Abstract: A commutation system for a DC motor having a stator including a plurality of windings and a permanent magnet assembly, the assembly has a housing; at least three collector segments connected to stator windings inside the housing; and a rotor assembly in the housing having brushes for connecting the collector segments, the brushes extending from the rotors parallel to the motor axis; wherein the brushes are attached to the rotors to rotate coaxially to each other and contact the surfaces of the collector segments. The system includes proper mechanism for heat conduction from the brushes sliding surface to the external wall. Damping is provided to limit resonance in the commutation system. Also air filtering can be provided to insure clean operation.

Abstract: A commutation system for a DC motor having a stator including a plurality of windings and a permanent magnet assembly, the assembly comprising: a housing; at least three collector segments connected to stator windings inside the housing; and a rotor assembly in the housing having brushes for connecting the collector segments, the brushes extending from the rotors parallel to the motor axis; wherein the brushes are attached to the rotors to rotate coaxially to each other and contact the surfaces of the collector segments. The system includes proper mechanism for heat conduction from the brushes sliding surface to the external wall. Damping is provided to limit resonance in the commutation system. Also air filtering can be provided to insure clean operation.

Abstract: An oil filter for use in an electric motor forming part of a downhole device such as an ESP, comprising a two-part filter including a first part formed from a porous material which acts to filter solid particulate material from the motor oil, and a second part comprising a sorbent for removing aqueous liquids from the motor oil.

Abstract: A method of controlling operation of an ESP, comprising determining at least one operating speed (rpm) at which the ESP experiences unacceptable levels of lateral vibrations; and applying a periodic modulation to the operating speed when operating the pump at the determined speed to damp the lateral vibrations.