Busbar
voltage
Main feeder current
Stand-by feeder current
Main feeder breaker (CB1)
Stand-by feeder breaker (CB2)
Main feeder breaker open
command (OPEN_CB1)
Stand-by feeder close
command (CLOSE_CB2)
1 2 3 4
CB open
delay
CB close
delay
Internal Logic + BO delay
Figure 943: Signal diagram of a fast sequential transfer (FBBM) (For simplicity
reasons only one voltage is presented in the figure)
1
External fault begins
2 Main feeder breaker open command (OPEN_CB1)
3 Main feeder breaker opens, stand-by feeder close command (CLOSE_CB2)
4 Stand-by feeder breaker closes
If DISA_RUN input is active, transfer is not allowed to complete until input is
deactivated.
When fast sequential transfer is completed, this is indicated with COMPL_FBBM
output.
1st phase transfer
The transfer at the 1
st
st phase coincidence is executed when there are no
synchronized conditions present at the moment of the transfer initiation, so that
no fast transfer can be carried our due to physical reasons.
Initial conditions required for 1
st
phase transfer initiation are (transfer from feeder 1
to feeder 2):
• DISA_1ST_PH is FALSE
Control functions
1MRS759142 F
1776 REX640
Technical Manual
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