DD275540A1 - PART DISCHARGE SENSOR - Google Patents

Abstract

The partial discharge sensor is used in an on-site diagnosis of electrical equipment without their activation by detection of partial discharges (TE) for anomalous early detection of insulation damage and permanent health diagnosis as accidental protection. The detection of TE by means of various adapters, even in disturbed environment in one or two-pole galvanic connection to parts or metallic Gefaessen of electrical equipment. In this case, an antenna or the housing of the TE sensor acting as an antenna can also be used. The processing unit effects charge amplification and shaping of the detected TE signals with an extremely low-power arrangement of a plurality of complementary transistors by utilizing a short-term avalanche breakdown of a reverse-biased emitter-base path in the signal path. Fig. 4

Description

For this 7 pages drawings

Field of application of the invention

The invention relates to the field of partial discharge measurement in the on-site diagnosis of electrical equipment, such as transformers, generators, motors, switchgear including solid-insulated and SF ₆ switchgear, cable networks, etc., without activation of these objects. In addition to the cyclical or permanent diagnosis of the condition, this also provides possibilities for the early detection of anomalies and the triggering of shutdowns of endangered objects, if a disruptive breakdown is prevented.

Characteristic of the known technical solution

In addition to the classical and standardized partial discharge measurement technique (IEC publication 270 [1981]), a small probe and a more favorable useful-to-noise ratio are aimed for on-site diagnosis Klausen, A .: On-site surveillance of potential transformers by Means of DP measurement CIGRE symposium, Vienna 1987, Section 700-01) or the temporary interference components with electronic discriminator circuits to compensate (Lemke, E .: Diagnosis of electrical equipment on the basis of very broadband partial discharge measurements ELEKTRIE, Berlin 38 [1984] 10, pp 387-398) A 50 Hz test AC voltage based method for detecting internal TE pulses is described in DE-OS 27 21353. Disturbances, eg external discharges, which occur in the range of the maximum of the test voltage, are provided by special electronic means e Short-circuited suppressed and thus not used for the evaluation.

WP 253333 discloses an arrangement for suppressing the HF interference voltages superimposed on the partial discharge signals, which consists essentially of a push-pull transistor circuit with diodes and a controllable resistor between the two bases for generating a quiescent current. To the control electrode of the controllable resistor is via a

Separating capacitor and a rectifier circuit with optimum timing and basic level setting the output of a useful-Störsignal-mixture amplifying control amplifier and a decoupling diode of the control pulse so that when the active control signal, only the partial electrical discharge pulses are transmitted through the push-pull transistors.

DE-OS 3630026 discloses an ultrasonic sensor for the indication of TE from a partially flat formed, fixed in several curvatures and fixed to the specimen optical fiber loop which is coupled at one end with a monochrome light source and at the other end with a light sensor. The ultrasonic waves caused by TE cause elastic changes in the radii of curvature of the light guide, thus coupling and loss or modulation of the light, which is used for indication and evaluation.

DE-PS 3408256 discloses a measuring probe for detecting the electromagnetic radiation field resulting from the ignition of TE with frequency components well above 100 MHz by means of a broadband antenna which consists of a three-electrode system connected to one another via a compensation network. On the side facing the specimen, a frame-shaped compensation electrode is arranged between a measuring electrode and a reference-type housing-equipped reference electrode, and differential amplifiers are integrated within the reference electrode whose rise time is very small compared to the duration of the TE pulses and nanosecond lies. The arrangement of the electrodes results in a good straightening effect and by their interconnection increased interference signal reduction of Femfeldern.

The condition monitoring described above requires the constant readiness for operation of the TE probe. Since the troubled Störsignalunterdrückung can only be fully effective in potential-free operation (without mains connection), a cyclic replacement of internal batteries or their recharging is inevitable with permanent condition monitoring, so that in addition to the complex maintenance intermittent service interruptions can not be excluded.

Consequently, a second probe would have to be available for each measurement point to ensure redundancy if a critical error occurs at the moment of maintenance.

Also, the circuit complexity for the previously known TE probe (DD-WP 214461) is not insignificant, but their possible uses on the o. G. Scope of accidental damage.

Finally, for the purpose of permanent condition monitoring, the TE probe would have to be permanently installed on the object to be protected.

Problems arise in terms of ensuring accessibility for the purpose of battery replacement. In addition, size and weight of the known TE probe do not allow easy attachment to the object. For outdoor objects, the problem of climate protection is added. Finally, in view of selective fault detection, it would be desirable to make measurements at several vulnerable locations within electrical equipment (eg in the transformer, i.e. under oil). For this purpose, the previously known TE probe is not suitable because it can not be hermetically sealed.

Due to the required rapid transhipment of parasitic stray capacitances, the wideband amplifiers customary in the prior art for amplifying the high-frequency TE signals (<100 MHz) consciously require small working resistances (<100 ohms), with switching times in the nanosecond range and thus large operating currents (approximately 10 mA transistor) ), which hinders battery operation for a sufficient period of operation.

In classical rectifier circuits (including in avalanche diodes) the threshold is about 2 to 10% of the final control, so that only dynamic range of 1:50 to 1:10 can be achieved. The need for a fixed operating point adjustment in the classical rectifier by means of a voltage divider also increases the power consumption.

Object of the invention

It is an object of the invention to realize a TE sensor for TE diagnosis including TE anomaly early detection, as well as the accidental protection of high-quality electrical high-voltage equipment. The aim is:

- simplest circuit design,

- low number of components,

- feasibility as integrated circuit,

- low energy consumption,

- low weight,

- small dimensions,

- possibility of hermetic encapsulation,

high immunity to interference,

- high dynamics of the modulation without measuring range switching,

- simple adaptation options on the test object (if necessary implementation)

Reactivity only to short-time pulses in the nanosecond time range,

- TE signal detection on metal surfaces at a distance of the measuring points of only 10cm.

The above-mentioned objectives are in part directly linked with each other and complement each other.

Explanation of the essence of the invention

Based on the above objective, the task of receiving TE signals by means of a pickup from the test object while reducing the noise level and in a processing unit to form so that the output signals at an elevated level and thus reduced risk of further interference of subsequent signal processing in the center ( eg control room) can be supplied.

According to the invention the object is achieved in that the transducer is a respective test object adapted adapter, which is connected via a signal line and two charge storage capacitors each with the interconnected by Hochohmwiderstand bases of two complementary bipolar transistors whose emitters each to a pole

an operating voltage and the collectors are connected to each other and are connected via a respective coupling capacitor and a mutually complementary poled in the reverse direction emitter-base path and a respective charging capacitor to one pole of the operating voltage. In addition, each charging capacitor terminal is preferably connected to the base per mutually complementarily constructed emitter follower, wherein in each case the connection point of the coupling capacitor and the emitter-base path are respectively connected via clamping resistors to the pole of the operating voltage to which the collector of the associated emitter follower is located. Of the two in the emitter branches working resistances amplified and stretched TE signals are coupled by means of series capacitors to an output jack to which the signal processing stage, preferably connected via an output signal line.

If the test object has a metallic vessel, it is advantageous to pick up partial discharge signals at exposed locations of the wall, wherein according to the invention it is provided that the adapter consists of two contact tips with a distance determining the active measuring zone of a metallic test sample vessel.

Another possibility of TE signal detection is that the adapter is in a single-pole contact with the test object and the conductive housing of the sensor forms an antenna.

An expedient embodiment according to the invention provides that the single-pole contacting takes place in the case of ferromagnetic test vessel vessels by means of a magnet.

However, it is expedient in some applications that the electrically conductive housing of the sensor is electrically and mechanically connected to the housing of the test object and a preferably disc-shaped antenna is arranged as the opposite pole.

In particular, for the latter arrangement is provided to increase the useful-to-noise ratio according to the invention that is connected from the signal line to the sensor housing a short-circuited waveguide with a wave transit time of less than 100 ns.

It is possible that the waveguide consists of a coaxial cable whose inner conductor is connected on the input side to the signal line and the output side to the metallic housing of the sensor or that a parallel strip line is connected accordingly. Even by means of a pulse transformer, interference pulses of over 100 ns duration can be separated from the short TE signals and thus improve the signal-to-noise ratio.

A variant of a pulse transformer provides that the adapter has two inputs, which are connected to the beginning and end of the inner or outer conductor of a coaxial line, preferably wound on a Manifer pot core whose outer or inner conductor at one end via the signal line to the two Charge storage capacitors and connected at the other end to the ground of the circuit arrangement.

Instead of a battery power supply or buffering the same, it is also possible to feed via the output signal from the control room a supply current, according to the invention a contact of the output jack is connected via a resistor to the positive and the other contact via a resistor to the negative operating voltage line and at the end the output signal line in the control room chokes a power supply is connected. To avoid oscillation tendencies and unbalanced control is provided that a low-inductance smoothing capacitor is connected via the connection points of the transistor emitter with the operating voltage potentials.

To increase the detection limit for the TE sensor, it is possible according to the invention that between the signal line and the bases of the two complementary bipolar transistors an equally constructed second complementary transistor arrangement with charge storage capacitors is inserted as a precursor.

One possible and advantageous in some applications configuration of the invention provides that the transducer consists of an active broadband antenna, preferably from the known three-electrode system with fast differential amplifiers.

The evaluation in the center is expediently carried out with digital signals, it is expedient that instead of the emitter follower as a voltage follower connected OP amplifiers are arranged, whose outputs are connected to a unipolar pulse train generating arrangement.

The TE signals of a high-voltage potential TE sensor to the center is preferably carried out in that the output jack is connected to the modulation input of a downstream light emitter or laser assembly coupled via optical fiber or a focused beam with a signal processing stage upstream light receiver with demodulator is.

A simple analog signal evaluation and assessment of critical isolation errors provides that in the signal processing stage, a measured value is formed, which corresponds to the mean value of the square of the TE impulse charges. Appropriate capacitive coupling of the signal processing stage requires zero level clamping, in which an OP amplifier with its noninverting input to reference potential and with its inverting input via a high pass capacitance at the output of the processing unit, via a high pass cross resistance to reference potential, via a diode in parallel with a resistor to the Output of the op-amp and are connected to the input of an integrator.

The integration forms a signal level corresponding to the mean square value of the TE impulse charge. In this case, an economic variant provides that the integrator consists of a resistor-capacitor resistor series circuit, wherein the output signal is tapped off via the capacitor, or, that a switched as an active integrator OP amplifier instead of or with the resistor-capacitor resistor Row circuit are arranged. The combination of the resistor-capacitor resistor series circuit also prevents, due to their low-pass behavior considered by the output jack, from influencing the TE sensor by external high-frequency interference signals which can be picked up by the signal line from the environment as a result of the antenna effect.

embodiment

In the following embodiment, the invention will be explained in more detail with reference to seven figures. Show it:

Fig. 1: The basic principle of TE sensor technology

Fig. 2: The adaptation by means of magnet and use of the probe housing as an antenna

Fig. 3: The adaptation with mechanical attachment and simultaneous electrical contacting of the probe housing on

Metal housing of the test object and connection of a disk-shaped radiator to the signal line

Fig.4: A total flow diagram of the TE sensor

Fig. 5: A circuit example for analog pulse conditioning

Fig. 6: Two variants of a pulse transformer

Fig. 7: A circuit example for averaging the square of the TE pulse charges

Fig. 1 shows the basic principle of the partial discharge sensor technique. The partial discharges TE radiated by the different test objects MO can be applied in a variety of different ways, i.a. also removed at the metallic conductive vessels MG by means of adapters AD, amplified and shaped in the processing unit VE and evaluated after transmission to the central unit SV.

In the simplest case, the adapter AD is realized by the metallic vessel MG of the test object PO to the part itself, wherein as an active measuring zone, the area between the metallic contacted tapping points MP ₁ ; MP ₂ is used. The distance MPi-MP ₂ determines the threshold. It can be reduced to less than 10 cm.

Another possibility of TE signal detection is the single-pole contact with the test object, in which case the opposite pole is realized by the housing of the sensor itself, which acts as a radiator (antenna) for the rapid electromagnetic compensation processes in TE signals. For single-pole contacting, the use of magnetic clamps HM is also expedient for iron vessels MG (FIG. 2).

On the other hand, it is also possible to use an inverse arrangement, i. H. the metallic housing SG of the sensor is electrically and mechanically connected to the test object housing MG, and the opposite pole is by an additional radiator SR (antenna), the z. B. disk-shaped, realized (Figure 3).

Preferably, for the latter arrangement, a coaxial cable KL is used in conjunction with the adapter to simulate a fictitious short circuit for signals lasting more than a few tens ns. Whose inner conductor is the input side to the signal line SL and the output side connected to the metallic housing SG of the sensor (Figure 4).

The outer conductor of the cable KL is connected on both sides with the sensor housing SG. The optimal length of the cable KL is between 10 and 50cm. With regard to the universal use, it is expedient to completely integrate this RF cable KLaIs part of the adapter into the circuit (Figure 4). In principle, instead of the coaxial cable KL also modified waveguides can be used, such. B. pulse transformer or parallel stripline.

Fig. 6 shows schematically the possibility to wrap a coaxial line KL on a manifold shell core or by a ring star MK and interconnect as a pulse transformer.

In variant A, the two inputs MP1; MP2 is connected to the beginning and end of the inner conductor IL1 of the coaxial line KL, while the beginning or end of the outer conductor ALI via the signal line SL with the charge storage capacitors C _S i; Cs ₂ ) and the end or beginning of the outer conductor AL 1 is connected to the ground of the circuit arrangement.

In variant B, on the other hand, the two inputs MPI; MP 2 is connected to the outer conductor AL2 of the beginning and end of the coaxial line KL, while the inner conductor IL2 are connected to the signal line SL and ground.

This pulse transformer with a manifold shell core MK and few turns of the coaxial line KL represents a space-saving arrangement, which causes a sharp separation of disturbing pulses.

For signal amplification in the nanosecond time range, concepts are used in conventional circuit technology whose power consumption is in the range of a few 10 mA due to the required rapid transhipment of parasitic stray capacitances (operating voltage about 10 V). In addition, considerable expenditure is required for the rectification of low-amplitude nanosecond pulses (threshold 10 mV) coupled with great dynamics (modulation up to 5 V, for example) up to 5 V in classical circuit technology, as a result of which the power consumption also increases considerably.

An unexpected in the field of nanosecond pulse technology effect with respect to lowest power consumption (<1 mA) and high dynamics is achieved by the inventive arrangement in which a counter circuit of a bipolar transistor T ₂ npn-type with a pnp transistor T ₁ in the Way, that the collectors of both transistors directly and the base of each transistor T ₁ ; T _{2 are} connected via a high-impedance resistor Rb in MOhm range (Figure 4). The emitter of the pnp transistor T ₁ is connected to the positive operating voltage pole (+) and the emitter of the npn transistor T ₂ to the negative operating voltage pole (-). The input signal line SL is connected to the base of the transistors T ₁ via the charge storage capacitors C _S1 and Cs ₂ whose capacitance is in the range of a few 1OpF; T ₂ connected. The connection point of the collectors of both transistors T ₁ , T ₂ is connected on the one hand via a coupling capacitor Ck ₁ in the range of less than 1OnF with a clamping resistor R _K1 in the order of 50 kOhm, which rests with its other terminal to the negative operating voltage (-) , The connection point of coupling capacitor Cm and resistor R <1 is connected to the emitter of a pnp transistor T ₃ whose base is connected via a charging capacitor C _{L1 of} the capacity of the order of 10OpF to the positive operating voltage (+). At the connection point of the charging capacitor C _L , and the base of T3, the base of a pnp transistor T _{4 is connected} in collector circuit with the working resistor R _A1 .

In an analogous manner, a second measuring branch is realized, consisting of the corresponding components C _K2 , Rk ₂ , Cl ₂ , Ra ₂ and the npn transistors T ₅ and T ₆ . The values of the resistors Ra ₁ and Ra ₂ are of the order of 10 kOhm.

The crossover frequency of all transistors is above 500 MHz.

At the connection point of transistor T ₄ and resistor R _A1 and transistor T ₈ and resistor Ra ₂ , a series capacitor Cm and Cr _{2 is} connected in each case, whose mating terminals are connected together. At the connection point of the components C _n ,, Rr ₂ , the coaxial output jack K _{3 is} connected, on the one hand, the signal propagation to the subsequent signal processing stage SV and optionally a supply of the operating voltage of about 8 to 10V is ensured by then with a contact via a Resistor Rr, the size of about 1 kOhm, connected to the positive (+), and with the other contact via the isolating resistor Rt to the negative (-) operating voltage line.

At the end of the output signal line connected to the output signal socket КЗ in the control room, the signal processing stage SV is connected via a capacitor and the power supply via a choke. The outer conductor of the output signal line is clamped there to reference potential (ground).

The smoothing capacitor CG is designed as a ceramic disk capacitor and has a capacity of about 10OnF. It is to avoid oscillation tendencies and unbalanced controls in short-term pulses directly to the connection point of the emitter of transistor T ₁ with the negative operating voltage (-) and to the connection point of the emitter of transistor T ₂ with the positive operating voltage (+ (connected, wherein the supply line on both sides of the capacitor Cq is limited to less than 2cm

 The basic mode of operation of the circuit according to FIG. 4 is the following:

By means of the signal adapter AD in conjunction with the coaxial cable KL, the maximum duration of the TE signals detectable on the test sample vessel MG is limited in such a way that the highest measuring sensitivity is achieved with pulse rise times in the nanosecond time range. This purpose is fulfilled in particular by the short-circuit line KL, unless a fictitious short circuit for long-term signals already exists due to the contacting with the metallic vessel MG of the test object. As a result, the useful-interference signal distance can be significantly improved thereby, since usual interfering signals u.a. are characterized by rise times in the range of a few 100 to 1000 ns and are thus considerably longer than the o. g. Value of a few ns for maximum measurement sensitivity.

Due to the counter- _{circuit of} the transistors Τ _Ί and T ₂ with simultaneous connection of the bases of these transistors via a high-ohmic resistance (^ 1 Mohm), this transistor arrangement is in a sense in the "snooze" state, ie the power consumption is far below 1 mA Short pulse of a few ns duration whose voltage amplitude exceeds about 1 mV, with positive polarity of the pulse, a charge fraction from the storage capacitor C _S i and injected into the base of the transistor T _1. After transient charge storage in the transistor Ti is after the input pulse almost decayed , a collector current pulse is triggered in the transistor Ti The transistor T ₂ remains in the considered positive polarity in the "snooze" state, that is, no additional current flow through transistor T _{2 is} excited. Accordingly, at the connection point of the collectors of the transistors T ₁ and T _2, a voltage change, which essentially results from the discharge of the storage capacitor C _u , is given by the current path from the collector of the transistor T ₁ via the coupling capacitor Сщ and a limited avalanche breakdown of the emitter base. Distance of the transistor T ₃ to the charging capacitor C _L1 . In contrast, the reverse-biased transistor T ₅ remains in the considered polarity still in the blocking state. Corresponding to the current amplification and thus also the charge amplification of transistor Ti, a signal amplitude which exceeds the input signal is reached at the charging capacitor C _L1 , above all the duration of the signal at the charging capacitor C _Lt as a result of the termination of the avalanche breakdown and restarting blocking phase of transistor T ₃ is greatly stretched. This results in a rapidly rising and almost linearly sloping signal edge, ie it is a triangular pulse-won, which includes in its area the square value of the pulse charge. This characteristic is advantageously suitable for alarming a critical TE intensity in the sense of anomaly early detection.

Analogous conditions exist with opposite polarity of the input signal. In this case, the transistor T ₂ becomes active and transistor Ts suffers the limited avalanche breakdown while transistor T ₃ remains in the off state. When using transistors with a crossover frequency of over 500MHz, this proportional to the input signal memory effect is detectable down to the sub-nanosecond time range. It should be noted that this circuit arrangement according to the invention differs substantially from the "classical broadband amplifier", in which the working resistances are intentionally kept small in contrast to the present circuit (order of magnitude <100 ohms with switching times in the nanosecond range) and also the operating current of each transistor in the range of about 10mA The peak value storage according to the invention with transistors T ₃ and T _{s also} differs from conventional circuit arrangements: a rectifier effect already occurs at a voltage swing of only 10 mV, the two transistors used with a crossover frequency of more than 500 MHz even with switching times of a few ns On the other hand, in conventional rectifier circuits (including avalanche diodes), the threshold increases to 10 to 50 times, so that instead of a dynamic range of 1:50 0 only values from 1:50 to 1:10 can be reached at the given operating voltage of U ₈ = S 10V. The physical effect is based on the avalanche breakdown of the reverse-biased emitter-base path of transistors T ₃ ; T ₆ . It is particularly advantageous that no fixed bias must be set by means of a voltage divider. In contrast, in the case of classic rectifier circuits, an operating point setting is only possible on the one hand by voltage dividers, which increases the power consumption of the circuit. In addition, this measure is effective only when a diode current is excited, so that the blocking characteristic deteriorates.

Due to the simplicity of the circuit arrangement, in particular by the small number of components, the sensor can also be listed in integrated circuit technology. In addition, a hermetic encapsulation is provided so that the sensor can be installed not only outside but also inside electrical equipment (e.g., under oil). This results in a further improvement of the signal-to-noise ratio, since, on the one hand, the TE signals no longer have to penetrate the metallic encapsulation with corresponding attenuation and, on the other hand, this encapsulation as Faraday cage significantly attenuates the interference signals in the interior. By mounting several sensors in high-quality equipment (eg transformers), a multi-position measurement can also be advantageous for fault localization.

The smallness of the sensor is also beneficial for the pinpoint localization of TE-damaged bar windings of large motors and generators as evidenced by experimental studies.

It should be noted that the sensor can of course also be operated with internal battery, with a service life of at least one month can be achieved. This period of time seems sufficient to allow a damaged resource to remain in service for a period of time until a replacement unit is obtained. Due to permanent condition monitoring, total failure with all consequential damage can be avoided.

If an increase in the detection limit for the TE detection is desired, a circuit expansion by a pre-stage, which is analogous to the input circuit acc. _{4 is} realized with the components C ₃₁ , Csz, Rg, T ₁ and T ₂ . The circuit arrangement according to the invention can also be combined with an active broadband antenna as a pickup. As active broadband antenna is preferably the known three-electrode system with differential amplifier arrangement. For further signal processing in the control center, the digital technology is available. For this purpose, it is initially advisable to use an analog pulse supply when using circuit components of the TE sensor. An embodiment is shown in FIG. 5. This circuit arrangement, in which instead of the emitter follower T ₄ ; T _{8 are used} as a voltage follower switched operational amplifier, generated from bipolar needle pulses unipolar triangular pulses, which allow by means of a threshold trigger in a simple manner, an amplitude-time conversion and thus digitization.

If the entire partial discharge sensor is battery-powered to high-voltage potential, the transmission of the amplified and shaped TE signals to the evaluation devices is preferably to be carried out by means of focused light or laser beam or via high-voltage-resistant optical fiber cable. In this case, the partial discharge sensor according to FIG. 5 is connected with its signal output K1 to a modulation input of a light transmitter, not shown, which is likewise at high-voltage potential. Partial discharge sensor and light emitter can then preferably also be arranged in the interior of encapsulated, oil or Schutzgasgefüllter electrical equipment at high voltage potential, directly on the possible origin of partial discharges.

Fig. 7 shows a simple analog circuit arrangement for obtaining the mean square value from the unipolar triangular pulses as supplied from the circuit arrangement according to Fig. 5 to the output socket K1. The evaluation of this mean square value is a good and cheap alternative to the digital evaluation and, in deviation from the applicable standards (IEC270), allows a better assessment of a critical insulation error, since large TE pulses are particularly emphasized by the square value and also by averaging a dense sequence of TE pulses also lead to a high output signal.

The circuit arrangement preferably consists of two OP amplifier stages, which via a high-pass C ₁ ; R _{1 are connected} to the output socket K1 of FIG. The decoupling via the high-pass capacitor C _t prevents lower-frequency noise or operating point displacements of the upstream stage from leading to the displacement of the output signal level and thus to the distortion of the measured value. The time constant of the high pass C ₁ * R ₁ is about 1 ms. The first stage, with the diode D1 and the output resistor R2 in the feedback branch of the O PV strong rs, causes a clamping of the zero level, which would otherwise shift in dependence on the pulse train. The second OP stage represents an active integrator whose integration capacitor C ₁ located in the feedback branch forms a time constant Ci * R ₃ with the series resistor R3 about 10 ms and with its adjustable parallel resistor R ₄ a time constant C * R ₄ about 50 ms.

The signal level thus formed corresponds to the mean square value of the TE pulse charges.

The output side resistor-capacitor resistor series circuit, in which the output jack K2 is connected via the capacitor, is another passive integration member that can take over the function of the active integrator with appropriate dimensioning, so that the second operating stage in a economic variant can be omitted. In addition, this passive integrator prevents due to the low-pass behavior influencing the TE sensor by external high-frequency noise, which could be coupled due to the antenna effect on the output signal line from the environment in the output jack K2.

Claims (20)

1. Partial discharge sensor, in particular for on-site diagnosis, the anomaly-early detection and the accidental protection of electrical equipment, without the activation, consisting of a pickup for partial discharge signals and a processing unit, characterized in that the pickup adapted to the respective test object adapter (AD) which is connected via a signal line (SL) and two charge storage capacitors (Csi; Cs ₂ ) to the bases of two complementary bipolar transistors (T1; T2) interconnected by high resistance (Rb) so that their emitters are connected to one pole an operating voltage (+; -) are located and whose collectors are connected to each other and each via a coupling capacitor (C _K1 , Ck ₂ ), each one complementary polarity reverse-biased emitter-base path (T3, T5) and a respective charging capacitor (C _L1 , C _L2 ) are connected to one pole of the operating voltage that also each charging capacitor terminal (C _L1 C _L2 ), preferably with the base per each emitter follower (T4; T6), that in each case the connection point of coupling capacitor (C _K i; C < ₂ ) and the emitter-base path (T3; T5) in each case via clamping resistors (R <i;Rk2>) is connected to the pole of the operating voltage, on which also the collector of the associated emitter follower (T4, T6) is located and that of the two in the emitter branches lying working resistances (R _A1 , R _A2 ) each series capacitors (C _R1 , C _R2 ) the amplified and stretched TE signals to an output jack (КЗ) decouple, at which the signal processing stage (SV), preferably connected via an output signal line. 2. Partial discharge sensor according to claim 1, characterized in that the adapter (AD) consists of two contact tips (MP ₁ , MP ₂ ) with a the active measuring zone of a metallic Prüflingsgefäßes (MG) defining distance. Partial discharge sensor according to Claim 1, characterized in that the adapter (AD) consists of a single-pole contact with the test object (PO) and the conductive housing (SG) of the sensor forms an antenna. 4. Partial discharge sensor according to claim 3, characterized in that the unipolar contact in ferromagnetic Prüflingsgefäßen (MG) by means of a magnet (HM). 5. Partial discharge sensor according to claim 1, characterized in that the electrically conductive housing (SG) of the sensor is electrically and mechanically connected to the housing (MG) of the test object (PO) and is arranged as an antipode, a preferably disc-shaped antenna (SR). 6. partial discharge sensor according to claim 1 and 5, characterized in that from the signal line (SL) to the sensor housing (SG) a short-circuited waveguide with a wave transit time of less than 100ns is connected. 7. Partial discharge sensor according to claim 6, characterized in that the waveguide consists of a coaxial cable (KL) whose inner conductor is connected on the input side to the signal line (SL) and the output side to the metallic housing (SG) of the sensor. 8. Partial discharge sensor according to claim 6, characterized in that the waveguide consists of a parallel stripline. 9. partial discharge sensor according to claim 6, characterized in that instead of the waveguide, a pulse transformer is used. 10. partial discharge sensor according to claim 1,2 and 9, characterized in that the adapter (AD) has two inputs (MP 1; MP2), with the beginning and end of the inner (IL1) or outer conductor (AL2) one, preferably on a shell core (MK) wound coaxial line are connected, the outer (AL 1) and inner conductor (IL2) at one end via the signal line (SL) to the two charge storage capacitors (C _S i C ₃₂ ) and at the other end connected to the ground of the circuit arrangement. 11. Partial discharge sensor according to claim 1, characterized in that a contact of the output socket (КЗ) of the processing unit (VE) via a resistor (R _R ) with the positive (+) and the other contact of the output socket (КЗ) via a separation resistor (R _T ) is connected to the negative (-) operating voltage line, wherein at the end of the output signal line in the control room next to the signal processing stage (SV) choked a power supply is connected. 12. Partial discharge sensor according to claim 1, characterized in that a low-inductance smoothing capacitor (C _G ) via the connection points of the transistor emitter (T 1, T2) with the operating voltage potentials (+, -) is connected. 13. Partial discharge sensor according to claim 1, characterized in that between the signal line (SL) and the bases of the two complementary bipolar transistors (T1, T2) an equally constructed second complementary transistor arrangement with charge storage capacitors is inserted as a precursor. 14. Partial discharge sensor according to claim 1, characterized in that the transducer consists of an active broadband antenna, preferably from the known three-electrode system with fast differential amplifiers. 15. Partial discharge sensor according to claim 1, characterized in that arranged in place of the emitter follower (T4, T6) as a voltage follower connected OP amplifiers whose outputs are connected to a unipolar pulse train generating arrangement. 16. Partial discharge sensor according to claim 1 and 15, characterized in that the output socket (K 1) is connected to the modulation input of a downstream light emitter or laser array coupled via optical fiber or a focused beam to one of the signal processing stage (SV) upstream light receiver with demodulator is. 17. Partial discharge sensor according to claim 1 and 15, characterized in that in the signal processing stage (SV), a measured value is formed, which corresponds to the mean value of the square of the TE impulse charges. 18. Partial discharge sensor according to claim 1,15 and 17, characterized in that an OP amplifier with its non-inverting input (+) to reference potential (U _B o) and with its inverting input (-) via a Hochpaßkapazität (C ₁ ) at the output (K 1) of the processing unit (VE), connected via a high-pass filter resistor to reference potential (U _B _), via a diode (D 1) in parallel with a resistor (R 2) to the output of the OP amplifier and to the input of an integrator are. 19. Partial discharge sensor according to claim 18, characterized in that the integrator consists of a resistor-capacitor resistor series circuit, wherein the output signal (K2) is tapped off across the capacitor. 20. Partial discharge sensor according to claim 18 and 19, characterized in that an active integrator connected to the OP amplifier instead of or with the resistor-capacitor resistor series circuit are arranged.