248 Section 13 Generator Management Information TP-6953 7/19
The Start Percentage should always be at least 10%
higher than the stop percentage.
13.4.5 Stop Percentage
The Percentage of Rated Capacity on the other
generators in the paralleling system (the other
generators that are running and are active in Generator
Management) below which a generator is considered
for stopping.
Only a generator which is running (in auto) and is
enabled for Generator Management can be stopped by
Generator Management. Generators running in RUN
(pressing the run button on the front panel) are not
considered for Generator Management (their capacity is
not counted toward supplying the load and they are not
stopped when not needed).
Generator Management uses the stop percentage to
calculate the Stop kW for this generator.
Note: The calculation is based on the capacity of the
other generators on the paralleling bus, as this
generator will not be providing power after it
stops.
The Stop Percentage should be set so that the
generator system keeps enough generators online to
supply any transient loading that the application may
demand (such as large chillers, air conditioners, pumps,
or bow thrusters), while allowing unneeded generators
to stop.
TheStopPercentageshouldalwaysbeatleast10%
lower than the start percentage.
13.4.6 Start Delay
A time factor that represents the time that Generator
Management will wait to start this generator if the load
on the running generators exceeds the Start
Percentage of this generator by 10% and all available
lower-order generators are running.
The Start Delay should be configured to ensure that
reasonable load spikes are handled without starting an
additional generator, while allowing a generator to start
if the increased load persists.
13.4.7 Stop Delay
A time factor that represents the time that Generator
Management will wait to stop a generator if t he load on
the lower-order running generators drops below the
Stop Percentage of this generator by 10% and all
higher-order generators are already stopped.
The Stop Delay should be configured to allow
generators to stop quickly if they will not be needed, but
to prevent g enerators from stopping during a
short-duration light load on the paralleling system.
13.4.8 Stable Delay
The Stable Delay is the delay between the system
reaching a typical loading scenario and Generator
Management becoming active. This delay is intended to
allow any loads connect ed to the system to reac h a
typical load level before Generator Management stops
any generators.
The Stable Delay should be configured to allow the
Generator Management to become active when the
system load has reached a nominal level (all abnormal
load conditions due to a loss o f power have been
removed).
13.4.9 Runtime Threshold
The Runtime Threshold is the maximum Runtime Hour
difference that Generator Management will allow before
starting the lower-hour generator and stopping the
higher-hour generator. This parameter is only
considered with the order selection mode (control
mode) set to Runtime Hours. The Threshold should be
set based on the intended start/stop frequency of the
generators (understanding that changing load may
cause additional start/stop cycles).
13.4.10 Fuel Level Threshold
The Fuel Level Threshold is the maximum Fuel Level
difference that Generator Management will allow before
starting the generator with more fuel and stopping the
generator with less fuel. This parameter is only
considered with the order selection mode (control
mode) set to Fuel Level. The Threshold should be set
based on the intended start/stop frequency of the
generators (understanding that changing load may
cause additional start/stop cycles).
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