GE 489 User Manual

GE Power Management
489 Generator Management Relay 4-27
4 SETPOINT PROGRAMMING 4.6 S5 CURRENT ELEMENTS
4
4.6.9 GROUND DIRECTIONAL
The 489 detects ground directional by using two measurement quantities:
V
0
and I
0
. The angle between these quantities
determines if a ground fault is within the generator or not. This function should be coordinated with the 59GN element (95%
stator ground protection) to ensure proper operation of the element. Particularly, this element should be faster. This ele-
ment must use a core balance CT to derive the
I
0
signal. Polarity is critical in this element. The protection element is
blocked for neutral voltages,
V
0
, below 2.0 V secondary. Refer to the APPLICATION NOTES for more details.
The pickup level for the ground current elements is programmable as a multiple of the CT. The 50:0.025 CT is
intended for very sensitive detection of ground faults and its nominal CT rating for the 489 is 50:0.025.
For example, if the ground CT is 50:0.025, a pickup of 0.20 would be 0.20 x 5 = 1 A primary. If the ground CT is 50:0.025, a
pickup of 0.05 would be 0.05 x 5 = 0.25 A primary. Refer to Appendix B for Application Notes.

GROUND DIRECTIONAL

[ENTER] for more
SUPERVISE WITH
DIGITAL INPUTS: Yes
Range: Yes, No. Seen only if a digital input is assigned to
Ground Switch Status
GROUND DIRECTIONAL
MTA: 0°
Range: 0°, 90°, 180°, 270°
Note: MTA = Maximum Torque Angle
GROUND DIRECTIONAL
ALARM: Off
Range: Off, Latched, Unlatched
ASSIGN ALARM
RELAYS (2-5): ---5
Range: Any combination of Relays 2 to 5
GROUND DIR. ALARM
PICKUP: 0.05 x CT
Range: 0.05 to 20.00
×
CT in steps of 0.01
GROUND DIR. ALARM
DELAY: 3.0 sec.
Range: 0.1 to 120.0 sec. in steps of 0.1
GROUND DIR. ALARM
EVENTS: Off
Range: On, Off
GROUND DIRECTIONAL
TRIP: Off
Range: Off, Latched, Unlatched
ASSIGN TRIP
RELAYS (1-4): 1---
Range: Any combination of Relays 1 to 4
GROUND DIR. TRIP
PICKUP: 0.05 x CT
Range: 0.05 to 20.00
×
CT in steps of 0.01
GROUND DIR. TRIP
DELAY: 3.0 sec.
Range: 0.1 to 120.0 sec. in steps of 0.1
ENTER
ESCAPE
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NOTE

GE 489 Specifications

General

Brand	GE
Model	489
Category	Relays
Language	English