Application; Signals - ABB RELION 620 Series Technical Manual

1MAC504801-IB E
4.1.4.7
4.1.4.8
620 series ANSI
Technical Manual
The Type of reset curve setting does not apply to 50N/G-3 or when the DT
operation is selected. The reset is purely defined by the Reset delay time
setting.

Application

51N/50N or 51G/50G 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/50N or 51G/50G consists of three different protection stages:
• Low 51N/G
• High 50N/G-1/2
• Instantaneous 50N/G-3.
51N/G contains several types of time-delay characteristics. 50N/G-1/2 and 50N/G-3 are
used for fast clearance of serious ground faults.

Signals

Table 137: 51N/G Input signals
Name Type
IN or IG SIGNAL
BLOCK BOOLEAN
ENA_MULT BOOLEAN
Table 138: 50N/G-1/2 Input signals
Name Type
IG or IN SIGNAL
BLOCK BOOLEAN
ENA_MULT BOOLEAN
Default Description
0 Ground current
0=False Block signal for activating the blocking mode
0=False Enable signal for current multiplier
Default Description
0 Ground current
0=False Block signal for activating the blocking mode
0=False Enable signal for current multiplier
Section 4
Protection functions
193