Generator Parameters - GE Multilin 489 Instruction Manual

CHAPTER 5: SETPOINTS
Note
5.3.3

Generator Parameters

GENERATOR
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
The setpoint is seen only if
NEUTRAL VT RATIO
"Yes".
The voltage transformer connections and turns ratio are entered here. The VT should be
selected such that the secondary phase-phase voltage of the VTs is between 70.0 and
135.0 V when the primary is at generator rated voltage.
The Neutral VT ratio must be entered here for voltage measurement across the neutral
grounding device. Note that the neutral VT input is not intended to be used at continuous
voltages greater than 240 V. If the voltage across the neutral input is less than 240 V during
fault conditions, an auxiliary voltage transformer is not required. If this is not the case, use
an auxiliary VT to drop the fault voltage below 240 V. The
be the total effective ratio of the grounding transformer and any auxiliary step up or step
down VT.
For example, if the distribution transformer ratio is 13200:480 and the auxiliary VT ratio is
600:120, the
NEUTRAL VT RATIO
Distribution Transformer Ratio
NEUTRAL VT RATIO =
13200
---------------
=
480
Therefore, set
NEUTRAL VT RATIO
PATH: SETPOINTS S2 SYSTEM SETUP
GENERATOR RATED
[ ] MVA: ----------------
GENERATOR RATED
MESSAGE
POWER FACTOR: -------
GENERATOR VOLTAGE
MESSAGE
PHASE-PHASE: --------
GENERATOR NOMINAL
MESSAGE
FREQUENCY: ----------
GENERATOR PHASE
MESSAGE
SEQUENCE: -----------
As a safeguard, when a unit is received from the factory, the
Generator Parameters setpoints will be defaulted to "--------", indicating they are not
programmed. The 489 indicates that it was never programmed. Once these values are
entered, the 489 will be in service. All elements associated with power quantities are
programmed in per unit values calculated from the rated MVA and power factor. The
generator full load amps (FLA) is calculated as
Generator FLA
------------------------------------------------------------------------------------------------------------- -
=
All voltage protection features that require a level setpoint are programmed in per unit of
the rated generator phase-phase voltage.The nominal system frequency must be entered
here. This setpoint allows the 489 to determine the internal sampling rate for maximum
accuracy. If the sequence of phase rotation for a given system is ACB rather than the
NEUTRAL VOLTAGE TRANSFORMER
NEUTRAL VT RATIO
setpoint is calculated as:
×
Auxiliary VT Ratio
600
× -------- - : 1 137.50 : 1
=
120
to 137.50:1
GENERATOR PARAMETERS
Range: 0.050 to 2000.000 MVA or Not
Range: 0.05 to 0.99 or Not
Range: 100 to 30000 V in steps of 1
Range: 25 Hz, 50 Hz, 60 Hz, or
Range: ABC, ACB, or Not Programmed
Generator Rated MVA
3 × Generator Rated Phase-Phase Voltage
setpoint is
entered must
: 1
(EQ 0.1)
Programmed
Programmed
or Not Programmed
Not Programmed
and
PHASE CT PRIMARY
(EQ 0.2)
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