
Date Code 20011205
Loss-of-Potential, CCVT Transient Detection,
4-3
Load-Encroachment, and Directional Element Logic
SEL-311A Instruction Manual
Consider using CCVT transient detection logic when you have either of the following conditions:
·
CCVTs with active ferroresonance-suppression circuits (AFSC)
·
The possibility of a source-to-line impedance ratio (SIR) greater than 5
CCVT transients may be aggravated when you have:
·
A CCVT secondary with a mostly inductive burden
·
A low C-value CCVT as defined by the manufacturer
For a description of CCVT transients and transient detection, see the following technical paper
available on the SEL website or FaxBack system:
Capacitive Voltage Transformer: Transient
Overreach Concerns and Solutions for Distance Relaying
.
0
1.5
DWG: M311A015a
CVTBL
SIR > 5 During Zone 1 Fault
ECCVT = Y
SOTFE
3PO
Distance Calculation Stable
2
1
From Figure 5.3
To Figure 3.4 and Figure 3.6
Figure 4.2: CCVT Transient Blocking Logic
L
OAD
-E
NCROACHMENT
L
OGIC
The load-encroachment logic (see Figure 4.3) and settings are enabled/disabled with setting
ELOAD (= Y or N).
The load-encroachment feature allows distance and phase overcurrent elements to be set
independent of load levels. Relay Word bit ZLOAD is used to block the positive-sequence,
voltage-polarized directional element (see Figure 4.15), which may assert for three-phase load.
The distance elements, M1P and M2P, will not operate without directional control. Set !ZLOAD
in the phase overcurrent torque control equation to block phase overcurrent operation.
Содержание SEL-311A
Страница 6: ......
Страница 8: ......
Страница 10: ......
Страница 24: ......
Страница 40: ......
Страница 66: ......
Страница 96: ......
Страница 98: ......
Страница 112: ......
Страница 114: ......
Страница 122: ......
Страница 170: ......
Страница 202: ......
Страница 204: ......
Страница 246: ......
Страница 248: ......
Страница 286: ......
Страница 290: ......
Страница 304: ......
Страница 306: ......
Страница 334: ......
Страница 384: ......
Страница 386: ......
Страница 394: ......
Страница 398: ......
Страница 402: ......
Страница 404: ......
Страница 410: ......
Страница 412: ......
Страница 426: ......
Страница 444: ......
Страница 460: ......
Страница 474: ......