Directional Intermittent Ground-Fault Protection
Overview of Functions
The function Directional intermittent ground-fault protection:
•
Detects the intermittent ground faults in grounded, compensated, or isolated cable systems selectively
•
Can be operated in 2 different modes:
– Operate only by counting directional ground-current pulses
– Operate by integration of the fault current in combination with a directional criterion by counting
directional ground-current pulses
The intermittent ground faults in cable systems are frequently caused by weak insulation or water ingress in
cable joints. The ground faults are characterized by the following properties:
•
Intermittent ground faults show very short high ground-current pulses (up to several hundred amperes)
with a duration of less than 1 ms.
•
Intermittent ground faults are self-extinguishing and reignite within one half period up to several
periods, depending on the power-system conditions and the fault type.
•
Intermittent ground faults can persist over longer periods (several seconds to minutes) and develop to
static ground faults.
Structure of the Function
The function Directional intermittent ground-fault protection can be used in protection function groups
with current and voltage measurement. The function is preconfigured by the manufacturer with 1 stage, and
a maximum of 2 stages can be operated simultaneously.
[DwStrDirIGFP_20140618, 1, en_US]
Figure 6-114 Structure/Embedding of the Function
6.14
6.14.1
6.14.2
Protection and Automation Functions
6.14 Directional Intermittent Ground-Fault Protection
SIPROTEC 5, Overcurrent Protection, Manual 551
C53000-G5040-C017-8, Edition 07.2017
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