SME Heat Exchanger Motors
SME now offer a complete range of water filled, water tight, submersible motors with integral heat exchangers in the 10",12",14" and 16" for 2 pole and 4 pole speeds.
These motors offer a significantly lower temperature rise when compared with standard submersible motors. This is an advantage that can be utilized when customers want to operate in water with a high ambient temperature or when there will be minimal cooling water flow.
Even with the standard applications the lower temperature rise will extend the life of the motor significantly. There is an accepted rule of thumb for electrical insulation that its life is shortened by one half for every 10°C increase in operating temperature. The winding operating temperature for a normal water filled submersible motor is about 70 Deg. C in 25 Deg. C. water, while an SME Heat Exchanger Motor will be running at about 45 Deg. C. - this is 25 Dec. C. cooler. This magnitude of difference in temperature rise will have a significant positive impact on motor life.
The basic design principle for these motors is to circulate the internal water in the motor to remove the heat from the "active" parts of the motor and then pass it through a heat exchanger which brings the internal water back to somewhere close to the external ambient water temperature - before feeding it back through the "active" parts again to remove more heat. The heat exchanger increases the external surface area of the motor by 50% and the water circulation allows the heat to dissipate more evenly and quickly out of the motor and into the external water. The small impeller inside the motor that circulates the water has an insignificant impact on the motor efficiency in terms of additional load, while the motor has an improved efficiency because the stator and rotor copper losses are reduced due to the lower operating temperature.
Motor Thermal Protection Unit
All SME Heat Exchanger Motors come with four (4) PT100 temperature sensors installed in the motor.
(1) one PT100 is attached to the thrust bearing assembly which will detect excessive thrust loads and overheating in the thrust bearing.
(1) one PT100 is installed in the end winding on the non drive end of the motor.
(1) one is installed half way down the slot in the winding in the middle of the motor.
(1) one is installed in the end winding on the drive end of the motor.
SME can offer one temperature protection unit (SME4TM) to monitor all 4 PT100'S installed in the SME Heat Exchanger Motor.
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