The Type of reset curve setting does not apply to 50N-3, 50G-3 or when
the DT operation is selected. The reset is purely defined by the Reset delay
time setting.
4.2.1.7 Application
51N, 51G, 50N, 50G, 50N-3, 50G-3 is designed for protection and clearance of ground
faults in distribution and sub-transmission networks where the neutral point is isolated or
grounded via a resonance coil or through low resistance. It also applies to solidly grounded
networks and ground-fault protection of different equipment connected to the power
systems, such as shunt capacitor bank or shunt reactors and for backup ground-fault
protection of power transformers.
Many applications require several steps using different current pickup levels and time
delays. 51N, 51G, 50N, 50G, 50N-3, 50G-3 consists of three different protection stages:
• Low 51N, 51G
• High 50N, 50G
• Instantaneous 50N-3, 50G-3
51N, 51G contains several types of time-delay characteristics. 50N, 50G and 50N-3,
50G-3 are used for fast clearance of serious ground faults.
4.2.1.8 Signals
Table 321: 51N,51G Input signals
Name
Type Default Description
IG SIGNAL 0 Ground current
BLOCK BOOLEAN 0=False Block signal for activating the blocking mode
ENA_MULT BOOLEAN 0=False Enable signal for current multiplier
Table 322: 50N,50G Input signals
Name
Type Default Description
IG SIGNAL 0 Ground current
BLOCK BOOLEAN 0=False Block signal for activating the blocking mode
ENA_MULT BOOLEAN 0=False Enable signal for current multiplier
1MAC059074-MB A Section 4
Protection functions
615 series ANSI 319
Technical Manual
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