4.2 Function block
Figure 669: Function block
5.4.3 Functionality
A small percentage of earth faults have a very large impedance. They are comparable
to load impedance and consequently have very little fault current. These high-
impedance faults do not pose imminent danger to power system equipment.
However, they are a substantial threat to humans and properties; people can touch
or get close to conductors carrying large amounts of energy.
ABB has developed a patented technology (US Patent 7,069,116 B2 June 27, 2006, US
Patent 7,085,659 B2 August 1, 2006) to detect a high-impedance fault.
The high-impedance fault detection function PHIZ also contains a blocking
functionality. It is possible to block function outputs, if desired.
5.4.4 Analog channel configuration
PHIZ has two analog group inputs which must be properly configured.
Table 1128: Analog inputs
Input Description
I3P Three-phase currents
IRES Residual current (measured or calculated)
See the preprocessing function blocks in this document for the possible
signal sources.
1MRS759142 F Protection related functions
REX640
Technical Manual
1179
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