appendix

Application Manual – Liquid Cooled Generator Sets
Altitude and Ambient Temperature
Based on geographic location, the size of the generator set the software recommends
may be increased for a given level of performance as altitude and/or ambient
temperature increase. The default values are an altitude of 500 feet (152 meters) and an
ambient temperature of 77° F (25° C).
Sound Attenuation
The default setting is None. However, a Quiet Site generator set may be selected. Quiet
Site units include special exhaust silencers, a sheet metal housing with sound attenuating
insulation, and/or intake and discharge dampers. Not all models are available in a Quiet
Site configuration. When selecting Sound Attenuation, GenSize generator set
recommendations will be limited to standard optional packages available from the factory.
Your local distributor, however, should be consulted for any other sound attenuation
needs.
Maximum Alternator Temperature Rise
A maximum allowable temperature rise over an ambient of 40° C (104° F) can be
specified for the alternator windings. GenSize will recommend engine–alternator
combinations that limit the alternator temperature rise to the specified temperature when
powering the specified connected loads. It may be desirable to use lower temperature
rise alternators in applications that contain significant non–linear loads, where better
motor starting is required, or in prime duty applications. The default setting is 125° C.
Note that, when you select a lower temperature rise alternator, you may increase the size
of the recommended generator set to accommodate a larger alternator.
Fuel
The default fuel is Diesel. Other choices of available fuels are Natural gas and Liquid
Propane Gas. An “Any Fuel” choice is available which allows GenSize to compare the
performance of all available fuel choices.
Note: For gaseous fuels requirements above approximately 150/140 kW, consult the distributor.
Frequency
Specify the required operating frequency. Generator sets are configured for either 50 Hz
or 60 Hz. The default value is 60 Hz.
Phase
Select either a single– or three–phase generator set. The default setting is three–phase.
If selecting single–phase, only single–phase loads are allowed. Selecting single–phase
will also limit the number of available models since larger generator sets are not available
with single–phase generators. The default three–phase selection permits single–phase
loads but GenSize assumes that the single–phase loads will be balanced across the
three phases.
Duty
GenSize makes a recommendation based on the standby or prime power rating of the
generator set, derating appropriately for site conditions. The default setting is Standby.
For further discussion and illustration of system and generator set ratings see Preliminary
Design section.
A standby power system is an independent power system that supplies a facility in the
event of a failure of the normal power source. (It is assumed that the generator set is
isolated from the utility service.) The standby power rating is applicable for emergency
power duty for the duration of a typical power interruption. No overload capability is
available for this rating.
A prime power system is an independent power system for supplying electric power in
lieu of purchasing power from a commercial utility. (It is assumed that the generator set
is isolated from the utility service, or that utility service is unavailable.) The prime power
rating is the maximum power available at variable load for an unlimited number of hours.
A–6 APPENDIX A
Rev. Jan 2011