BE1-51/27R - Installation
4-19
Assuming that the 67 relays will not operate for fault 3, the generators will be unnecessarily tripped if the line
relaying fails to operate or if breaker R fails to interrupt the fault. Redundant line relaying will minimize the need
for generator tripping. Use of a breaker failure timer set at 0.25 seconds would avoid generator tripping for
failure of breaker R to interrupt.
NOTE 1:
194 a @ -31.8
(3700 kVA @
0.87 Power Factor)
Pre-Fault Load
Superimposed
Figure 4-17. Relay 51/27R Coordination With 67 Relay for Fault 3 In Figure 4-16