GE Multilin 489

5–18 489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
CHAPTER 5: SETPOINTS
5.3 S2 System Setup
5.3.1 Current Sensing
PATH: SETPOINTS ZV S2 SYSTEM SETUP Z CURRENT SENSING
As a safeguard, the PHASE CT PRIMARY and GENERATOR PARAMETERS setpoints are
defaulted to “--------” when shipped, indicating that the 489 was never programmed. Once
these values are entered, the 489 will be in service. Select the Phase CT so that the
maximum fault current does not exceed 20 times the primary rating. When relaying class
CTs are purchased, this precaution helps prevent CT saturation under fault conditions. The
secondary value of 1 or 5 A must be specified when ordering so the proper hardware will
be installed. The
PHASE CT PRIMARY setpoint applies to both the neutral end CTs as well as
the output CTs.
For high resistance grounded systems, sensitive ground current detection is possible if the
50:0.025 Ground CT is used. To use the 50:0.025 CT input, set
GROUND CT to “50:0.025”. No
additional ground CT messages will appear. On solid or low resistance grounded systems,
where fault currents may be quite large, the 489 1 A/5 A secondary Ground CT input should
be used. Select the Ground CT primary so that potential fault current does not exceed 20
times the primary rating. When relaying class CTs are purchased, this precaution will
ensure that the Ground CT does not saturate under fault conditions.
The 489 uses a nominal CT primary rating of 5 A for calculation of pickup levels.
5.3.2 Voltage Sensing
PATH: SETPOINTS Z S2 SYSTEM SETUP ZV VOLTAGE SENSING

CURRENT [Z]
PHASE CT PRIMARY:
-------------
Range: 1 to 5000 in steps of 1, Not
Programmed
MESSAGE
GROUND CT:
50:0.025
Range: None, 1A Secondary, 5A
Secondary, 50:0.025
MESSAGE
GROUND CT RATIO:
100: 1
Range: 10 to 10000 in steps of 1. Seen
only if Ground CT Type is 1 A
MESSAGE
GROUND CT RATIO:
100: 5
Range: 10 to 10000 in steps of 1. Seen
only if Ground CT Type is 5 A

VOLTAGE [Z]
VT CONNECTION TYPE:
None
Range: Open Delta, Wye, None
MESSAGE
VOLTAGE TRANSFORMER
RATIO: 5.00:1
Range: 1.00:1 to 300.00:1 in steps of
0.01
MESSAGE
NEUTRAL VOLTAGE
TRANSFORMER: No
Range: No, Yes
MESSAGE
NEUTRAL VT
RATIO: 5.00:1
Range: 1.00:1 to 240.00:1 in steps of
0.01.
Courtesy of NationalSwitchgear.com