GE G60 Instruction Manual page 404

5.6 GROUPED ELEMENTS
c) THIRD HARMONIC NEUTRAL UNDERVOLTAGE
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PATH: SETTINGS GROUPED ELEMENTS
 3RD HARM NTRL
 UNDERVOLTAGE
5
The third harmonic neutral undervoltage function detects a loss of third harmonic voltage at the generator neutral. The per-
centage of stator winding covered by this function depends on the pickup setting and the amount of third harmonic gener-
ated by the machine at the time of the fault. A settable window of forward power can supervise this element for enhanced
security. The element is also supervised by positive-sequence voltage measured at the generator output terminals. This
element can be used with either wye or delta connected VTs on the terminal side and requires the machine neutral voltage
to be connected via an auxiliary voltage channel of a relay VT bank.
• 3RD HARM NTRL UV PICKUP: This setting specifies the pickup level for the magnitude of the third harmonic of the
neutral voltage. This setting is entered in pu of the nominal auxiliary voltage.
The magnitude of the third harmonic voltage at the neutral point is monitored in the
menu. Measuring the actual value of the operating quantity for a specific machine under variety of
STATOR GROUND
load conditions may be helpful when selecting the pickup threshold for this feature.
• 3RD HARM NTRL UV MAX POWER: This setting specifies the maximum active power that inhibits this protection
function. If the measured power is below this setting but above the
shall not operate. This setting applies to three-phase power and is entered in pu. The base quantity is 3-phase power
on primary side, which is calculated as
delta connected VTs; and 3 x Phase CT Primary x Phase VT Ratio x Phase VT Secondary in case of wye connected
VTs.
For example, a setting of 20% for a 200 MW machine, is 0.20 × 200 MW = 40 MW. If 7.967 kV is a primary VT voltage
and 10 kA is a primary CT current, the source pu quantity is 239 MVA, and thus, the pu power setting is 40 MW /
239 MVA = 0.167 pu.
• 3RD HARM NTRL UV MIN POWER: This setting specifies the minimum active power that inhibits this protection func-
tion. If the measured power is above this setting but below the
not operate. If the
values less than the
This setting applies to three-phase power and is entered in pu. The base quantity is 3 × VT pu base × CT pu base.
5-244
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SETTING GROUP 1(6)
3RD HARM NTRL UV
FUNCTION: Disabled
3RD HARM NTRL UV
MESSAGE
PICKUP: 0.3000 pu
3RD HARM NTRL UV PKP
MESSAGE
DELAY: 0.00 s
3RD HARM NTRL UV MAX
MESSAGE
POWER: 0.200 pu
3RD HARM NTRL UV MIN
MESSAGE
POWER: 0.200 pu
3RD HARM NTRL UV
MESSAGE
VOLT SUPV: 0.500 pu
3RD HARM NTRL UV BLK:
MESSAGE
Off
3RD HARM NTRL UV
MESSAGE
TARGET: Self-reset
3RD HARM NTRL UV
MESSAGE
EVENTS: Disabled
3 x Phase CT Primary x Phase VT Ratio x Phase VT Secondary in case of
3RD HARMONIC NTRL UV MIN POWER
3RD HARM NTRL UV MAX POWER
G60 Generator Protection System
 
STATOR GROUND
Range: Disabled, Enabled
Range: 0.0000 to 3.0000 pu in steps of 0.0001
Range: 0.00 to 600.00 s in steps of 0.01
Range: 0.000 to 30.000 pu in steps of 0.001
Range: 0.000 to 30.000 pu in steps of 0.001
Range: 0.000 to 1.250 pu in steps of 0.001
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
3RD HARM NTRL UV MIN POWER
3RD HARM NTRL UV MAX POWER
is set to "0.00 pu", then the element will not operate for all power
setting.
5 SETTINGS
3RD HARM NTRL UNDERVOLTAGE

ACTUAL VALUES METERING
setting the element
setting the element shall
GE Multilin
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