4 Protection Functions and Specifications
D02706R02.30
L-PRO 4000 User Manual
4-43
Z Circle Trigger
Figure 4.23: Z Circle Trigger
The Impedance Circle Trigger (Z Circle Trigger) triggers the relay to record on
a dynamic swing disturbance — only used to trigger a recording. This trigger
is usually set outside the last protection zone used and blocked during LOP
conditions.
Fault Locator
Whenever a fault occurs and the line trips, the fault locator calculates the fault
type and the distance to the fault. This information is available from the front
display of the relay or through Port 150, 123 or the SCADA port or through
Relay Control Panel software. Fault locator information can also be captured
optionally in event records. Fault locator can be enabled/disabled through set-
tings (system parameters).
The fault locator is initiated by the following logic:
• 21 Trip
• 50N Trip
• 51N Trip
• Scheme Trip
• 21 Alarm (configurable)
The relay fault locator uses the Takagi method of fault location. The imped-
ance calculated for a fault initiated by any of the above functions will be cal-
culated and compared with the line impedance to calculate distance to fault.
Table 4.25: Z Circle Trigger Settings
Z Circle Trigger
Enable/Disable
Positive Sequence Impedance
0.1 to 50.0 ohms secondary (5 A)
0.5 to 250.0 ohms secondary (1 A)
X
Z
R
Summary of Contents for L-PRO 4000
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