Application Engineering

Please read the Warranty Statement carefully before proceeding with any design or ordering materials or labor.

These documents are in PDF format. To view them, you will need Adobe Reader® software.

The Appendices contain useful information and tools for specific generator applications as well as more general information.

The Cummins Power Suite CD contains applications such as GenSize, for determining the correct capacity of generator set for standby and prime power applications.

Using GenSize, the user can create project files with load information that can be copied and pasted between projects, modified, saved and retrieved.

GenSize features a large number of pre-defined load characteristics that can be tailored by the user to the individual application needs. Sample loads include battery charging, uninterruptible power supplies, motors, fire pumps and general lighting and socket (receptacle) loads.

The reduced voltage motor starting section highlights the advantages of different motor starting systems on generator sizing. This is particularly important where a single large motor represents a high proportion of the load, where useful cost savings can be made.

The World voltages and supplies section details the most common voltages and frequencies for many countries of the world.

Maintenance and Service gives typical maintenance schedules for generators used in both prime power and standby applications.

The chapter ends with a useful glossary of terms used in power generation.

Requirements and Recommendations:

• When entering a project into GenSize ensure that the project parameters are correctly set to the actual site conditions. These may not necessarily be the same as local meteorological data due to solar radiation, prevailing wind, other heat sources etc.
• The 10% overload capacity applies only to Prime Power rated generator sets on variable load - not all generator sets are available for Prime Power rating.
• Loads can be entered into a sequence within GenSize. If the largest motor is started first, a smaller generator selection may be possible. However, if the large motor then stops, other loads may have to be removed in order to re-start the motor if this method is used.
• Reduced voltage starting will lessen the starting kVA of motors. Ensure that sufficient torque remains to accelerate the motor with its load if reduced voltage starting is used.
• Using rotor resistance starting lessens the starting kVA but increases the load on the engine due to the high starting power factor.
• Variable frequency drives give may impose high levels of harmonic distortion particularly when running at light loads or during starting.
• Star-delta started motors must reach full synchronous speed before transition to delta; otherwise the generator must be sized to meet the transition surge, which can be almost as great as for across-the-line starting.
• Where closed-transition starting is used, ensure that the generator is sized to meet the requirements of the resistor or reactor unit in the motor drive.

For information regarding your application contact your nearest distributor.

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