• DISA_1_2 is FALSE
• GRAD_FAIL is FALSE
• Setting Ena 1st Ph transfer is “1>2” or “both”
• READY (from Evaluation module) is TRUE
• If transfer is initiated manually, then ENA_FASTONLY must be FALSE
First the main supply feeder will be opened without delay. Once the supply feeder
breaker opens, the connected busbar is without power supply and will run down in
accordance with its specific characteristic curve.
For the connection of the stand-by feeder, variety of points in time are possible at
which circuit breaker closing is possible with minimal stress to the system. Closing
of the circuit breaker is timed is such way that at the closing time of the breaker,
phase angle difference between stand-by feeder and busbar is close to zero.
The HSABTC determines the course of the difference voltage and the point in
time of the 1st phase coincidence through anticipatory computation. In order to
compensate for the installation-specific processing time (system response time,
circuit breaker operating time), the close command is issued accordingly before the
actual first minimum of the difference voltage occurs within a previously defined
connection window.
1
2
3
4
5
6
Main feeder
breaker
Stand-by
eder breaker
Main feeder
breaker open
command
Stand-by
feeder close
command
CB close
Figure 944: Signal diagram of 1
st
phase transfer
1MRS759142 F
Control functions
REX640
Technical Manual
1777
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