A screw compressor is provided including a casing having a suction port and a discharge port, a male rotor rotatable relative to the casing about a first axis, a female rotor rotatable relative to the casing about a second axis, and a magnetic gear system. The magnetic gear system includes a first magnetic gear associated with the male rotor and a second magnetic gear associated with the female rotor. The first magnetic gear and the second magnetic gear are positioned such that a magnetic field of the first magnetic gear interacts with the second magnetic gear to drive rotation of the female rotor about the second axis.

A screw compressor (12) includes a casing (20) having a suction port and a discharge port, a male rotor (28) rotatable relative to said casing about a first axis (A), a female rotor (30) rotatable relative to said casing about a second axis (B), and a magnetic gear system including a first magnetic gear (60) associated with said male rotor and a second magnetic gear (62) associated with said female rotor. The first magnetic gear and the second magnetic gear are positioned such that a magnetic field of said first magnetic gear interacts with said second magnetic gear to drive rotation of said female rotor about said second axis.

A pump monitoring system is provided, the pump including a rotor, and stator, the system including a magnetic field sensor to measure a magnetic field generated by a magnet positioned on a rod above the rotor; and a computer system configured to use the magnetic field to determine the rotor position. The magnetic field generated by the magnet can be used to determine characteristics of the pump including slipping and sticking, twist and twist differential, togging and wobble.

A motor-driven compressor includes a metal housing accommodating a compression unit and an electric motor and a resin cover coupled to the housing. The cover and the housing define an accommodation chamber that accommodates a motor driving circuit that drives the electric motor. A metal shield is fixed to the cover and blocks electromagnetic noise. The shield and the cover are stacked together. A sealing member located between the shield and the cover. The sealing member is configured to block entry of foreign matter into the accommodation chamber through a gap between the shield and the cover.

A pump monitoring system is provided, the pump including a rotor, and stator, the system including a magnetic field sensor to measure a magnetic field generated by a magnet positioned on a rod above the rotor; and a computer system configured to use the magnetic field to determine the rotor position. The magnetic field generated by the magnet can be used to determine characteristics of the pump including slipping and sticking, twist and twist differential, togging and wobble.