Manual 26174
EGCP-2 Engine Generator Control Package
Woodward
137
Point F
The third unit closes its breaker to the two units already on the isolated bus.
Since the rated load delay is in effect, and the system load is above 100% of the
generating capacity on line, the third unit immediately goes to load sharing,
without any load ramping. System load drops immediately to approximately 55%
when the third unit closes its breaker to the bus.
Point G
A step load decrease on the bus brings the system load down to approximately
35%. All three generators remain on line in isochronous load sharing.
Point H
A further step load decrease on the isolated bus brings the system load below
the Min Gen Load set point of 25% to approximately 10%. The master begins
timing for the Reduced Gen Dly time of 30 seconds.
Reduced Load Dly
—Only on the Master controls Sequence Status screen, to
the right of this item, you can see the delay time being counted down from 30. It
will keep repeating this countdown and continue to stop units until the system
load level increases above the Min Gen Load set point or until all units have been
sequenced off.
Point J
Since the system load is still below 25%, and the master’s Reduced Gen Dly
timer has expired. The master unit issues a command to Unit 3 (network priority
3) to off load and opens its gen breaker. Unit 3 begins to ramp off load. System
load begins increasing. The master begins its Max Stop Time delay of 15
seconds before checking to see system load is low enough to allow sequencing
of another unit off line.
Point K
Unit 3 reaches its unload trip point and opens its generator breaker. The system
load is still below the Min Gen Load set point of 25%. The Master’s Max Stop
Time delay has expired. The master begins timing for the next gen off delay time.
Point L
The system load remains below 25%, and the master issues a command to unit
#2 (network priority #2) to off load.
Point M
Unit 2 ramps off load and opens its generator breaker. This leaves the master
unit (network priority #1) on line supplying the load. When required the master
will sequence units on and off line as shown above and determined by the
sequencing set points in its Sequencing and Comms menu.
The Master unit in any multiple unit EGCP-2 system is always the unit with the
lowest Network Priority setting. All slave units are then sequenced on line in
ascending order of their Network Priority settings, and sequenced off line in
descending order of their Network Priority Settings. The Master is always
responsible for any automatic sequencing of the slave units on and off line.