Method for contactless determination of an operating state

A compressor comprising:

• a compressor drive comprising an electric motor, the electric motor comprising a motor lead having a plurality of phases;
• a power supply cable in communication with the plurality of phases of the motor lead to supply electrical power to the electric motor to drive the compressor;
• a detection element attached to the motor lead and positioned to detect a magnetic field associated with at least one of the plurality of phases of the motor lead;
• and
• a machine controller in communication with the compressor drive and detection element to receive the magnetic field detected by the detection element over a time range, to determine a frequency spectrum of the magnetic field over the time range, and to analyze the frequency spectrum of the magnetic field over the time range to determine an operating state of the compressor or a rotational speed of the compressor drive.

A method for determining an operating state of a compressor or a rotational speed of a compressor drive of the compressor, the method comprising:

• detecting a magnetic field associated with at least one phase of current supplied to a motor lead of an electric motor of the compressor drive using a detection element attached to at least one phase of a power supply, the power supply supplying electrical power to the electric motor to drive the compressor, wherein the magnetic field is detected over a time range;
• determining a frequency spectrum of the magnetic field over the time range;
• and
• using a clustering method and a classification method to determine the operating state of the compressor.