Apparatus for monitoring power capacitors and adapter for such apparatus

Abstract

The invention relates to a device for monitoring a power capacitor, wherein the power capacitor has a housing, a housing interior of which can be closed gas-tight at at least one housing opening, the device comprising at least one sensor device which emits a signal depending on the gas pressure in the housing and an adapter which mechanically connects the sensor device with the housing at the housing opening and fluidically connects the sensor device with the housing interior, wherein the adapter has a columnar adapter body which is divided into a plurality of longitudinal sections which are functional and a sleeve which extends over the plurality of longitudinal sections for fluidic connection, wherein a first longitudinal section of the adapter body closes the sleeve in a plane perpendicular to a longitudinal axis of the adapter body and fluidically connects with the housing interior in at least one plane parallel to the longitudinal axis, the first longitudinal section being arranged in the region of the housing opening after the connection of the adapter with the housing.

Description

TECHNICAL FIELD

[0001] The invention relates to a device for monitoring a power capacitor, wherein an adapter is used to connect a sensor device to a housing of the power capacitor in order to ensure that a gas pressure in the interior of the housing of the power capacitor is reliably detected by the sensor device. The invention also relates to an adapter which is designed for such a device. BACKGROUND

[0002] Power capacitors are used in the drive train of electrically driven rail vehicles and in particular in the converter of such a drive train, for example to assume the function of an intermediate circuit capacitor. Typically, a direct voltage of more than 1 kV is present on the intermediate circuit capacitor of a direct voltage intermediate circuit.

[0003] Such power capacitors are usually designed as thin-film capacitors having a dielectric made of a plastic material, such as polypropylene or polyester. In addition to short-circuit fault conditions which can be identified by appropriate monitoring of the circuit, fault conditions of the power capacitor can also arise as a result of an aging process of the metallization layer of the dielectric. Here, corrosion of the metallization layer, which is made of, for example, aluminum or zinc, leads to increased electro-thermal losses during the operating time of the power capacitor, so that the self-healing capability of the fault location of the metallization layer is limited. The loss of this self-healing capability can lead to a melting and pyrolysis of the dielectric, in the case of which gaseous hydrocarbons are produced which, when in contact with the oxygen in the external air, can form an explosive environment. Therefore, the power capacitor should additionally be monitored in terms of fault conditions in which pyrolysis gases are formed in excess in the housing in order to be able to prevent the release of the pyrolysis gases as a result of a burst of the housing, for example caused by an increased gas pressure, by appropriate measures.

[0004] In order to monitor this fault condition, the power capacitor or its housing can be specially designed and the monitoring device can be adjusted accordingly, as described, for example, in the earlier international patent application WO 2017 / 028992 A1. There, a targeted volume change of the gastight housing of the power capacitor as a result of an increase in the gas pressure in the interior of the housing is used to detect such a fault condition.

[0005] Such monitoring of the power capacitors has not been carried out up to now in the drive trains of older rail vehicles or rail vehicles which have been in operation for many years. These power capacitors were also not prepared for such monitoring. But since the typical operating time of a rail vehicle is up to thirty years, it is also important for the safe operation of the rail vehicle to be able to monitor the condition of the installed power capacitors. However, it should be avoided here to replace the power capacitors by power capacitors specially prepared for monitoring, since this leads to high costs and the replacement of a drive train component which can function completely normally. SUMMARY

[0006] Thus, the technical problem to be solved by the present application is to enable reliable monitoring of power capacitors which are not prepared for this purpose.

[0007] This technical problem is solved by the device according to the present application and by the adapter according to the present application. The extended design is given in the description.

[0008] The device for monitoring a power capacitor according to the present application comprises at least one sensor device and an adapter, wherein the power capacitor has a housing, the interior of which can be closed gas-tight at at least one housing opening, the sensor device emits a signal depending on the gas pressure in the housing, the adapter mechanically connects the sensor device with the housing at the housing opening and fluidically connects with the interior of the housing, wherein the adapter has a columnar adapter body which is divided into functional longitudinal sections and a sleeve for fluidic connection which extends over the longitudinal sections, wherein a first longitudinal section of the adapter body closes the sleeve in a plane perpendicular to the longitudinal axis of the adapter body and fluidically connects with the interior of the housing in at least one plane parallel to the longitudinal axis, the first longitudinal section being arranged in the region of the housing opening behind the adapter and the housing.

[0009] Power capacitors, for example power capacitors which have been used in converters of rail vehicles for many years, usually have a columnar housing which has a circular or prismatic cross section. The housing is made of gas-tight welded aluminum or fine steel sheet, whereby the housing has a cup-shaped basic shape. One or more metallized foil windings are arranged in the housing, which windings are electrically connected with electrical terminals arranged on the housing bottom by means of copper strands or copper strips. The housing is closed gas-tight with a housing cover, for example made of the same material as the housing, again by welding. The housing cover or other housing walls usually have a smaller closable housing opening for introducing a filling material into the interior of the housing when manufacturing the power capacitor. For example, a hardened casting compound is used as filling material, which serves both for mechanical stabilization and for electrical insulation of the foil windings with respect to the metal housing. The housing opening usually has an internal thread, into which a corresponding closure cap is screwed in order to close the housing again gas-tight.

[0010] Such a housing opening is basically suitable for installing a sensor device instead of the closure cap with which the gas pressure in the interior of the housing of the power capacitor is monitored. For example, a known pressure switch for industrial applications is suitable as sensor device. The pressure switch usually has a columnar body which has openings at its longitudinal ends, through which openings a sensor, for example a membrane, is applied to the pressure of a fluid, for example a gas.

[0011] However, it is disadvantageous that the installation of such a pressure switch as a sensor device on the housing opening cannot ensure that the opening of the pressure switch is not at least partially closed by the potting compound located in the region of the housing opening, so that a change in the gas pressure in the housing cannot be detected by the sensor due to the lack of a fluid connection of the sensor to the environment inside the housing. A mechanical removal of the potting compound in this region can eliminate this problem, but should be dispensed with in order to ensure the operational reliability of the power capacitor.

[0012] According to the application, therefore, an adapter is provided in the device, which both establishes a mechanical connection of the sensor device to the housing opening of the housing and a reliable fluid connection of the sensor device to the interior of the housing. Here, a sleeve extending on the adapter body is used for the fluid connection, which adapter body is divided into a plurality of longitudinal sections. In order to prevent the sleeve from being closed by the potting compound when the adapter is installed on the housing opening, as described above, the sleeve is closed in a plane extending perpendicular to the longitudinal axis of the adapter body in a first longitudinal section of the adapter body, which is used for the fluid connection to the interior of the housing.

[0013] To this end, the adapter body can be embodied, for example, such that the plurality of longitudinal sections are arranged along a central longitudinal axis of the columnar adapter body and the sleeve extends centrally and with a determined uniform diameter along the longitudinal axis in the adapter body. The adapter body is mechanically connected to the capacitor housing at a first end thereof, at which the sleeve is closed by a portion of the adapter body arranged in a plane perpendicular to the longitudinal axis. When the adapter is installed on the housing opening or the first longitudinal section of the adapter body is arranged in the region of the housing opening, it is thereby advantageously avoided that the sleeve comes into direct contact with the filling material or potting compound and can be closed by it.

[0014] The fluid connection of the sleeve to the environment inside the housing is established, for example, by one or more adapter openings arranged in one or more planes parallel to the longitudinal axis of the adapter body and at a distance from the portion of the adapter body used for closing in the perpendicular plane. If the first longitudinal section has a circular cross section, a plurality of adapter openings are preferably distributed over the circumference of this longitudinal section and are designed, for example, as uniformly diametrical holes. If the cross section of the first longitudinal section has a prismatic cross section with a plurality of flat sides, the adapter openings can be distributed in the same manner, wherein, for example, an adapter opening is arranged on each side. As an alternative to uniformly diametrical holes, the adapter openings can also each have a rectangular cross section tapering towards the sleeve, for example. The longitudinal axis of the adapter openings is preferably oriented perpendicular to the longitudinal axis of the sleeve, but can alternatively also have a determined angle with respect to the longitudinal axis of the sleeve and be oriented, for example, from the sleeve in the direction of the interior of the housing.

[0015] According to one design variant of the device, a second longitudinal section of the adapter body, which is connected to the first longitudinal section, has an outer thread which is compatible with an inner thread of the housing opening, said second longitudinal section being intended for a mechanical connection with the housing.

[0016] Viewed in the direction of the longitudinal axis of the columnar adapter body, the second longitudinal section, which can also be referred to as the outer thread section, is thus arranged below the first longitudinal section. The diameter of the second longitudinal section and its outer thread are designed to be compatible with the diameter of the housing opening of the power capacitor housing or its inner thread, and thus enable a permanent threaded connection or a mechanical connection of the adapter with the housing. For example, the housing opening of the known power capacitor described above has a 1 / 2" inner thread, and the second longitudinal section accordingly has a 1 / 2" outer thread. The length of this outer thread in the direction of the longitudinal axis is for example essentially equal to the corresponding length of the inner thread of the housing opening. However, in particular, the outer thread of the second longitudinal section can also have a shorter length, if this shorter length is sufficient for a secure mechanical connection of the adapter with the housing of the power capacitor.

[0017] According to another design variant of the device based on the design variant described above, the outer diameter of the first longitudinal section is smaller than the outer diameter of the second longitudinal section.

[0018] In particular if, as described above, the length of the outer thread of the second longitudinal section is smaller than the length of the inner thread of the housing opening, after mounting the adapter on the housing opening, the adapter opening of the first longitudinal section is arranged partially or preferably completely within the housing opening or in the region of the inner thread of the housing opening. Advantageously, by this arrangement it can additionally be ensured that the adapter opening is arranged in a region of the housing of the power capacitor which is free of filling material or casting compound. Preferably, the common length of the first and second longitudinal sections is essentially equal to the length of the inner thread of the housing opening, or this common length is not greater than the corresponding length of the closure cap which is arranged in the housing opening.

[0019] According to another design variant of the device based on one of the two design variants described above, a third longitudinal section of the adapter body, which is connected to the second longitudinal section, is intended for fixing the adapter on the housing.

[0020] Viewed in the direction of the longitudinal axis of the columnar adapter body, the third longitudinal section, which can also be referred to as the tool section, is arranged below the first longitudinal section. For example, this section has a prismatic, in particular hexagonal, cross section, on which a suitable spanner can be connected by the fitter in order to screw the adapter into the housing opening.

[0021] According to another design variant of the device based on the design variant described above, the outer diameter of the third longitudinal section is greater than the outer diameter of the second longitudinal section.

[0022] By the larger outer diameter in the region of at least the second longitudinal section, a circumferential shoulder in the radial direction is advantageously achieved, on which a sealing ring can be arranged. Such a sealing ring, which is made of an elastic material, for example plastic, is preferably used to seal the housing with respect to the adapter body and thus to ensure the gas tightness of the housing. When the adapter is installed by screwing the outer thread of the second longitudinal section onto the inner thread of the housing opening, the shoulder exerts a mechanical force on the sealing ring in the direction of the longitudinal axis, so that the sealing ring is pressed between the shoulder and the outer edge of the housing opening. A circumferential groove can additionally be provided in the shoulder, for example, in order to ensure a defined position of the sealing ring when installed.

[0023] According to a further design variant of the device, based on one of the two design variants described above, a fourth longitudinal section, which is connected to the third longitudinal section, has an interface that is compatible with the interface of the sensor device, the fourth longitudinal section being used to mechanically connect the sensor device to the adapter body.

[0024] The interface of the sensor device and the interface of the fourth longitudinal section are designed as outer threads or inner threads, for example. The inner thread of the fourth longitudinal section is preferably designed as part of or cut into the sleeve of the adapter body here, so that the sensor device or an opening thereof, which is provided with an outer thread, directly extends into the sleeve, through which opening the sensor or membrane is subjected to pressure. Correspondingly, the fourth longitudinal section of the adapter body can also be referred to as an inner thread section.

[0025] As described above, in the case of a typical 1 / 4" outer thread of the sensor device and a 1 / 2" inner thread of the housing opening of the housing of the power capacitor, the adapter according to the application can thus also fulfill the function of a size adapter.

[0026] The cross-sectional shape of the fourth longitudinal section preferably corresponds to the cross-sectional shape of the third longitudinal section, in addition to the inner thread, or the fourth longitudinal section is designed as part of the third longitudinal section. Thereby, the overall length of the adapter can advantageously be reduced, so that the installation of the device can be achieved even if the space situation is limited. This is particularly important, since there is usually no dedicated space in the converter of a present vehicle for arranging a device for monitoring the power capacitor.

[0027] According to a further design variant of the device, the sensor device comprises at least one pressure switch, which is mechanically connected to the adapter and closes or interrupts an electrical connection when the gas pressure exceeds a predetermined threshold value.

[0028] As described above, the pressure switch has a spring-loaded membrane, for example, which is made of, inter alia, precision steel. When the settable trigger pressure is reached, the pressure switch switches or closes or opens an electrical connection acting on two electrical terminals of the pressure switch.

[0029] According to a further design of the device as an alternative to the above-mentioned design, the sensor arrangement comprises at least one pressure sensor, which is mechanically connected to the adapter and generates an electrical signal when the gas pressure exceeds a predetermined threshold value.

[0030] The sensor arrangement according to the two above-mentioned designs is particularly suitable for monitoring the gas pressure inside the housing of a power capacitor. The evaluation of the signals of the sensor arrangement or the current change triggered by these signals can be detected and evaluated, for example, by a central evaluation device, which is preferably designed to monitor all power capacitors of a converter which are equipped with a device according to the application.

[0031] Adapter of a device for monitoring a power capacitor according to the application, wherein the power capacitor has a housing, the housing interior of which can be closed gas-tight at at least one housing opening, wherein the adapter is designed to mechanically connect a sensor arrangement to the housing at the housing opening and to fluidically connect to the housing interior, wherein the adapter has a columnar adapter body which is divided into functional longitudinal sections and a sleeve for the fluidic connection which extends over the longitudinal sections, and wherein a first longitudinal section of the adapter body, which is arranged after the adapter and the housing in the region of the housing opening, closes the sleeve in a plane perpendicular to the longitudinal axis of the adapter body and fluidically connects to the housing interior in at least one plane parallel to the longitudinal axis.

[0032] According to a design of the adapter, a second longitudinal section of the adapter body, which is connected to the first longitudinal section, has an outer thread which is compatible with an inner thread of the housing opening for the mechanical connection to the housing. Here, the outer diameter of the first longitudinal section is preferably smaller than the outer diameter of the second longitudinal section.

[0033] The outer thread of the second longitudinal section can here be the same or different from the inner thread of the fourth longitudinal section. Thus, the second longitudinal section and the fourth longitudinal section, for example, each have a 1 / 4" or 1 / 2" outer thread or inner thread. Alternatively, the second longitudinal section, for example, has a 1 / 2" outer thread, while the fourth longitudinal section has a 1 / 4" inner thread, as mentioned above. Advantageously, the adapter body can be adapted in a simple manner to predetermined dimensions or diameters of the housing opening and the sensor arrangement.

[0034] According to a further design of the adapter based on the above-mentioned design, a third longitudinal section of the adapter body, which is connected to the second longitudinal section, serves to fix the adapter on the housing. Here, the outer diameter of the third longitudinal section is preferably greater than the outer diameter of the second longitudinal section.

[0035] According to a further design of the adapter according to the above design, a fourth longitudinal section, which is connected to the third longitudinal section, has a mechanical interface which is compatible with the interface of the sensor device, the fourth longitudinal section being used to mechanically connect the adapter body to the sensor device.

[0036] According to a further design of the adapter, the adapter is made of metal, in particular of fine steel or brass.

[0037] Advantageously, the adapter or its special design in the respective longitudinal section can be produced by mechanical machining of a cylindrical or prismatic metal base body. Thereby, the adapter can be produced inexpensively and has a high durability and airtightness, in particular since it can be produced from a single metal body. BRIEF DESCRIPTION OF DRAWINGS

[0038] Embodiments of the monitoring device according to the application and of the adapter according to the application are explained below with reference to the drawings. In the drawings:

[0039] Figure 1 A rail vehicle is shown as an exemplary rail vehicle, namely a railcar set;

[0040] Figure 2 An adapter connected to a housing of a power capacitor and to a sensor device is shown; and

[0041] Figure 3 A specific design of the adapter according to the application is shown. DETAILED DESCRIPTION

[0042] Figure 1 A rail vehicle is shown as an exemplary rail vehicle, namely a railcar set; Figure 1 Only one of the intermediate vehicles is shown in simplified form. The vehicles are arranged one behind the other in the direction of travel FR and are mechanically connected to one another by suitable vehicle couplings. Each vehicle has a vehicle body WK, wherein preferably all vehicle bodies WK provide passenger compartments for the accommodation of passengers. Between the vehicles, vehicle transitions are provided, through which passengers can move between adjacent vehicles or over the entire length of the railcar set.

[0043] The car bodies WK are supported on the rails of the track by bogies. Two bogies are exemplarily arranged on each car body, wherein adjacent car bodies WK are exemplarily supported on so-called Jakobs bogies. These bogies are designed as either a motor bogie TDG with at least one driven wheelset or as a guide bogie LDG with only non-driven wheelsets. According to the usual designation in the art of a driven wheelset by filling the exemplarily illustrated wheel pairs, a motor bogie TDG and a corresponding guide bogie LDG are arranged on the end vehicles EW of the motor train set TZ, the motor bogie having two driven wheelsets each. Thus, one or more intermediate vehicles MW are only supported on guide bogies.

[0044] As an alternative to the illustrated motor train set TZ with a plurality of intermediate vehicles MW, the motor train set can only comprise two end vehicles EW, on which motor bogies TDG and one or two guide bogies LDG are arranged according to Figure 1 Likewise, the rail vehicle can also be designed as a locomotive, the car bodies of which are only supported on motor bogies.

[0045] Components of the electric drive system or drive train are schematically indicated in the end vehicles EW of the motor train set TZ. These components are usually arranged in a dedicated area within the car body WK, in a floor area, in a roof area or distributed over several vehicles. Other components of the drive system, such as one or more traction batteries or auxiliary equipment required for the operation of components and passenger comfort, are not shown in Figure 1 .

[0046] The exemplary drive train of the motor train set TZ can be electrically connected to the not shown overhead line of the railway power supply network by means of a current collector PAN arranged in the roof area of the first end vehicle EW1, wherein the overhead line carries a single-phase alternating current with a voltage of 15 kV at 16.7 Hz or 25 kV at 50 Hz. This alternating current is input into the primary winding of the network side of a transformer TF, which converts the voltage level of the network side to a lower voltage level. The secondary winding of the transformer TF is connected to a network-side converter, such as a rectifier GR or a four-quadrant converter, which converts the acting alternating voltage into a direct voltage and feeds it to a direct voltage intermediate circuit ZK. According to the example of Figure 1 , the direct voltage intermediate circuit ZK is used to feed two motor-side converters, such as pulse-controlled inverters WR1, WR2, which each convert the direct voltage of the direct voltage intermediate circuit ZK into a three-phase alternating voltage with variable frequency and amplitude, with which the stator winding of the corresponding drive motor in the motor bogie TDG1 or TDG2 is fed. The function of the converters GR, WR1, WR2 is controlled, inter alia, by a central control device ST of the drive system.

[0047] Alternatively or additionally, the drive system of the rail vehicle TZ can also be electrically connected via a corresponding current collector to overhead lines or busbars carrying direct current having a voltage level of, for example, 3 kV or 1.5 kV. In this case, the direct current voltage intermediate circuit ZK can be fed, for example, directly or via a direct current transformer which converts the voltage level of the railway power supply network into the desired voltage level of the direct current voltage intermediate circuit. Furthermore, alternatively or additionally, the drive system of the rail vehicle TZ can be supplied with electrical energy by means of one or more traction batteries and / or fuel cell systems, wherein the direct current voltage intermediate circuit is, for example, in turn fed via a direct current transformer.

[0048] In the direct current voltage intermediate circuit ZK, a plurality of or some parallel-connected power capacitors are used to store electrical energy which is delivered to the motor-side converter. The power capacitors can here be arranged in the housing of the network-side or motor-side converter or else in a separate housing in the form of a so-called capacitor bank.

[0049] Figure 2 A sectional view of an adapter AD according to the application is shown schematically, which is arranged on the housing opening GO of the housing of the power capacitor LK on the one hand and on which a sensor device SE in the form of a pressure switch DS is arranged on the other hand. Only one housing wall GW of the housing of the power capacitor LK is shown, in which the housing opening GO is arranged. This housing wall GW is, for example, the housing cover of the cup-shaped housing of the power capacitor LK. The housing is, for example, made of a welded, finished steel sheet or aluminum sheet.

[0050] In the housing interior GI, one or more capacitor windings are arranged which are electrically connected to the terminals on the housing, wherein the two mentioned components of the power capacitor LK are not shown in detail. In the region of the housing wall GW, a filling material FM in the form of a casting compound is arranged in the housing interior GI, as is shown, for example, by means of the coarse dashed line. During the manufacture of the power capacitor LK, the filling material FM is injected into the housing interior GI through the housing opening GO and, after its solidification, usually has a defined but not uniform or variable distance with respect to the housing wall GW. In particular in the space thus formed, as mentioned at the outset, a gas environment consisting of thermolytic gases is produced during the operating time of the power capacitor LK.

[0051] In the region of the housing opening GO or in a region around the housing opening, the material of the housing wall GW has, for example, a greater thickness. On the one hand, this facilitates greater stability of the housing wall GW in this region, on the other hand, this serves to cut out an internal thread in order to be able to seal the housing opening GO gas-tight with a sealing cap after the housing has been filled with the filling material FM. The greater thickness can be obtained, for example, by welding in a metal ring with a pre-fabricated internal thread or by deep-drawing the housing wall material at this location. In Figure 2 In the illustration, this sealing cap has been removed and replaced by an adapter AD according to the application.

[0052] The adapter AD is composed of a cylindrical adapter body AK, which is also made of, for example, precision steel. This adapter body has a plurality of longitudinal sections along a longitudinal axis AC, as is shown in more detail below in Figure 3 The first longitudinal section has a circular cross-section, on the circumference of which a plurality of adapter openings AO are distributed. These adapter openings AO connect the gaseous environment in the housing interior GI with a central sleeve DF in the adapter body AK, as is exemplarily shown by means of flow arrows. The adapter openings AO and the central sleeve DF are shown in dashed lines.

[0053] The fluid connection of the sleeve DF of the adapter AD with the gaseous environment in the housing interior GI is ensured in that, on the one hand, the adapter openings AO are arranged in the region of the internal thread of the housing opening GO, wherein a certain distance is achieved due to the smaller outer diameter of the first longitudinal section compared to the inner diameter of the housing opening GO. On the other hand, the sleeve DF of the adapter AD is closed in the region of the housing opening GO in a plane perpendicular to the longitudinal axis AC or parallel to the housing wall GW. The closure by a part of the adapter body AK ensures that, when the adapter AD is arranged on the housing opening GO, no filling material FM can pour into the sleeve DF and thus block the sleeve.

[0054] A second longitudinal section arranged below the first longitudinal section in the longitudinal direction has an outer diameter which is compatible with the housing opening GO and an outer thread which is compatible with the inner thread of the housing opening, in order to mechanically fix the adapter AD on the housing of the power capacitor LK. In order to additionally prevent a possible escape of the pyrolysis gas into the surroundings, a sealing ring DR made of a suitable material is arranged between the third longitudinal section and the housing wall GW. The third longitudinal section is arranged below the second longitudinal section and preferably has a greater outer diameter than the second longitudinal section. By means of this greater outer diameter a circumferential shoulder is formed, by means of which a force can be exerted on the sealing ring DR in the longitudinal direction when fixing the adapter AD on the housing opening GW and the sealing ring DR can be correspondingly compressed. The cross section of the third longitudinal section is preferably at least not circular like the second longitudinal section, but rather prismatic or for example hexagonal. This cross section shape enables that the adapter AD can be screwed into the housing opening GO using a suitably dimensioned spanner.

[0055] A fourth longitudinal section arranged below the third longitudinal section or designed as a part of the third longitudinal section has an inner thread which is cut into the sleeve DF. This inner thread is preferably only cut in a partial length of the sleeve DF or only in a lower part of the sleeve, wherein this partial length is sufficient to fix the sensor device SE or the pressure switch DS on the adapter AD.

[0056] The pressure switch DS has a housing in which a membrane or a pressure sensor is arranged. The membrane or the pressure sensor is in fluid connection with the sleeve DF by means of the sensor opening SO, so that the membrane or the pressure sensor is subjected to the gas pressure present in the interior GI of the housing. The housing has a shoulder which matches the adapter body AK, by means of which a force can again be exerted on the sealing ring DR in the longitudinal direction when fixing the sensor device SE on the adapter AD and the sealing ring can be correspondingly compressed in order to prevent a possible gas escape at the interface between the adapter body AK and the pressure switch DS. The pressure switch DS has two electrical terminals EA to which electrical lines of a monitoring device are connected. Preferably, a threshold value of the gas pressure is set at which the pressure switch DS switches. Depending on the design of the pressure switch DS, reaching or exceeding the set threshold value due to an increase in the gas pressure in the housing of the power capacitor LK for example leads to a circuit being closed. The closure of the circuit and the flow of current are detected in an evaluation device and on the basis of this an alarm signal is for example emitted by the evaluation device which indicates a rising gas pressure in the power capacitor LK. This evaluation device which is not specifically shown can for example be realized as part of a central control device of the rail vehicle or as a separate unit.

[0057] Figure 3Different views of an exemplary adapter AD according to the application are schematically shown. Therein, the upper left view shows a top view of the adapter AD, i.e. an outer view of the adapter body AK. From this view and the lower right view it can be seen, for example, that the third and fourth longitudinal sections LA3, LA4 of the adapter body AK have a prismatic or hexagonal cross section. Furthermore, from the upper left view and the upper right view it can be seen that the third longitudinal section LA3 forms a circumferential shoulder with respect to the second longitudinal section LA2 or below its outer thread. The lower left view shows a cross section along the sectioning line B-B of the upper left view. From this view it can be seen, inter alia, that six adapter openings AO are arranged circumferentially in the first longitudinal section LA1 of the adapter body AK, wherein these adapter openings AO each have the shape of a circular hole which can be produced, for example, by drilling in the adapter body AK. The upper right view shows a cross section along the sectioning line A-A of the lower right view. From this view it can be seen, inter alia, an inner thread in the fourth longitudinal section LA4 for a mechanical connection with a sensor device SE or a pressure switch DS and a closure of the central sleeve in the lower region of the first longitudinal section LA1. Finally, the lower right view shows a further top view from which the cross section of the fourth longitudinal section LA4 can be seen. In contrast to the illustration in Figure 2 the fourth longitudinal section LA4 has a complementary groove around the sleeve DF or around the inner thread, which groove serves for arranging a seal.

[0058] List of reference signs

[0059] A-A sectioning plane

[0060] AC longitudinal axis

[0061] AD adapter

[0062] AK adapter body

[0063] AO adapter opening

[0064] B-B sectioning plane

[0065] EW end vehicle

[0066] DF sleeve

[0067] DR sealing ring

[0068] DS pressure switch

[0069] EA electrical connection

[0070] FM filling material

[0071] FR direction of travel

[0072] GI interior of the housing

[0073] GO housing opening

[0074] gr rectifier

[0075] gw housing wall

[0076] la1-la4 longitudinal section

[0077] lk power capacitor

[0078] mw intermediate vehicle

[0079] so sensor opening

[0080] pan current collector

[0081] se sensor device

[0082] st control device

[0083] tdg bogie

[0084] tf transformer

[0085] tz train set

[0086] wk car body

[0087] wr inverter

[0088] zk dc voltage intermediate circuit

Claims

1. An apparatus for monitoring a power capacitor (LK), wherein The power capacitor (LK) has a housing, a housing interior (GI) of which can be closed gastight at at least one housing opening (GO), and wherein the device comprises at least one sensor arrangement (SE) which emits a signal depending on the gas pressure in the housing and an adapter (AD) which mechanically connects the sensor arrangement (SE) with the housing at the housing opening (GO) and fluidically connects the housing interior (GI), wherein the adapter (AD) has a columnar adapter body (AK) which is divided into a plurality of longitudinal sections (LA1-LA4) which are functional and a sleeve (DF) for fluidic connection which extends over the plurality of longitudinal sections (LA1-LA4), wherein a first longitudinal section (LA1) of the adapter body (AK) closes the sleeve (DF) in a plane perpendicular to a longitudinal axis (AC) of the adapter body (AK) and fluidically connects the housing interior (GI) in at least one plane parallel to the longitudinal axis (AC), the first longitudinal section being arranged in the region of the housing opening (GO) after the connection of the adapter (AD) with the housing, wherein a second longitudinal section (LA2) of the adapter body (AK) which is connected to the first longitudinal section (LA1) has an outer thread which is compatible with an inner thread of the housing opening (GO) for the mechanical connection with the housing, wherein an outer diameter of the first longitudinal section (LA1) is smaller than an outer diameter of the second longitudinal section (LA2), wherein a length of the outer thread of the second longitudinal section is smaller than a length of the inner thread of the housing opening, so that after the mounting of the adapter on the housing opening, an adapter opening of the first longitudinal section is completely arranged in the region of the inner thread of the housing opening.

2. The apparatus of claim 1, wherein, A third longitudinal section (LA3) of the adapter body (AK) which is connected to the second longitudinal section (LA2) serves for fixing the adapter (AD) on the housing.

3. The apparatus of claim 2, wherein, An outer diameter of the third longitudinal section (LA3) is greater than an outer diameter of the second longitudinal section (LA2).

4. The apparatus of claim 2 or 3, wherein, A fourth longitudinal section (LA4) which is connected to the third longitudinal section (LA3) has a mechanical interface which is compatible with an interface of the sensor arrangement (SE) for the mechanical connection of the sensor arrangement (SE) with the adapter body (AK).

5. The apparatus of claim 1, wherein, The sensor arrangement (SE) comprises at least one pressure switch (DS) which is mechanically connected with the adapter (AD) and which closes or interrupts an electrical connection when the gas pressure exceeds a predetermined threshold value.

6. The apparatus of claim 1, wherein, The sensor arrangement (SE) comprises at least one pressure sensor (DS) which is mechanically connected with the adapter (AD) and which generates an electrical signal when the gas pressure exceeds a predetermined threshold value.

7. An adapter (AD) for a device for monitoring a power capacitor (LK), wherein The power capacitor (LK) has a housing, a housing interior (GI) of which can be closed gastight at at least one housing opening (GO), wherein the adapter (AD) is designed to mechanically connect the sensor arrangement (SE) with the housing at the housing opening (GO) and fluidically connect the housing interior (GI), wherein the adapter (AD) has a cylindrical adapter body (AK) divided into a plurality of longitudinal sections (LA1-LA4) that are functional and a sleeve (DF) for fluid connection that extends over the plurality of longitudinal sections (LA1-LA4), and wherein a first longitudinal section (LA1) of the adapter body (AK) encloses the sleeve (DF) in a plane perpendicular to a longitudinal axis (AC) of the adapter body (AK) and is in fluid connection with the housing interior (GI) in at least one plane parallel to the longitudinal axis (AC), the first longitudinal section being arranged in the region of the housing opening (GO) after the connection of the adapter (AD) to the housing, wherein a second longitudinal section (LA2) of the adapter body (AK) connected to the first longitudinal section (LA1) has an outer thread that is compatible with an inner thread of the housing opening (GO) for a mechanical connection to the housing, wherein an outer diameter of the first longitudinal section (LA1) is smaller than an outer diameter of the second longitudinal section (LA2), wherein a length of the outer thread of the second longitudinal section is smaller than a length of the inner thread of the housing opening, so that after the mounting of the adapter on the housing opening, the adapter opening of the first longitudinal section is completely arranged in the region of the inner thread of the housing opening.

8. The adapter (AD) according to claim 7, wherein A third longitudinal section (LA3) of the adapter body (AK) connected to the second longitudinal section (LA2) serves to secure the adapter (AD) on the housing.

9. The adapter (AD) according to claim 8, wherein An outer diameter of the third longitudinal section (LA3) is greater than an outer diameter of the second longitudinal section (LA2).

10. The adapter (AD) according to claim 8 or 9, wherein A fourth longitudinal section (LA4) connected to the third longitudinal section (LA3) has a mechanical interface that is compatible with an interface of the sensor device (SE) for a mechanical connection of the adapter body (AK) to the sensor device (SE).

11. The adapter (AD) according to claim 7, wherein The adapter (AD) is made of metal.

12. The adapter (AD) according to claim 11, wherein The adapter (AD) is made of fine steel or brass.

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