SWITCH AND BY-PASS/ISOLATION SWITCH.
2.12
GOVERNOR
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NOTE: Coordinate with paragraph ENGINE GENERATOR
PARAMETER SCHEDULE.
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Each engine shall be provided with a governor which maintains the frequency
within a bandwidth of the rated frequency, over a steady-state load range
of zero to 100% of rated output capacity. The governor shall be configured
for safe manual adjustment of the speed/frequency during operation of the
engine-generator set, without special tools, from 90 to 110% of the rated
speed/frequency, over a steady state load range of 0 to 100% or rated
capacity. [Isochronous governors shall maintain the midpoint of the
frequency bandwidth at the same value for steady-state loads over the range
of zero to 100% of rated output capacity.] [Droop governors shall maintain
the midpoint of the frequency bandwidth linearly for steady-state loads
over the range of zero to 100% of rated output capacity, [with 3% droop]
[configured for safe, manual, external adjustment of the droop from zero to
[7] [_____] %].]
2.13
GENERATOR
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NOTE: Armature and field winding insulation classes
are specified based on the allowable temperature
rise (the temperature in the windings above the
temperature of the air used to cool the windings).
See NEMA MG 1 for a discussion of the classes with
respect to size range, elevation, method of
measurement, and ambient temperature. Select the
class insulation for each application based on
operating conditions. Class F is considered
industry standard. If a different class is required
for different machines, specify the one for each
application in the Parameter Schedule for the
respective genset.
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Each generator shall be of the synchronous type, one or two bearing,
conforming to the performance criteria in NEMA MG 1, equipped with winding
terminal housings in accordance with NEMA MG 1, equipped with an
amortisseur winding, and directly connected to the engine. Insulation
shall be [Class H] [Class F]. Generator design shall protect against
mechanical, electrical and thermal damage due to vibration, 25% overspeeds,
or voltages and temperatures at a rated output capacity of 110% for prime
applications and 100% for standby applications. Generator ancillary
equipment shall meet the short circuit requirements of NEMA MG 1. Frames
shall be the drip-proof type.
2.13.1
Current Balance
At 100% rated output capacity, and load impedance equal for each of the 3
phases, the permissible current difference between any 2 phases shall not
exceed 2% of the largest current on either of the 2 phases.
SECTION 16263A
Page 52
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