Stator Ground - GE Multilin g60 Instruction Manual

5 SETTINGS
a) MAIN MENU

PATH: SETTINGS GROUPED ELEMENTS
 STATOR
 GROUND
MESSAGE
MESSAGE
MESSAGE
Three means of stator ground fault protection are provided:
• 100% stator ground protection that uses third harmonic signals at the neutral of the machine and in the zero-sequence
voltage of the machine terminals.
• Third harmonic neutral undervoltage protection that responds to the third harmonic in the voltage at the machine neu-
tral point.
• 100% stator ground protection based on sub-harmonic injection.
The three protection elements are configured through their individual setting menus. They share the
setting. This setting specifies a signal source used to provide current and voltage signals for stator ground fault
SOURCE
protection.
For the 100% stator ground protection function, the stator ground source shall be configured as follows:
• Phase voltages measured at the terminal of the machine shall be configured as phase VT banks. The element extracts
the third harmonic of the zero-sequence voltage from the phase voltages in order to operate. The VTs must be con-
nected in wye.
• Voltage measured at the neutral of the machine shall be configured as the auxiliary VT bank. The element extracts the
third harmonic of the auxiliary voltage from the source in order to operate.
For the third harmonic neutral undervoltage protection function, the stator ground source shall be configured as follows:
• Phase voltages measured at the terminal of the machine shall be configured as phase VT banks. The element uses
the voltages to measure the power at the machine terminals for power supervision.
• Phase currents measured at the terminal of the machine shall be configured as phase CT banks. The element uses
the currents to measures the power at the machine terminals for power supervision.
• Voltage measured at the neutral of the machine shall be configured as the auxiliary VT bank. The element extracts the
third harmonic of the auxiliary voltage from the source in order to operate.
For the sub-harmonic injection based 100% stator ground protection, the stator ground source shall be configured as fol-
lows:
• Voltage measured at the neutral of the machine shall be configured as the auxiliary VT bank. The element extracts the
20 Hz component of the auxiliary voltage from the source in order to calculate resistance. The fundamental frequency
component from the same input is extracted when the same source is configured for auxiliary overvoltage protection
element to provide 95% stator ground fault protection. The auxiliary VT connection setting should be chosen as "Vn"
for this element.
• Current measured at the secondary of the neutral grounding transformer of the machine shall be configured as the
sensitive ground CT bank. The element extracts the 20 Hz component of the ground current from the source in order to
calculate resistance.
• This source can be independent of any of the other inputs from the generator such as neutral end CTs, terminal end
CTs and terminal VTs. Or these auxiliary VT and sensitive ground CT can be combined with either neutral side or ter-
minal side inputs within the same source settings.
GE Multilin
 
SETTING GROUP 1(6)

STATOR GROUND

STATOR GROUND
SOURCE: SRC1
 100% STATOR
 GROUND
 3RD HARM NTRL
 UNDERVOLTAGE
 SH STATOR
 GROUND
G60 Generator Protection System
5.6 GROUPED ELEMENTS
5.6.16 STATOR GROUND
Range: SRC 1, SRC 2, SRC 3, SRC 4
See page 5–204.
See page 5–207.
See page 5–209.
STATOR GROUND
5
5-203