ABB RELION 620 Series Technical Manual page 554

Section 5
Protection-related functions
5.4.6
5.4.7
Table 402: HIZ Group settings
Parameter Values (Range)
Security level 1...10
Table 403: HIZ Non group settings
Parameter Values (Range)
Operation 1=Enable
5=Disable
System type 1=Grounded
2=Ungrounded
548
impedance faults do not pose imminent danger to power system equipment. However,
they are a considerable threat to people and property. The IEEE Power System Relay
Committee working group on High Impedance Fault Detection Technology defines High
Impedance Faults as those that 'do not produce enough fault current to be detectable by
conventional overcurrent relays or fuses.
High-impedance fault (HIZ) detection requires a different approach than that for
conventional low-impedance faults. Reliable detection of HIZ provides safety to humans
and animals. HIZ detection can also prevent fire and minimize property damage. ABB has
developed innovative technology for high-impedance fault detection with over seven
years of research resulting in many successful field tests.
Signals
Table 400: HIZ Input signals
Name Type
IG SIGNAL
BLOCK BOOLEAN
Table 401: HIZ Output signals
Name Type
TRIP BOOLEAN
Settings
Unit Step
1
Unit Step
Default Description
0 Line residual current measured using SEF CT or phase
CT
0=False Block signal for activating the blocking mode
Description
Trip
Default Description
5 Security Level
Default Description
5=Disable Operation Disable / Enable
1=Grounded System Type
1MAC504801-IB E
620 series ANSI
Technical Manual