A submersible motor is an electrical device used to drive a submersible pump. It is filled with non-toxic oil or antifreeze liquid. It is ideal for pressure-boosting systems with a submersible pump for conveying utility or drinking water. Submersible motors are completely sealed and can operate under very high pressure. They are made of stainless steel, which provides exceptional durability and reliability. Most of them are manufactured to the NEMA standard.
Technical specifications and construction of submersible motors
A good submersible motor guarantees the safe, long-term operation of the pump. Submersible motors provide variable torque in submersible pumps. The housing of submersible motors is made of AISI 304 stainless steel. The upper part of the body is usually made of cast iron and protected with an anti-corrosion coating. The shaft of a submersible motor is designed for intensive operation and is resistant to mechanical overloads and damage. Ball bearings and a mechanical seal made of graphite and ceramic are also very important components of a submersible motor. In the case of submersible motors, there is no risk of oil escaping beyond the external insulation—the entire construction is exceptionally watertight. A submersible motor is designed for continuous operation.
The most important technical parameter of submersible motors is the maximum immersion depth, which should not be less than 100 meters. It is also worth paying attention to the permissible voltage fluctuations, water temperature, degree of protection, and insulation class of the winding. A high-performance submersible motor will be able to start at least 20 times per hour. The motor’s bearing assembly is lubricated by the liquid filling the motor, which dissipates its energy losses. The design of connections and couplings in a submersible motor is standardized and accepted by all submersible pump manufacturers. A submersible motor may be single-phase or three-phase.
Safe and functional submersible motors
Submersible motors are designed to operate in both vertical and horizontal positions. They are equipped with waterproof electrical connectors, while their seals, cables, and windings meet the highest European quality standards. They comply with strict standards and must bear the CE mark of conformity. Their efficiency should exceed 70%. In terms of operating characteristics, the rated power and rotational speed of the submersible motor are particularly important. Submersible motors should not be operated at frequencies exceeding their rated values, which are usually 50 and 60 Hz. Submersible motors are powered by 230V or 400V. A submersible motor should be selected with one power rating higher than the value specified in the pump selection chart. A submersible motor is protected against short circuits, overloads, phase failure, supply asymmetry, undervoltage, and excessive numbers of starts.
Nowadays, four-inch submersible motors manufactured in accordance with the ISO 9001 standard are the norm. 6”, 8”, 10”, and 12” motors are also available on the market, with power ratings ranging from 0.25kW to 400kW. Submersible motors operate maintenance-free and are equipped with self-regenerating stator resin that protects the motor against damage. Systems working with submersible motors are used not only to supply drinking and utility water in households, water supply facilities, and agriculture, but also for drainage and pressure boosting.
