8/3/2019 SSL_Closed Ring NTW
1/24/8 Schneider Electric
Control and monitoringfunctions
Logic discriminationClosed ring network
ApplicationClosed ring network protection may be provided
usingSepam S42, which includes the following functions:
2 units of directional phase (67) and ear th fault (67N)
protection functions:# a unit to detect faults located in the
"line" direction
# a unit to detect faults located in the "busbar" direction
doubled logic discrimination function, with:
# sending of 2 blocking information, according to the
direction of the fault detected
# receipt of 2 blocking information to block the
directional protection relays according to their
detectiondirection.
Block diagram: Sepam S42
M
T11209
MT11208
With the combination of the directional protectionfunctions and
the logic discrimination function, the
faulty section may be isolated with minimum delay bythe tripping
of the circuit breakers on either side of the
fault.
Blocking information are prepared by protectionfunctions 67 and
67N.
Priority is given to protection function 67: whenprotection
functions 67 and 67N detect faults in
opposite directions at the same time, the blockinginformation is
determined by the direction of the fault
detected by protection function 67.
The instantaneous output of protection function 67,activated at
80% of the Is set point, is used to send
blocking information. This avoids uncertainly when thefault
current is close to the Is set point.
time delay settings for
time-based discrimination
(logic)
(logic)
SSL tripping
direction of 67/67N protection functions
direction of blocking signals
8/3/2019 SSL_Closed Ring NTW
2/24/9Schneider Electric
Control and monitoringfunctions
Logic discriminationClosed ring network
Example of closed ring protection function setting:Case of a
closed ring with two substations, each of which comprises two Sepam
S42relays, marked R11, R12 and R21, R22.
MT11210
Starting at one end of the ring, the detection direction of
units 1 and 2 of the
directional protection functions should be alternated between
line and busbar.
Example of setting of the different Sepam with logic
discrimination:
Substation 1
Sepam S42 no. R11 Sepam S42 no. R12
Logic input/output assignment:I13: blocking reception 1
O3: send blocking information BI1O12: send blocking information
BI2
Logic input/output assignment:I13: blocking reception 1I14:
blocking reception 2O3: send blocking information BI1O12: send
blocking information BI2
67, 67N, unit 1:tripping direction = busbar 67, 67N, unit
2:tripping direction = line
67, 67N, unit 1:tripping direction = line 67, 67N, unit
2:tripping direction = busbar
Substation 2
Sepam S42 no. R22 Sepam S42 no. R21
Logic input/output assignment:I13: blocking reception 1I14:
blocking reception 2O3: send blocking information BI1O12: send
blocking information BI2
Logic input/output assignment:I13: blocking reception 1
O3: send blocking information BI1O12: send blocking information
BI2
67, 67N, unit 1:tripping direction = busbar 67, 67N, unit
2:tripping direction = line
67, 67N, unit 1:tripping direction = line 67, 67N, unit
2:tripping direction = busbar
substation 1substation 2
direction of 67/67N protection functions
direction of blocking signals
