device shall provide an adjustable setpoint range from 50 to 100%. When
the system load falls below the percentage setpoint of the operating set's
rating for a period of approximately [_____], the controller shall unload
and disconnect engine-generator sets from the system, stopping each
engine-generator set after cool-down.
2.22
MANUAL ENGINE-GENERATOR-SET SYSTEM OPERATION
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NOTE: Delete synchronization for non-parallel
operation.
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Complete facilities shall be provided for manual starting and testing of
each set without load, loading and unloading of each set, and
synchronization of each set with an energized bus.
2.23
STATION BATTERY SYSTEM
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NOTE: The station battery system should be shown on
the drawings.
Delete this requirement when not needed. A station
battery is required only when dc-operated devices
other than engine starting motors are provided. The
station battery and starting battery may be combined
where all dc-operated devices are the same voltage
level and are not affected by the voltage drop
caused by engine starting. Because lead calcium
batteries are more economical and require less
maintenance, nickel cadmium batteries should be
specified only where very high discharge rate with
constant voltage over a short period of time is
required, or for applications where the battery
temperature cannot be maintained above minus 6
degrees C (22 degrees F). Slush does not begin to
form in lead acid batteries until the temperature
reaches minus 29 degrees C (minus 20 degrees F), but
the battery voltage output and current capacity fall
below useful values at minus 6 degrees C (22 degrees
F). The designer should provide measures to
maintain battery temperature between 16 and 32
degrees C (60 and 90 degrees F); 25 degrees C (77
degrees F) is the target temperature for optimum
service life and performance. The engine starting
battery for smaller size sets is sufficient for dc
requirements and a station battery is not required.
Define loads which are to be served by the station
battery.
Calculations of battery capacity utilize a median
temperature of 25 degrees C (77 degrees F). If the
predominate battery operating temperature varies by
more than + 2.5 degrees C (+ 5 degrees F) from 25
degrees C (77 degrees F), specify the median
operating temperature.
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SECTION 16263A
Page 65
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