Techimp Technologies S.r.l.

Techimp Hq S.r.l.

General Electric Company

Techimp-altanova Group S.r.l.

Gian Carlo Montanari

Stefano Serra

Andrea Cavallini

Gaetano Pasini

Fabiano Bettio

Stefano Rolli

Gianpaolo De Robertis

Weizhong Yan

Sameh Ramadan Salem

Abdelkrim Younsi

Fabio Ciani

Francesco Puletti

Davide Fabiani

Dario Andreani

An instrument for detecting partial electric discharges includes: an input stage set up to receive a discharge signal representative of one or more partial discharge pulses and a sync signal representative of an alternating voltage applied to the electric apparatus; a data processing stage for receiving the discharge signal and the sync signal, and extracting substantially in real time for each pulse detected the value of an amplitude parameter, correlated with a pulse amplitude, and the value of a phase parameter, representative of the phase of the voltage applied to the electric apparatus concurrently with the pulse, and transferring to output a processed digital signal including the values extracted. The processing stage includes a filtering module set up to disable substantially in real time the transfer to output of the values of the parameters extracted for one or more pulses.

Instrument and method for detecting partial electric discharges in an electric apparatus

An apparatus for measuring the loss factor of an insulator for medium or high voltages is equipped with a tap adapter forming a point for picking up an electrical signal, and comprises a reference capacitor having a first electrode connected to the tap adapter and a second electrode; a first voltage detection module is connected to the first electrode of the reference capacitor for detecting a signal representative of the voltage applied to the reference capacitor; an active electronic device is connected to earth and to the second electrode of the reference capacitor for keeping the potential of the second electrode at a predetermined reference value; a second voltage detection module is connected to an output of the active electronic device in order to detect a signal representative of the electric current that flows through the reference capacitor.

Apparatus and method for measuring the dissipation factor of an insulator

An apparatus () for measuring the loss factor of an insulator () for medium or high voltages, equipped with a tap adapter () forming a point for picking up an electrical signal (), comprises a reference capacitor () having a first electrode (), which can be connected to the tap adapter (), and a second electrode (); a first voltage detection module () operatively connected to the first electrode () of the reference capacitor () for detecting a signal representative of the voltage applied to the reference capacitor (); a generator module connected to the first electrode () of the reference capacitor () in order to inject a direct electric current into the insulator.

A device () for detecting and processing signals relating to partial electrical discharges in an electrical apparatus () powered by a square-wave () voltage modulated by a modulating wave () in such a way as to form an alternating voltage of predetermined frequency, comprises: a sensor () connectable to the apparatus () for detecting a discharge signal () representing the electrical pulses generated by the partial discharges; a processing unit () connected to the sensor () to receive the discharge signal () and derive the detection instants of each of the pulses detected with respect to a predetermined time reference, a synchronization module () designed to receive an electrical signal () representing the power supply voltage and equipped with a filter () configured for extracting from said power supply signal () a signal () representing the modulating wave (), the processing unit () being configured for associating with the pulses detected the values of a phase parameter (f) representing the phase of the modulating wave () at the pulse detection instants.

Device and method for detecting and processing signals relating to partial electrical discharges

An instrument () and a method for detecting partial electric discharges involve acquiring a discharge signal (), for example picked up by a direct-measuring impedance device () through a broadband HF acquisition channel (), and acquiring the discharge signal () in a narrowband LF acquisition channel () complying with regulations, using on the LF acquisition channel () a trigger controlled in slave mode by a trigger of the broadband HF acquisition channel (); they also involve acquiring another discharge signal () picked up by an indirect-measuring impedance device () through a second narrowband LF acquisition channel (A) and comparing digital signals (A) generated in the first and second LF acquisition channels (A), in order to generate a balanced digital signal () without components representative of common mode electrical signals present in the measuring circuit.

Instrument and method for detecting partial electrical discharges

An instrument () for measuring the loss factor of an electrical apparatus () having an axially extending elongate geometry, in particular a medium voltage cable, comprises: at least a first and a second sensor (A,B) connectable to the apparatus () in a first and a second measuring section (A,B) axially spaced along the apparatus () by a predetermined quantity, respectively, and designed to measure respective values of the magnetic field generated outside the apparatus () by a load current flowing axially through the apparatus; a processing unit () designed to receive the magnetic field values measured by the sensors (A,B) and programmed to derive from them a load loss value as a function of the difference between the measured magnetic field values.

Instrument and method for measuring the loss factor of an electrical apparatus

A method for locating partial discharges occurring at a discharge site () in an electric apparatus () with elongate geometry and generating corresponding electric pulses () propagating in opposite directions along the apparatus () from the discharge site () comprises the steps of detecting () the electric pulses () picked up by a first and a second sensor (), operatively connected to the apparatus () and spaced out along it, and generating corresponding electric signals representative of the waveform of the pulses (), selecting () at least one pair of signals, detected in the consecutive sensors (), and representative of a pair of homologous pulses (), relating to the same partial discharge and propagating in opposite directions along the apparatus, deriving, for the signals of the selected pair of homologous pulses (), at least one attenuation parameter, correlated with a quantity that is variable depending on the distance travelled by the pulses (), calculating () the distance between the discharge site () and the sensors, based on processing the values of the attenuation parameter for the signals of the selected pair of homologous pulses ().

Device and method for locating partial discharges

A method for monitoring an activity of partial electrical discharges in an electric apparatus powered with direct voltage comprises the following steps, repeated in succession at predetermined time intervals: measuring (1) analogue electrical signals and generating corresponding digital signals representative of the wave form of partial discharge impulses; deriving (2) for each of said digital signals, at least one shape parameter and at least one amplitude parameter; separating (3) the set of the measured data into homogeneous sub-sets with respect to the shape parameter; correlating (4) the sub-sets of signals having similar values of the shape parameter and measured in successive steps; selecting (5) the correlated sub-sets for which the amplitude parameter has a predetermined profile over time and attributing the signals of said subsets to partial discharge activities. The methods currently in use do not allow to monitor partial discharge activities in an apparatus in DC, because they do not allow to distinguish the signals relating to the partial discharges from those relating to noise or to disturbances.

Method and an apparatus for monitoring an activity of partial electrical discharges in an electrical apparatus powered with direct voltage

A method for locating partial discharges occurring at a discharge site () in an electric apparatus () with elongate geometry and generating corresponding electric pulses () propagating in opposite directions along the apparatus () from the discharge site () comprises the steps: () of detecting the pulses () picked up by a first and a second sensor (), connected to the apparatus () and spaced out along the same; () of deriving shape, phase and amplitude parameters for each of the signals detected; () of separating the sets of signals detected in each sensor into respective subsets which are uniform in terms of pulse waveform; () of identifying the subsets of signals relating to partial discharges and classifying them; () of correlating the subsets relating to different sensors and similarly classified, in order to derive a pair of subsets of signals relating to the same discharge site (); () of selecting, for the pair of correlated subsets, at least one pair of homologous pulses () detected in different sensors in the same time interval; and () of calculating the distance between the discharge site () and the sensors, based on the selected pair of homologous pulses ().

A method for detecting, identifying and locating partial discharges occurring in a discharge site along an electric apparatus comprises the following steps: detecting (1) electrical signals in a detection station; attributing (2) to each detected signal a value of a phase parameter; deriving (3) for each signal at least one shape parameter and one amplitude parameter; separating (4) the set of signals detected into subsets that are homogeneous relative to the shape parameter; identifying (5) sub-sets related to partial discharges and cataloguing them; repeating the above steps in a plurality of detection stations positioned along the apparatus; correlating (7) the sub-sets of signals detected in different detection stations and catalogued similarly; selecting (8) as a function of the amplitude and shape parameters of a sub-set among the correlated ones and locating (9) the partial discharges related to said sub-sets at the detection station of the selected sub-set. Known methods have poor effectiveness and/or reliability, especially for cables whose length exceeds 1-2 km or, alternatively, they require an excessively complex and costly field implementation.

Method for detecting, identifying and locating partial discharges occurring in a discharge site along an electric apparatus

A method for measuring and processing data pertaining to an activity of partial electrical discharges taking place in a three-phase electric machine () powered with square wave voltage, said data comprising a plurality of discharge signals and a plurality of sets of three values (e, e, e) of power supply voltage of the machine measured in concurrence with a corresponding discharge signal, comprises the following steps: &#x2014;transforming each set (e, e, e) of three voltage values measured into a corresponding pair (e, e) of voltage values; &#x2014;deriving a phase angle value from each of said pairs (e, e) of voltage values; &#x2014;attributing to each discharge signal the corresponding phase value, to assess the measured discharge signals as a function of corresponding phase values. Prior art techniques for processing data pertaining to activity of partial electrical discharges taking place in three phase electric machines powered with square wave voltage provide for assessing the measured discharged signals as a time sequence of events, with no possibility to place them effectively in relation to the power supply voltages, this entailing that any subsequent statistical processing of the measured data will have little significance.

Method for processing data pertaining to an activity of partial electrical discharges

An instrument () and a method for measuring pulses of partial electrical discharges in an electrical system comprise data processing means () operatively associated both with an input stage (), able to receive an analogue signal () representing said pulses and to provide a digital representation of the entire wave form of the pulses, to receive said digital representation, extract the value of predetermined parameters relating to the wave form of the pulses and transfer to and output stage () a processed digital signal comprising said values, the processing means () being able to operate substantially in real time, i.e. with no need for a memory for the intermediate storage of the data. Known solutions within the field of the measurement of partial discharge pulses for diagnostic purposes provide for the use of peak detector instruments, which are not able to measure all information useful for a diagnosis of the electrical system, and oscilloscopes interacting with a computer, disadvantageous in terms of costs and of calculation efficiency.

Instrument and method for measuring partial electrical discharges in an electrical system

A method of analyzing partial discharge data collected from an electrical device includes collecting partial discharge data from a first electrical device belonging to a group of electrical devices. The group of electrical devices is at least partially defined by at least one electrical device classification. The method also includes generating a comparison of at least a portion of the partial discharge data collected from the first electrical device with at least a portion of the partial discharge data collected from at least one second electrical device. The at least one second electrical device is selected from the group of electrical devices that includes the first electrical device. The method further includes transmitting the results.

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Casalecchio di Reno, Italy

Gian Carlo Montanari