Oscillography - GE L90 Instruction Manual

PRODUCT SETUP
If the broken-delta neutral voltage is not available to the relay, an approximation is possible by assuming the missing zero-
sequence voltage to be an inverted voltage drop produced by the zero-sequence current and the user-specified
equivalent zero-sequence system impedance behind the relay: V0 = –Z0 × I0. In order to enable this mode of operation, the
FAULT REPORT 1 VT SUBSTITUTION
The
FAULT REP 1 SYSTEM Z0 MAG
value is "I0". The magnitude is to be entered in secondary ohms. This impedance is an average system equivalent behind
the relay. It can be calculated as zero-sequence Thevenin impedance at the local bus with the protected line/feeder
disconnected. The method is accurate only if this setting matches perfectly the actual system impedance during the fault.
If the system exhibits too much variability, this approach is questionable and the fault location results for single-line-to-
ground faults is trusted accordingly. Keep in mind that grounding points in the vicinity of the installation impact the system
zero-sequence impedance (grounded loads, reactors, zig-zag transformers, shunt capacitor banks, and so on).
For proper operation of the multi-ended fault locator, the nominal primary voltage is expected to appear identical
at all line terminals as seen from the nominal secondary voltage, VT ratio, and VT connection settings of the first
87L source.

5.3.9 Oscillography

5.3.9.1 Menu
SETTINGS  PRODUCT SETUP  OSCILLOGRAPHY
 OSCILLOGRAPHY

5
Oscillography records contain waveforms captured at the sampling rate as well as other relay data at the point of trigger.
Oscillography records are triggered by a programmable FlexLogic operand. Multiple oscillography records can be captured
simultaneously.
When EnerVista UR Setup creates a new settings file, a Smart defaults feature automatically enters a basic oscillography
configuration. The basic configuration changes the factory default values to make the number of samples per cycle 32,
adds a selection of digital and analog channels that are often of interest, and adds a FlexLogic equation to trigger
oscillography. Review and update this basic configuration as required for the application at hand.
The
NUMBER OF RECORDS
other factors, such as sample rate and the number of operational modules. There is a fixed amount of data storage for
oscillography; the more data captured, the less the number of cycles captured per record. See the
RECORDS  OSCILLOGRAPHY
configurations with corresponding cycles/record. The minimum number of oscillographic records is three.
5-116
setting is set to "I0".
and
FAULT REP 1 SYSTEM Z0 ANGLE
NUMBER OF RECORDS:

5
TRIGGER MODE:

Automatic Overwrite
TRIGGER POSITION:

50%
TRIGGER SOURCE:

Off
AC INPUT WAVEFORMS:

16 samples/cycle
 DIGITAL CHANNELS


 ANALOG CHANNELS


is selectable, but the number of cycles captured in a single record varies considerably based on
menu to view the number of cycles captured per record. The following table provides sample
settings are used only when the
Range: 1 to 64 in steps of 1
Range: Automatic Overwrite, Protected
Range: 0 to 100% in steps of 1
Range: FlexLogic operand
Range: Off; 8, 16, 32, 64 samples/cycle
See below
See below
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
setting
VT SUBSTITUTION
ACTUAL VALUES 