A method of monitoring an air filter in a heating, ventilation, and air conditioning (HVAC) system that includes operating a blower motor at a desired torque; monitoring a horsepower of the blower motor over a selected time period when the blower motor is operating at the desired torque; determining a moving average of the horsepower of the blower motor over the selected time period; detecting when the moving average drops below an established baseline moving average by a selected percentage; and activating a notification to check or change the air filter of the HVAC system.

Apparatus (10) for monitoring the condition of an item of electrical equipment (1) whilst in operation comprises a vibration sensor (11) and an electrical sensor (12) operable to detect a characteristic operational electrical signal of the equipment (1). The output of the vibration sensor (11) and the electrical sensor (12) is supplied to a spectrum generator (13) and then to a processing unit (14) operable to process the respective frequency spectrums to generate a frequency response function. Once a frequency response function is generated, the processing unit (14) is operable to compare the generated frequency response function to a model frequency response function. This allows any variations between the generated frequency response function and the model frequency response function to be identified. This could be indicative of a fault and could provide an identification of the nature of the fault.

A method of monitoring an electrical machine, wherein the method includes: a) obtaining temperature measurement values of the temperature at a plurality of locations of the electrical machine, b) obtaining estimated temperatures at the plurality of locations given by a thermal model of the electrical machine, the thermal model including initial weight parameter values, c) minimizing a difference between the temperature measurement values and the estimated temperatures by finding optimal weight parameter values, d) storing the initial weight parameter values to thereby obtain a storage of used weight parameter values, and updating the optimal weight parameter values as new initial weight parameter values, and repeating steps a)-d) over and over during operation of the electrical machine.

An apparatus that detects a rotor input is provided. The apparatus includes a rotor comprising at least a portion which is configured to rotate around an axis of rotation; a reactance element disposed in the rotor, a sensing medium member disposed in the rotor, and a motion conversion member configured to move in the rotor based on a rotation of the portion of the rotor, and configured to move together with the sensing medium member to change a reactance of the reactance element according to the rotation of the portion of the rotor.

Systems and methods relate to electric propulsor fault detection. An exemplary system includes at least a first inverter configured to accept a direct current and produce an alternating current, a first propulsor, a first motor operatively connected with the first propulsor and powered by the alternating current, and at least a noise monitoring circuit electrically connected with the direct current and configured to detect electromagnetic noise and disengage the at least an inverter as a function of the electromagnetic noise.

A method of monitoring the performance of a multi-phase electric motor (13), wherein the electric motor comprises a plurality of stator windings (7, 8, 9) connected in a wye configuration to form a wye point. The method comprises measuring an electrical characteristic of the wye point in a time domain; based upon the measured electrical characteristic of the wye point in the time domain, determining an electrical characteristic of the wye point in the frequency domain; and deriving data indicative of at least one parameter of the performance of the electric motor based upon the determined electrical characteristic of the wye-point in the frequency domain.

Complicated system fault diagnosis method and system based on a multi-stage model are provided. The method includes: establishing an integer-order mathematical model, a 0.1-level fractional order mathematical model, and a 0.01-level fractional order mathematical model of a permanent magnet synchronous motor system; designing an integer-order status observer based on the integer-order mathematical model, designing a 0.1-level fractional order status observer based on the 0.1-level fractional order mathematical model, and designing a 0.01-level fractional order status observer based on the 0.01-level fractional mathematical model; corresponding residual values can be obtained by the observers and compared with corresponding threshold values to judge whether there is a fault. The system includes first through third modules. Observers with different accuracy degrees are set up and the permanent magnet synchronous motor system is diagnosed through the observers. The fault diagnosis method and system are mainly used in motor diagnosis.

A method of adaptively controlling a brushless DC motor includes steps of: controlling the brushless DC motor rotating at a first speed according to an operation curve, accumulating a running time of the brushless DC motor, estimating a remaining used time of a bearing of the brushless DC motor according to the accumulated running time, executing an alarm operation when the remaining used time is less than a predetermined time, and decreasing the speed of the brushless DC motor to run at a second speed to prolong the used time of the bearing.

A test and measurement instrument includes one or more sensors configured to measure a mechanical position of a synchronous machine driven by analog three-phase signals, a converter to determine an instantaneous electrical angle from the measured mechanical position, a transform configured to generate DQ0 signals based on the instantaneous electrical angle, and a vector generator structured to produce a resultant vector from the DQ0 signals. Methods are also described.

A transportable testing arrangement comprising a testing area configured to receive an electric component to be tested, a removable hood configured to cover the testing area, testing equipment for testing the electric component, a base on which the testing area, the removable hood and at least part of the testing equipment are mounted and a frame on which the base is mounted. The base is mounted on the frame by one or more suspension elements configured to enable movement of the base in relation to the frame, and wherein the base is further configured to be locked in relation to the frame by one or more locking elements to prevent movement of the base in relation to the frame.