Neutral Current - GE Multilin G650 Manual

5 SETTINGS
The Neutral directional element is an independent Protection element that provides Block and Operation signals. These
signals can be monitored both through the relay HMI or using EnerVista 650 Setup at "Actual > Status > Protection >

Neutral Current"

67N Block (NEUTRAL DIR BLOCK): It indicates that the element is blocked by digital input or because the Operation
magnitude (In current), or the Polarization magnitude (Vn voltage and/or Ip current) level is too low.
67N Operation (NEUTRAL DIR OP): It indicates that the directional element is giving permission, that the angle relations
between the operation magnitude and the polarization magnitude are met, according to the set conditions, or in case of
having selected Permission in the Block Logic setting, it indicates that the element allows operation under block conditions.
Table 5–45: SIGNALS FOR THE NEUTRAL DIRECTIONAL ELEMENT
a) VOLTAGE POLARIZATION OPERATION PRINCIPLES:
Operation Magnitude:
Polarization Magnitude:
shows the operation of the zero sequence polarization, 3V
3V can be calculated from the three phase voltage values, or measured through the fourth voltage input (VN). The
0
operation magnitude I , is calculated from the phase currents.
n
When Ip Polarization is selected, the Polarization magnitude is Ip, this current value measured at the fifth current input
(terminals B11-B12). This polarization current must usually come from a CT measuring the current that flows from the
ground to the neutral of the neutral fault current source, which will mainly be a transformer. The direction is considered to
be Forward when the neutral current I
direction will be Reverse. If the polarization current is lower than 5 mA, the element output takes the value of the Block
Logic setting.VOLTAGE POLARIZATION
GEK-113285A
NEUTRAL DIRECTIONAL
NEUTRAL DIR1 BLOCK
NEUTRAL DIR1 OP
NEUTRAL DIR2 BLOCK
NEUTRAL DIR2 OP
NEUTRAL DIR3 BLOCK
NEUTRAL DIR3 OP
In = 3·Io, calculated from the phase currents.
-3V . Calculated from the phase voltages (if the Auxiliary Voltage setting in General settings
0
main menu is set as VX or VG) or measured at the input terminals (A11, A12)if the Auxiliary
Voltage setting in General settings main menu is set as VN.The relay measures 3V
rotates 180º internally to obtain -3V
is inside a ±90º arc at both sides of the polarization current. In any other case, the
n
G650 Generator Protection & Control System
.
0
, in case of an AG fault. In this case, the polarization magnitude
0
5.4 PROTECTION ELEMENTS
0
5
and
5-49