Schweitzer Engineering Laboratories SEL-700G Series, Инструкция по эксплуатации, Страница: 193 / 824

4.87
Date Code 20170814 Instruction Manual SEL-700G Relay
Protection and Logic Functions
Group Settings (SET Command)
➤
The GENDEDO setting ensures that inadvertent energization
protection remain armed for 1 second after the 27V1X1 element
deasserts to allow for reapplication of the generator field. If you
can parallel the generator within 1 second of reenergizing the
field, shorten the GENDEDO setting.
➤
INADPU must be set less than GENDEDO.
Intertie and Feeder
Protection
This section describes elements associated primarily with intertie protection,
but which may also be applied to generator and feeder protection. Refer to
Table 1.2 for the list of elements included in various relay models.
Overcurrent Elements
Three levels of instantaneous/definite-time elements are available for phase
and two levels of neutral, residual, and negative-sequence overcurrent, as
shown in Table 4.17 through Table 4.20 and in Figure 4.53, Figure 4.54 and
Figure 4.56. Refer to Table 1.2 for the available elements in specific relay
models.
Each element can be torque controlled through the use of appropriate
SEL
OGIC
control equations (for example, when 50PY1TC := IN401, the
50PY1 element operates only if IN401 is asserted). Also, the level 1 and level
2 elements can be controlled by directional elements according to the relay
model number (refer to Table 1.2 and Table 4.34). Directional elements are
described later in this section. Level 3 elements (phase overcurrent) are always
non-directional.
Normally, the phase instantaneous overcurrent elements (50Pm1 through
50Pm3) use the output of the one-cycle cosine-filtered phase current to
operate (see Figure 4.53). During severe CT saturation, a distorted secondary
waveform can substantially reduce the cosine-filtered phase magnitude.
Relying solely on the output of the cosine-filtered secondary current can
jeopardize the operation of the high-set instantaneous overcurrent element. In
the SEL-700G Relay, for any phase instantaneous overcurrent element set
above eight times the relay current input rating (40 A in a 5 A relay), the
overcurrent element also uses the output of a bipolar peak detector when the
Table 4.17 Phase Overcurrent Settings
Setting Prompt Setting Range
Setting Name :=
Factory Default
a
a
m = X or Y.
PHASE IOC LEVEL OFF, 0.50–96.00 A
b
b
Setting ranges shown are for 5 A nominal CT rating. Divide by 5 for 1 A CTs.
50Pm1P := OFF
PHASE IOC DELAY 0.00–400.00 s 50Pm1D := 0.00
PH IOC TRQCTRL SEL
OGIC
50Pm1TC := 1
PHASE IOC LEVEL OFF, 0.50–96.00 A
b
50Pm2P := OFF
PHASE IOC DELAY 0.00–400.00 s 50Pm2D := 0.00
PH IOC TRQCTRL SEL
OGIC
50Pm2TC := 1
PHASE IOC LEVEL OFF, 0.50–96.00 A
b
50Pm3P := OFF
PHASE IOC DELAY 0.00–400.00 s 50Pm3D := 0.00
PH IOC TRQCTRL SEL
OGIC
50Pm3TC := 1
NOTE:
The cosine filter provides
excellent performance in removing dc
offset and harmonics. However, the
bipolar peak detector has the best
performance in situations of severe
CT saturation when the cosine-filter
magnitude estimation is significantly
degraded. Combining the two
methods provides an elegant solution
for ensuring dependable short-circuit
overcurrent element operation.