Nameplate Motor Horsepower: Relates to the minimum of a range of horsepower. It does not fully reflect the electrical design capability of a motor.
Horsepower at design: Calculated HP of the pump to operate along the design curve
NOL Horsepower: In order to handle the maximum power demanded by the pump at any point along the curve, a maximum power value is calculated as the non-overloading brake horsepower of the pump.
Service Factor: is related to the motor only not the pump operation
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Actual specified motor example: Nameplate Motor Horsepower 1HP
Horsepower at design 1.51HP
NOL Horsepower
2HP
All refers to the same motor/pump
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Bell & Gossett carries an extensive line of wastewater products. Our wastewater pumps have been engineered through extensive testing and development in partnership with our motor vendors to meet specific operating criteria required by our customers. The pump nameplate contains operational information that is important to provide a long life for the pump/motor combination.
Pump horsepower, in many instances does not reflect the full motor shaft horsepower for the pump. Although the motor’s electrical design is similar to that of induction motors for above ground pumps, improved cooling provided by design allows the motor vendor to build the motor to reach the horsepower required to drive the pump over its full range. The temperature rise of the motor is the design criteria used to establish the motor load limits. The same criterion used in Bell & Gossett waste water pumps is the same as used for “standard” non- submersible motors.
The dimensional criteria used to establish the acceptable motor loading is the allowable limits of operating temperature established by NEMA for given motor insulation system. The operating temperature of the motor and the allowable temperature for a class of insulation is the indication of life expectancy. This is used to define motor service factor. The motors we provide will allow operation at all points of the pump curve without exceeding the maximum allowable temperature of the motor insulation system. The motor insulation class used in B&G sewage pumps is a minimum of NEMA Class B. Large commercial sewage pumps are designed with NEMA Class F insulation that has an allowable operating temperature of 155 degrees Celsius and the motor loading is limited to a class B temperature limit of 120 degrees Celsius. This lower temperature limit will give the end user improved motor life.
All B&G wastewater motors are custom designed to provide required power to drive the submersible pump in a continuous duty application pumping raw sewage, within the design working limits of the motor throughout the entire published pump curve. The trim of each impeller rating and the resulting motor loads are selected using motor temperature rise characteristics which are well below the Nema Class B allowed rating. “ We thoroughly test during our product development to insure that our pumps will run anywhere on our published curve and the motor design is key to performance and service life” said Paul Ruzicka, Chief Mechanical Engineer for Xylem Applied Water Systems, based out of Seneca Falls.
Therefore typical service factors are not the consideration when applying the product since the actual service factors of the motors used in the B&G products are not those typically used as defined for standard NEMA motors. All impellers trims and the motor loads that are published use temperature rise as the criteria to insure good motor life.