Kohler 20EKOZD

261Section 14 Load ManagementTP-6953 7/19
25kW
Critical
loads
Most
important
non-
critical
loads
Least
important
non-
critical
loads
Additional
non-critical
loads
Load
Shed
Panel
Load
Shed
Panel
Generator #1
(50kW rating)
18kW 3kW 10kW 12kW 5kW
15kW
8kW
Generator #2
(50kW rating)
Generator #3
(50kW rating)
14kW 14kW
Figure 14 -9 All Generators Supplying the Paralleling
Bus, Priority 1 Added
With load priority 1 added, the total system load is
43 kW, shared between the three generators. This
amounts to 29% of the rated capacity of the system,
increasing the time delay to add priority 2 to 55 seconds.
With priority 2 online, the system load is 34%, requiring
85 seconds to add priority 3.
With priority 3 online, the system load is 36%, requiring
104 seconds to add priority 4.
With priority 4 online, the system load is 43%, requiring
260 seconds (just over 4 minutes) to add priority 5.
With priority 5 online, the system load is 51%, requiring
2400 seconds (40 minutes) to add priority 6.
After all load priorities are added, Generator
Management may elect to stop a generator, but only if
the stop percentage is above 81% (the load on two
generators). If a generator is stopped, no loads will
shed, as the percent of system capacity is below the
Generator Overloaded Percent (85%).
25kW
Critical
loads
Most
important
non-
critical
loads
Least
important
non-
critical
loads
Additional
non-critical
loads
Load
Shed
Panel
Load
Shed
Panel
Generator #1
(50kW rating)
18kW 3kW 10kW 12kW 5kW
41kW
8kW
Generator #2
(50kW rating)
Generator #3
(50kW rating)
40kW 0kW
Figure 14 -10 Generator #3 Stopped, All Priorities
Added
Note: Priorities 3 and 6 will remain added unless the
system is overloaded, even though they are
controlled by the generator #3 controller, as the
Load Management logic in the generator #3
controller looks at bus frequency and bus loading
to make Load Management determinations.
Note: The case above is unlikely, as Generator
Management will not typically be configured to
stop a generator above 80%, as this does not
leave very much available capacity for changing
loads.
If the Stop Percentage for Generator Management is
changed, it should not be configured to be above the
Generator Overloaded Percent, as Generator
Management may force a priority to shed when a
generator is stopped, nor should t he Start Percentage
for Generator Management be above the Generator
Overloaded Percent, as this may result in loads being
shed while an available generator does not start to
supply the loads.
If the Minimum Load Priority Online for Generator
Management is set to 6, the third generator will start as
soon as Load Management sheds priority 6. This would
result in priority 6 re-adding and the generator stopping
again, establishing a repeating cycle.
Overload Shed and Underfrequency Shed use identical
timing and thresholds to the single generator case, but
use the bus % kW and the bus frequency to make Load
Management determinations.