characteristics can affect: selection of the
governor type, whether it is to be isochronous or
droop, and its steady state bandwidth; selection of
the voltage regulator parameters; transient recovery
time for frequency and voltage; maximum voltage and
frequency deviation for a transient event; and
because of the maximum deviations and transient
recovery times, the sizing or oversizing of the
engine and generator. The notes below are included
to assist the designer in making informed choices
when filling in the Engine Generator Parameter
Schedule.
Power Ratings and Industry Terminology. The
following definitions are from the Electrical
Generating Systems Association Standard 101P, Engine
Driven Generating Sets. Stationary
diesel-engine-driven electric generator sets are
divided into the following four rating categories:
EMERGENCY STANDBY, LIMITED RUNNING TIME, PRIME
POWER, and INDUSTRIAL.
"EMERGENCY STANDBY RATING means the power that the
generator set will deliver continuously under normal
varying load factors for the duration of a power
outage." It must be understood that this definition
uses the term "normal varying load conditions".
Most manufacturers use this terminology to indicate
that their units typically are not rated for
continuous operation at the nameplate rating, but
rather that the units provided are rated for
continuous operation at 70% to 80% of their
nameplate rating, with periodic loading up to 100%
of the nameplate rating for short (cyclical) periods
during a power outage. When specifying a genset be
sure to specify what the peak load is and how much
is continuous.
"LIMITED RUNNING TIME RATING means the power that
the generator set will deliver when used as a
utility type power source, typically in load
curtailment type service, for a limited number of
hours, where there are non-varying load factors
and/or constant dedicated loads."
"PRIME POWER RATING means the power that the
generator set will deliver when used as a utility
type power plant under normal varying load factors
to run continuously. This rating requires a minimum
momentary overload capability of 10%."
"INDUSTRIAL RATING means the power that the
generator set will deliver 24 hours per day when
used as a utility type power plant where there are
non-varying load factors and/or constant dedicated
loads."
Overload Capacity.
Overload capacity is only for
PRIME rated units.
Delete for standby applications.
SECTION 16263A
Page 17
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