System for protecting bearings and seals of a refrigerant compressor

A. compressor system, comprising:

• a conductive housing made of a conductive material, the conductive housing includes a motor housing and a compressor housing;
• a refrigerant disposed within the conductive housing;
• a motor that includes a rotor, a shaft extending from the rotor, a stator winding disposed within the motor housing in proximity with the rotor, and a bearing supporting the shaft and the rotor within the motor housing;
• a lubricant lubricating the bearing, wherein the lubricant at the bearing includes at least a trace of the refrigerant;
• a compressing element disposed within the compressor housing and being coupled to the rotor such that rotation of the rotor motivates the compressing element to compress the refrigerant;
• a labyrinth seal in general proximity with the compressing element, wherein the refrigerant at the labyrinth seal includes at least a trace of the lubricant;
• an adjustable frequency drive that provides the stator winding with three-phase electrical power to rotate the rotor;
• three conductors electrically coupling the adjustable frequency drive to the stator winding such that the three conductors can convey the three-phase electrical power to the stator winding;
• an inductor comprising a ring of magnetic material that encircles the three conductors;
• and
• a ground return path conductor made of a material that is more electrically conductive than the conductive material of the conductive housing, the ground return path conductor extends from the adjustable frequency drive to a point on the conductive housing, wherein the point is closer to the bearing than to the labyrinth seal.

A compressor system, comprising:

• a conductive housing made of a conductive material, the conductive housing includes a motor housing and a compressor housing;
• a refrigerant disposed within the conductive housing;
• a motor that includes a rotor, a shaft extending from the rotor, a stator winding disposed within the motor housing in proximity with the rotor, and a bearing supporting the shaft and the rotor within the motor housing;
• a compressing element disposed within the compressor housing and being coupled to the rotor such that rotation of the rotor motivates the compressing element to compress the refrigerant;
• an adjustable frequency drive that provides the stator winding with three-phase electrical power to rotate the rotor;
• three conductors electrically coupling the adjustable frequency drive to the stator winding such that the three conductors can convey the three-phase electrical power to the stator winding;
• an inductor comprising a ring of magnetic material encircling the three conductors;
• and
• a grounding contact device supported by the motor housing and being in electrical contact with the shaft;
• and
• a ground return path conductor extending between the adjustable frequency drive and the conductive housing, wherein the ground return path conductor is of a material that is more electrically conductive than the conductive material of the conductive housing.

A compressor system, comprising:

• a conductive housing;
• a refrigerant disposed within the conductive housing;
• a motor that includes a rotor, a shaft extending from the rotor, a stator winding disposed within the conductive housing in proximity with the rotor, and a bearing supporting the shaft and the rotor within the conductive housing;
• a compressing element disposed within the conductive housing and being coupled to the rotor, such that rotation of the rotor motivates the compressing element to compress the refrigerant;
• an adjustable frequency drive with a plurality of switching devices that provide the stator winding with three-phase electrical power to rotate the rotor and the shaft at various speeds including a certain rated speed and torque;
• three conductors electrically coupling the adjustable frequency drive to the stator winding such that the three conductors can convey the three-phase electrical power to the stator winding and upon doing so the conductive housing is subjected to a composite adverse voltage that is comprised of a plurality of component voltages including a high frequency shaft voltage and an operationally induced shaft voltage, wherein:
• a) a high frequency common mode voltage is caused by a switching operation of the plurality of switching devices and exists between the conductive housing and the stator winding;
• b) the high frequency common mode voltage drives a high frequency common mode current through the conductive housing;
• c) the high frequency common mode current passing through the conductive housing creates a high frequency internal voltage;
• d) the high frequency internal voltage provides the high frequency shaft voltage between the conductive housing and the shaft;
• and
• e) the operationally induced shaft voltage exists between the conductive housing and the shaft and is influenced by at least one of an imbalanced ampere-turns of the stator winding, a stator winding asymmetry, a rotor asymmetry, and an electrostatic charge due to operation of the compressor system;
• an inductor comprising a ring of magnetic material and being in an installed position encircling the three conductors, however, the adjustable frequency drive can power the stator winding to rotate the rotor at the certain rated speed and torque even if the inductor were omitted such that at the certain rated speed and torque the high frequency common mode current has a frequency that is lower by a certain percentage when the inductor is in the installed position than if the inductor were omitted, and the certain percentage is such that the inductor has a greater effect an the high frequency common mode current than on the high frequency common mode voltage, and the inductor has a greater effect on the high frequency common mode current than on the operationally induced shaft voltage, the certain percentage is sufficient to appreciably mitigate the composite adverse voltage.