4-8
Protection and Control
BE1-951
7 9 R T D
7 9 R T D
7 9 R T D
7 9 R T D
7 9 R T D
R E S E T
7 9 1 T D
7 9 2 T D
7 9 3 T D
7 9 4 T D
L O C K O U T
R E S E T
Manual Close
1
2
3
4
5
1
Closed
BREAKER
STATUS
O p e n
RESET
TIMER
79C
Recloser
STEP
P0002-07
08-18-00
SG0
SG1
SG2
SG3
Figure 4-5. Example 1 Change Group on Recloser Shot
GROUP1 = ,,,,791 will cause the relay to change from setting group 0 to setting group 1 after the first
reclose, but not till the relay senses the breaker has actually closed. This may be best understood by
examining the diagram in the example below.
Example 1:
In most common practices, only two setting groups would be used for emulating circuit recloser in a fuse
saving scheme (a “fast” curve and a “slow” curve). The settings below call for using setting group 0 during
normal operation, setting group 1 after reclose 2 and remain in setting group 1 until the breaker closed from
lockout. The active group would return to group 0 when the recloser went to reset if any of the close
operations prior to lockout was successful. Setting group 2 and 3 are not used (the 51P element is
monitored by settings, but the switch-to threshold and switch-to time delay are zero, so a switch to group
2 or 3 settings never occurs).
SL-GROUP = 1,0,0,0,0,/0
SP-GROUP1 = 0,0,0,0,792
SP-GROUP2 = 0,0,0,0,51P
SP-GROUP3 = 0,0,0,0,51P
Example 2:
This example illustrates an error in setting the automatic group control. As mentioned above, the settings
group changes via SP-GROUP parameter <prot_ele> = 791, 792, 793 or 794 can only raise the setting
group number. For example, the following would change to group 3 after reclose shot 1 and the setting
group would remain in group 3 until RESET is reached or breaker closed from lockout, at which time the
setting group returns to group 0. The relay would never use setting group 1 or 2.
SL-GROUP = 1,0,0,0,0,/0
SP-GROUP1 = 0,0,0,0,793
SP-GROUP2 = 0,0,0,0,792
SP-GROUP3 = 0,0,0,0,791
