Calculating Minimum Cooling Flows

Electric motors convert electrical energy into mechanical energy, making it possible to move things, like water. In the process, electric motors produce heat, and that heat must be displaced. Otherwise, the heat will build up in the motor and cause motor failure. Motors that are located aboveground use the air around them for cooling, sometimes with the assistance of a fan. In the case of a submersible motor, the water being pumped is used to cool the motor and provide a long, reliable service life.

There are two keys to keeping a submersible motor cool: making sure there is water flowing past the motor, and that there is enough of it. Even though the motor is submerged in water, several situations are possible in which water could enter above the motor. In these cases, water will enter at the pump intake and never pass the motor. Examples of this type of situation would be an
open body of water, a pump sitting below the casing/perforations or a top-feeding (cascading) rock well. In these situations, the motor requires a fl ow sleeve. Page 6 of the Franklin Application, Installation, Maintenance (AIM) manual explains how a flow inducer sleeve is constructed. One important note: for the flow sleeve to be effective, it must extend past the bottom of the motor. Once water flow past the motor has been confirmed, the amount of flow must also be checked. Continue reading