Deep-well pump motors

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Both bimetal types may be provided with means of compensating for ambient temperature, which may be desirable if the motor and control are in dtssimilar environments. For example, a motor in a deep well pump is in a constant ambient temperature, while its surface control is in a variable ambient. Where motor and heater are located in the same ambient, compensation may actually be harmful. The overload relay is supposed to track the thermal conditions in the motor windings, and a compensated overload would ignore the ambient portion of the total heat present. 

The application and use of deep-well turbine and submersible pumps, is extensive and a choice will depend upon the depth of liquid and the rate of discharge. In rocky areas, where the digging of larger well cavity is a difficult task, submersible pumps provide an easy alternative. Similarly, for higher heads and where only a small quantity of liquid is to be pumped, these pumps are preferred. We discuss below the characteristics of these motors and the application of these pumps. 

A more economical alternative is found in a submersible pump where the pump, directly coupled with the prime mover, is slid into the tubewell through narrow pipes. Narrow pipes are easy to sink into rocky terrain or very deep water levels. They are less expensive and are easy to install due to the elimination of the need for a pump house. Once the unit is slid into the well it requires little maintenance. (See Figures 7.5-7.7.) Such pumps have a standard centrifugal multistage arrangement, and the motors are required to work under water or any other liquid. These motors have an exclusive application for submersible pumps. 

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