An apparatus for locating partial discharges in a medium-voltage or high-voltage operating equipment comprises a signal detection device for detecting an electrical signal variable of the operating equipment, a filter device for low-pass filtering of the detected electrical signal variable dependent upon a filter cut-off frequency, a time detection device for detecting a signal propagation time of the low-pass-filtered electrical signal variable, and a comparison device for comparing the detected signal propagation time detected dependent upon the filter cut-off frequency with a reference propagation time for a charge pulse conducted through the operating equipment in order to determine a location of the partial discharge in the operating equipment dependent upon the result of the comparison. Also provided is a method for locating a partial discharge in medium-voltage or high-voltage operating equipment, in particular, using the apparatus.

The short-circuit detection device according to the present disclosure includes: a signal acquisition unit configured to acquire, from a magnetic flux detector configured to detect a magnetic flux generated in a gap between a rotor and a stator of a rotary electric machine, one detected signal based on the magnetic flux and set the one detected signal as a first detected signal and a second detected signal; a signal processing unit configured to perform frequency analysis on the first detected signal, and generate and decode a voltage signal simulating a voltage state assumed in a normal case; and a signal comparison unit configured to perform comparison between a decoded signal obtained through the decoding by the signal processing unit and the second detected signal transmitted from the signal acquisition unit, to detect a short-circuit in a field winding of the rotary electric machine.

A method and device of determining a fault condition in a synchronous motor including a rotor provided with damper bars and an end ring to which the damper bars are mechanically connected thereby forming a damper cage, wherein the method includes: obtaining a first measurement of an end ring current from a first location along the end ring, processing the first measurement to thereby obtain a processing result, and determining whether a fault condition is present in the synchronous motor based on the processing result.

An electric power conversion device has a function of detecting, at low cost and at an early stage, a sign of insulation failure of a transformer or a rotational machine. This electric power conversion device is provided with an inverter circuit and a PWM signal generation unit that makes a comparison between a carrier signal and a voltage command value and generates a PWM signal for driving the inverter circuit. The electric power conversion device feeds and receives electric power through connection to a transformer or a rotational machine provided with a winding wire. The electric power conversion device is provided with: a current sensor that detects a current to be fed to or received from the transformer or the rotational machine; and a diagnostic unit that diagnoses insulation degradation of the transformer or the rotational machine.

Provided are a short circuit state analyzer to compare difference value when the AC excitation current is applied at a first frequency with a threshold value, to estimate a short circuit resistance from the difference value based on data indicating a relationship between the short circuit resistance and the difference value at the first frequency when the difference value is smaller than the threshold value, to cause an excitation power supply to apply the AC excitation current to the field windings at a second frequency lower than the first frequency when the difference value is equal to or greater than the threshold value, and to estimate the short circuit resistance from a difference value obtained by the AC excitation current at the second frequency based on data indicating a relationship between the short circuit resistance and the difference value at the second frequency.

A short circuit detection system and method that identifies a short circuit between turns of a winding of a permanent magnet machine having a three-phase winding in response to detection of imbalances between the three motor phases at an instant in time. The imbalances are identified by monitoring motor terminal voltages and currents.

A condition-based monitoring system receives a plurality of measurements from sensors measuring mechanical and electrical aspects of a prime mover and a synchronous machine. The condition-based monitoring system determines a correlation between the mechanical measurements and electrical measurements to estimate parameters of the model. The condition-based monitoring system also updates the model as sensors obtain additional measurements during operation of the prime mover.

A method for detecting an electrical fault in the stator of an electric machine is provided, wherein the stator includes multiple groups of windings, wherein the windings of each group are assigned to a respective phase of the electric machine, including the steps of: determining a respective current firstly between a subgroup of one of the groups of windings and a distinct further subgroup of the same group of windings and/or secondly between a subgroup of one of the groups of windings and a neutral point, and/or thirdly between a neutral point and either a further neutral point or to a common neutral point connected to at least the neutral point and the further neutral point, evaluating a fault condition, wherein the fulfilment of the fault condition depends on the respective determined current, and outputting a fault signal to personal and/or a device when the fault condition is fulfilled.

The characteristics of a winding to be tested is allowed to be analyzed more easily and in a shorter time. A testing instrument 1 includes an impulse voltage application capacitor Cs having one end connected to an external terminal T2, a switch SW and a current limiting resistor Rs connected in series between another end of the impulse voltage application capacitor Cs and an external terminal T1, and a parameter calculator 5. The parameter calculator 5 calculates at least one of the value of the equivalent capacitor Cd, the value of the equivalent inductor Ld and the value of the equivalent resistor Rd by performing regression analysis using a measured value of a voltage Vcd in an analysis time period Ta from turning on of the switch SW to start of resonance based on the equivalent inductor Ld, the equivalent capacitor Cd and the equivalent resistor Rd pertaining to a winding 11.

Disclosed is a method and apparatus for real-time estimation of full parameters of a permanent magnet synchronous motor. According to this method and apparatus, it is possible to estimate in real time all four parameters of a permanent magnet synchronous motor without additional signal injection. In addition to the state equation, the “stator current ripple model” is additionally used to fundamentally solve the rank deficiency problem in the state equation without injecting additional signals. All four parameters of a permanent magnet synchronous motor can be estimated in real time.