GE D60 Instruction Manual page 384

5.6 GROUPED ELEMENTS
The function approximates the voltage rise at the far end of the transmission line according to the following relationship:
In the above equation:
• V_1 is the positive-sequence voltage (phasor quantity) in secondary volts measured at the local terminal.
• I_1 is the positive-sequence current (phasor quantity) in secondary amps measured at the local terminal.
• V is the phase VT secondary setting in the case of wye VTs and the phase VT secondary setting dividec by √3 in
nominal
the case of delta VTs.
• Z and Z
C_mag C_ang
• V_1 is the calculated positive-sequence voltage magnitude at the remote terminal.
C
If the magnitude of Z
C
imately equal to the positive-sequence voltage at the remote end of the line. A more accurate setting of Z
the positive-sequence charging current and the voltages at the local and remote line ends resulting from an open breaker
are known. In this case, the desired reach setting would be:
5
The following settings are available.
• COMPENSATED OV Zc MAG: This setting specifies the magnitude of the impedance Z
should be set to half the positive-sequence series impedance of the line. Alternately, if the positive-sequence charging
currents and local and remote voltages are known, then this value can be calculated from equation above.
• COMPENSATED OV Zc ANG: This setting specifies the angle of the impedance Z
• COMPENSATED OV I_1max: This setting specifies the maximum expected positive-sequence line current for which a
remote overvoltage is anticipated.
• COMPENSATED OV STG1 PKP, COMPENSATED OV STG2 PKP, COMPENSATED OV STG3 PKP: These settings
specify the pickup level for each of the three stages. If any stage is set with no intentional time delay, then the pickup
setting should be set 15% above the anticipated steady state overvoltage to prevent an operation during line energiza-
tion. A stage that is not used may be set to its maximum setting value (3.000 pu) to effectively disable it.
• COMPENSATED OV STG1 DELAY, COMPENSATED OV STG2 DELAY, COMPENSATED OV STG3 DELAY: These
settings specify the time delay for each of the three stages in seconds.
The compensated overvoltage scheme logic is shown below.
5-250
Figure 5–127: PHASOR DIAGRAM
V_1 I_1 Z
 
V_1 pu
------------------------------------------------------------------------------ -
=
C
represent an impedance between the local and remote terminals.
is set to one-half the series impedance of the line (R + jX
Z
=
C
D60 Line Distance Protection System
 
j Z
  C_ang
e
–
C_mag
V
nominal
), the compensated voltage will be approx-
L
V V
–
local remote
----------------------------------------
I
ch arg e
5 SETTINGS
(EQ 5.23)
may be made if
C
(EQ 5.24)
in secondary ohms. This
C
in degrees.
C
GE Multilin