BE1-951
Reporting and Alarm Functions
6-23
The LCD scrolls between the targets and the fault current magnitudes that were recorded during the fault.
Pressing the HMI Reset key will clear these targets and the Trip LED. Password access isn’t required to
reset targets at the HMI.
The RG-TARG (report general-targets) command is used to read and reset targets through the
communication ports.
RG-TARG Command
Purpose:
Read or reset target status.
Syntax:
RG-TARG[=0]
Comments:
Entering RG-TARG returns the target information logged during the most recent trip event.
Entering RG-TARG=0 clears the latched target data.
RG-TARG Command Example
1.
Read the targets.
>RG-TARG
50AN; 150AN
Distance to Fault
The BE1-951 calculates distance to fault each time a fault record is triggered. Refer to the fault record
triggering logic command SG-TRIGGER for triggering details. Distance to fault is calculated and displayed
based on the power line parameters entered with the SG-LINE command. This command describes the
power line parameters for which distance is to be computed over. The parameters should be entered in
units per line length with line length being the actual length of the power line. Line length is entered a unit
less quantity and therefore can be entered in kilometers or miles. The distance results would therefore be
in whatever units the line length represented.
SG-LINE Command
Purpose:
Read/Set System Line parameters
Syntax :
SG-LINE[=<Z1>,<A1>,<Z0>,<A0>,<LL>]
Comments: Z1,Z0=impedance; A1,A0=angle; LL=length
SG-LINE Command Example
1.
Enter data for a power line with the following parameters:
Positive Sequence Impedance = 0.47
S
60°
6
/KM
Negative Sequence Impedance = 1.59
S
70°
6
/KM
Line length = 10KM
The data should be entered as the total impedance of the 10KM power line therefore the data would be
enter as:
>SG-LINE = 4.7, 60, 15.9, 70, 10
Note that both Z1-MAG, and Z0-MAG were scaled by 10 times to represent the entire length of the power
line. Since the units are in KM, the distance results would also be in KM.
Distance calculations are preformed post fault using vector data captured during the actual fault. Pre-fault
current vectors are captured three cycles prior to pickup. Fault voltage and current vectors are captured two
cycles after the trip command is issued. The two cycle wait time allows line transients to settle to provide
more accurate results.
To perform the actual distance calculation, the 951 first must determine the faulted phase. Faults can be
categorized depending on the lines faulted. The various categories are LLL, LL, LLG, or LG, where L=Line
and G=Ground.
To determine the faulted phase, the fault vectors are compensated for load flow using the pre-fault data.
Next the compensated vectors are run though a series sequence component comparisons. Once the faulted
phase is determined, the fault data along with the line parameters are applied using the Takagi algorithm
to determine the impedance of the faulted line. The impedance is divided by the impedance per unit length
to determine the distance to fault. This method assumes the line is homogenous, that the line parameters
