In the May/June 1997 issue of Franklin Aid, we introduced Franklin’s new 8-inch Severe Duty motor. Since then we have been receiving questions about writing specifications. Below you will find typical specifications for the Severe Duty motor. If you require specifications for Franklin Electric’s water well submersible motors please call our Hotline.

Ratings:The submersible motor shall be of a construction suitable for continuous under-water operation and must be capable of operating in 90°C (195°F) well fluid with a flow velocity past the motor of 0.5 ft/sec or more. The motor shall be rated to produce _____ horsepower with _____ volts, _____ frequency (Hz), 3 phase alternating current power with a Service Factor of 1.15 (60 Hz). All insulating materials will be Class H or better and the stator is to be of an oil-filled rewindable type.

Fill Solution: The motor will be filled with a high dielectric mineral oil of an FDA or Pharmaceutical grade with no additives hazardous to human health.

Shaft Seal System: The motor is to be equipped with two independent mechanical shaft seals located at the pump end of the motor shaft. The outer seal will have silicone carbide/silicone carbide mating parts and the inner seal shall be of carbon/ceramic construction.

The fluid between the shaft seals will be positively seperated from the stator area fluid. The motor shall contain a balance tube from the bottom of the motor into the fluid block area between the seals. A spring-loaded diaphragm shall provide positive pressure to prevent well fluid from entering past the seals. All fluid communication tubes will be located within the stator shell.

Stator Area Fluid System: A separate pressure equalizing system will be used to balance the pressure inside the motor with the well bore and provide thermal expansion and contraction capabilities. The fill fluid will be circulated through the motor to ensure proper cooling of the rotor, stator, and bearings.

Bearings: Internal motor bearings will be of the fluid film type. Bronze sleeve bearings shall be provided at each end of the rotor. The thrust bearing will be of an equalized pivoting shoe type with a self-aligning spherical mount and will have a minimum load rating of 10,000 lbs.

Mounting Dimensions: All pump end mounting dimensions and shaft spline configuration will conform to standard NEMA specifications.

Technical Corner

I’m setting a 5 Hp, single-phase motor 65 feet down. The service entrance is right at the well head. Can I use #14 wire even though Franklin’s wire chart leaves it blank?

Can I use smaller wire that Franklin’s wire charts list on shorter runs?

Why do Franklin’s wire charts have blanks or zeros before the first lengths shown?

Franklin’s wire charts for sizing are based on the US National Electrical Code (NEC) for ampacity. Using wire smaller than listed on the chart means the wire is not sized to handle the amps the motor will require. If the wire is required to handle higher amps that it should, the heat build-up can be enough to melt wire insulation and the wire itself. In three-phase applications this leads to single-phasing and potential motor failure. In addition as heat builds up the resistance of the wire increases. As the resistance increases the voltage decreases. If the voltage becomes low enough the motor fails. Even though the distance is less than the wire chart minimums shown, you must have wire large enough to handle the amperage.