Abstract: An instrument (1) and a method for detecting partial electric discharges involve acquiring a discharge signal (10), for example picked up by a direct-measuring impedance device (7) through a broadband HF acquisition channel (18), and acquiring the discharge signal (10) in a narrowband LF acquisition channel (180) complying with regulations, using on the LF acquisition channel (180) a trigger controlled in slave mode by a trigger of the broadband HF acquisition channel (18); they also involve acquiring another discharge signal (32) picked up by an indirect-measuring impedance device (8) through a second narrowband LF acquisition channel (180A) and comparing digital signals (34, 34A) generated in the first and second LF acquisition channels (180, 180A), in order to generate a balanced digital signal (36) without components representative of common mode electrical signals present in the measuring circuit.

Abstract: A device for measuring the concentration of a gas dissolved in an electrical insulation oil comprises a measuring member (2), internally defining a measuring chamber (3) and a conduit (4) to access the measuring chamber (3), a membrane (6) permeable to gases, inserted inside the conduit (4) for insulating the measuring chamber (3) against the oil and allowing gas to pass from the oil to the measuring chamber (3), a sensor (20) located in the measuring chamber (3) for measuring the concentration of gas in the measuring chamber (3), and a reinforcing grid (8) positioned in the conduit (4) for preventing deformation of the membrane (6), where the grid (8) is located at a position adjacent to the membrane (6) on the side opposite to the measuring chamber (3), and has at least one through section (9, 10) for allowing the oil to exert pressure directly on the membrane (6).

Abstract: A method for locating partial discharges occurring at a discharge site (2) in an electric apparatus (3) with elongate geometry and generating corresponding electric pulses (4) propagating in opposite directions along the apparatus (3) from the discharge site (2) comprises the steps of detecting (11) the electric pulses (4) picked up by a first and a second sensor (5, 7), operatively connected to the apparatus (3) and spaced out along it, and generating corresponding electric signals representative of the waveform of the pulses (4), selecting (12) at least one pair of signals, detected in the consecutive sensors (5, 7), and representative of a pair of homologous pulses (4), 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 (4), at least one attenuation parameter, correlated with a quantity that is variable depending on the distance travelled by the pulses (4), calculating (13) the distance betwe

Abstract: A method for deriving the concentration of a gas dissolved in an electrical insulating oil (2) comprises the following steps:—preparing a membrane (5) permeable to the gas, interposed between a container (7) of the oil (2) and a measuring chamber (4) that receives a part of the gas through the membrane (5);—measuring the value of gas concentration in the measuring chamber (4);—deriving an estimated value of the concentration of the gas in the oil (2) as a function of the measured value,—the measuring step comprising taking at successive measuring instants a plurality of measurements of the values of gas concentration in the measuring chamber (4);—the deriving step comprising calculating the estimated value of gas concentration in the oil (2), at an instant selected from said measuring instants, according to a non-linear function of the values measured at the selected measuring instant and at one or more of the measuring instants preceding the one selected.

Abstract: 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.

Abstract: A method for locating partial discharges occurring at a discharge site (2) in an electric apparatus (3) with elongate geometry and generating corresponding electric pulses (4) propagating in opposite directions along the apparatus (3) from the discharge site (2) comprises the steps: (11) of detecting the pulses (4) picked up by a first and a second sensor (5, 7), connected to the apparatus (3) and spaced out along the same; (15) of deriving shape, phase and amplitude parameters for each of the signals detected; (17) of separating the sets of signals detected in each sensor into respective subsets which are uniform in terms of pulse waveform; (18) of identifying the subsets of signals relating to partial discharges and classifying them; (19) 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 (2); (12) of selecting, for the pair of correlated subsets, at least one pair of homologous pulses (4) det

Abstract: 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 sub sets 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.

Abstract: An apparatus (1) for measuring the loss factor of an insulator (2) for medium or high voltages, equipped with a tap adapter (3) forming a point for picking up an electrical signal (4), comprises a reference capacitor (9) having a first electrode (10), which can be connected to the tap adapter (3), and a second electrode (11); a first voltage detection module (12) operatively connected to the first electrode (10) of the reference capacitor (9) for detecting a signal representative of the voltage applied to the reference capacitor (9); a generator module connected to the first electrode (10) of the reference capacitor (9) in order to inject a direct electric current into the insulator.

Abstract: An apparatus (1) for measuring the loss factor of an insulator (2) for medium or high voltages, equipped with a tap adapter (3) forming a point for picking up an electrical signal (4), comprises: a reference capacitor (9) having a first electrode (10), which can be connected to the tap adapter, and a second electrode (11); a first voltage detection module (12) operatively connected to the first electrode (10) of the reference capacitor (9) for detecting a signal representative of the voltage applied to the reference capacitor (9); an active electronic device (13) connected to earth and to the second electrode (11) of the reference capacitor (9) and configured to keep the potential of the second electrode (11) at a predetermined reference value; a second voltage detection module (14) operatively connected to an output of the active electronic device (13) in order to detect a signal representative of the electric current that flows through the reference capacitor (9).

Abstract: An instrument (1) and a method for detecting partial electric discharges involve acquiring a discharge signal (10), for example picked up by a direct-measuring impedance device (7) through a broadband HF acquisition channel (18), and acquiring the discharge signal (10) in a narrowband LF acquisition channel (180) complying with regulations, using on the LF acquisition channel (180) a trigger controlled in slave mode by a trigger of the broadband HF acquisition channel (18); they also involve acquiring another discharge signal (32) picked up by an indirect-measuring impedance device (8) through a second narrowband LF acquisition channel (180A) and comparing digital signals (34, 34A) generated in the first and second LF acquisition channels (180, 180A), in order to generate a balanced digital signal (36) without components representative of common mode electrical signals present in the measuring circuit.

Abstract: An instrument (1) and a method for detecting partial electric discharges involve acquiring a discharge signal (10), for example picked up by a direct-measuring impedance device (7) through a broadband HF acquisition channel (18), and acquiring the discharge signal (10) in a narrowband LF acquisition channel (180) complying with regulations, using on the LF acquisition channel (180) a trigger controlled in slave mode by a trigger of the broad-band HF acquisition channel (18); they also involve acquiring another discharge signal (32) picked up by an indirect-measuring impedance device (8) through a second narrowband LF acquisition channel (180A) and comparing digital signals (34, 34A) generated in the first and second LF acquisition channels (180, 180A), in order to generate a balanced digital signal (36) without components represenative of common mode electrical signals present in the measuring circuit.

Abstract: A method for deriving the concentration of a gas dissolved in an electrical insulating oil (2) comprises the following steps:—preparing a membrane (5) permeable to the gas, interposed between a container (7) of the oil (2) and a measuring chamber (4) that receives a part of the gas through the membrane (5);—measuring the value of gas concentration in the measuring chamber (4);—deriving an estimated value of the concentration of the gas in the oil (2) as a function of the measured value,—the measuring step comprising taking at successive measuring instants a plurality of measurements of the values of gas concentration in the measuring chamber (4);—the deriving step comprising calculating the estimated value of gas concentration in the oil (2), at an instant selected from said measuring instants, according to a non-linear function of the values measured at the selected measuring instant and at one or more of the measuring instants preceding the one selected.

Abstract: A diagnostic method and apparatus for assessing the insulation condition of electrical equipment (3) insulated with oil (2). The method comprises the following steps: measuring the concentration of at least one gas dissolved in the insulating oil (2) of the electrical equipment (3); deriving at least one concentration parameter correlated with the gas concentration measured in a predetermined acquisition time interval; measuring electrical pulses relating to partial electrical discharges which occur in the electrical equipment (3) and which generate said pulses; deriving at least one discharge parameter correlated with the partial discharges measured substantially concurrently with the predetermined acquisition time interval; deriving a diagnostic indication about the insulation condition of the electrical equipment (3) as a function of the derived values of the concentration and discharge parameters.

Abstract: An instrument (1) for measuring the loss factor of an electrical apparatus (2) having an axially extending elongate geometry, in particular a medium voltage cable, comprises: at least a first and a second sensor (3A, 3B) connectable to the apparatus (2) in a first and a second measuring section (4A, 4B) axially spaced along the apparatus (2) by a predetermined quantity, respectively, and designed to measure respective values of the magnetic field generated outside the apparatus (2) by a load current flowing axially through the apparatus; a processing unit (5) designed to receive the magnetic field values measured by the sensors (3A, 3B) and programmed to derive from them a load loss value as a function of the difference between the measured magnetic field values.

Abstract: A device (1) for detecting and processing signals relating to partial electrical discharges in an electrical apparatus (2) powered by a square-wave (3) voltage modulated by a modulating wave (4) in such a way as to form an alternating voltage of predetermined frequency, comprises: a sensor (5) connectable to the apparatus (2) for detecting a discharge signal (6) representing the electrical pulses generated by the partial discharges; a processing unit (7) connected to the sensor (5) to receive the discharge signal (6) and derive the detection instants of each of the pulses detected with respect to a predetermined time reference, a synchronization module (8) designed to receive an electrical signal (9) representing the power supply voltage and equipped with a filter (10) configured for extracting from said power supply signal (9) a signal (11) representing the modulating wave (4), the processing unit (7) being configured for associating with the pulses detected the values of a phase parameter (f) representing t

Abstract: A method for measuring and processing data pertaining to an activity of partial electrical discharges taking place in a three-phase electric machine (1) powered with square wave voltage, said data comprising a plurality of discharge signals and a plurality of sets of three values (eu, ev, ew) of power supply voltage of the machine measured in concurrence with a corresponding discharge signal, comprises the following steps: —transforming each set (eu, ev, ew) of three voltage values measured into a corresponding pair (ed, eq) of voltage values; —deriving a phase angle value from each of said pairs (ed, eq) of voltage values; —attributing to each discharge signal the corresponding phase value, to assess the measured discharge signals as a function of corresponding phase values.

Abstract: An instrument (1) for detecting partial electric discharges in an electric apparatus comprises: an input stage (2) set up to receive a discharge signal (3) representative of one or more partial discharge pulses and a sync signal (4) representative of an alternating voltage applied to the electric apparatus; a data processing stage (6) connected both to the input stage (2) and to an output stage (5) for receiving the discharge signal (3) and the sync signal (4), and extracting substantially in real time for each pulse detected the value of an amplitude parameter (q), correlated with a pulse amplitude, and the value of a phase parameter (f), representative of the phase of the voltage applied to the electric apparatus concurrently with the pulse, and transferring to output a processed digital signal (7) comprising the values extracted.

Abstract: A method for locating partial discharges occurring at a discharge site (2) in an electric apparatus (3) with elongate geometry and generating corresponding electric pulses (4) propagating in opposite directions along the apparatus (3) from the discharge site (2) comprises the steps: (11) of detecting the pulses (4) picked up by a first and a second sensor (5, 7), connected to the apparatus (3) and spaced out along the same; (15) of deriving shape, phase and amplitude parameters for each of the signals detected; (17) of separating the sets of signals detected in each sensor into respective subsets which are uniform in terms of pulse waveform; (18) of identifying the subsets of signals relating to partial discharges and classifying them; (19) 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 (2); (12) of selecting, for the pair of correlated subsets, at least one pair of homologous pulses (4) det

Abstract: A method for locating partial discharges occurring at a discharge site (2) in an electric apparatus (3) with elongate geometry and generating corresponding electric pulses (4) propagating in opposite directions along the apparatus (3) from the discharge site (2) comprises the steps of detecting (11) the electric pulses (4) picked up by a first and a second sensor (5, 7), operatively connected to the apparatus (3) and spaced out along it, and generating corresponding electric signals representative of the waveform of the pulses (4), selecting (12) at least one pair of signals, detected in the consecutive sensors (5, 7), and representative of a pair of homologous pulses (4), 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 (4), at least one attenuation parameter, correlated with a quantity that is variable depending on the distance travelled by the pulses (4), calculating (13) the distance betwe

Abstract: An instrument (1) and a method for measuring pulses of partial electrical discharges in an electrical system comprise data processing means (5) operatively associated both with an input stage (2), able to receive an analogue signal (3) 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 (4) a processed digital signal comprising said values, the processing means (5) being able to operate substantially in real time, i.e. with no need for a memory for the intermediate storage of the data.