FREQUENCY CONVERTER AND FREQUENCY CONVERTER MODULE

Description

[0001] The present invention relates to frequency converters and frequency converter modules for internal and external vibrators.

[0002] Internal vibrators are used to compact liquid concrete. For this purpose, a vibrating cylinder, which is part of the internal vibrator and houses an electric motor and an imbalance driven by it at high speed, is immersed in the concrete. To achieve the required motor speed and thus the desired compaction frequency, the motor must be operated at a special voltage. The frequency of this special voltage is typically 200 Hz, which is higher than the usual mains frequency of 50 Hz or 60 Hz. Furthermore, for safety reasons, internal vibrators are operated at a voltage of, for example, 42 V, which is lower than the typical mains voltages of 400 V, 230 V, or 120 V.

[0003] The same applies to external vibrators, which are attached to a formwork wall into which concrete is being poured. The external vibrator(s) cause the formwork wall to vibrate, thereby compacting the concrete within. To achieve optimal compaction results and to adapt to the formwork in use, it is advantageous if the speed of the external vibrator(s) can be adjusted.

[0004] Since construction sites are typically powered by mains power, the special voltage required to operate internal and external vibrators must be generated using frequency converters. These typically include not only the electronics for converting the mains frequency but also electronics for transforming the voltage.

[0005] Due to the fact that different end devices require different operating parameters, there are a variety of frequency converters of different sizes. In particular, the dimensions of the transformer electronics can vary considerably depending on the voltage to be transformed and the incoming or output current.

[0006] As a result, it is often impossible to arrange a large number of frequency converters in a modular, space-saving manner. Furthermore, parts of different frequency converters are usually not interchangeable. This makes it necessary to purchase and maintain spare parts separately for each frequency converter type. This leads to high purchasing and warehousing costs, as a large number of components must be procured in small quantities and kept in stock.

[0007] US 2016 / 0172997 A1 discloses a modular converter platform in which several converters are provided for converting a direct current into an alternating current. The converters are mounted side by side on a common carrier and serve to provide electrical power for driving a vehicle. For this purpose, they are permanently installed in the vehicle.

[0008] US 2018 / 0166995 A1 shows a converter arrangement that is also permanently installed in a vehicle, with several converters that can be stacked with their housings.

[0009] These conventional converter arrangements are large and heavy, and are permanently installed in the vehicles they power. They are not suitable for use on construction sites.

[0010] DE 199 00 348 A1 discloses a control system for an electric motor-driven internal vibrator.

[0011] DE 10 2013 100 607 A1 shows an inverter with a two-part housing.

[0012] The object of the invention is therefore to provide frequency converters that can be combined to form a compact frequency converter module that can be used on a construction site and that consist largely of interchangeable parts.

[0013] This problem is solved by the subject matter of independent claim 1.

[0014] In particular, a frequency converter for converting a mains frequency into a higher frequency comprises a converter receptacle in which a circuit board is hermetically encapsulated, which circuit board is suitable for transforming an electrical current applied to the circuit board with regard to its frequency, voltage, and / or number of phases, and for outputting the transformed electrical current. The frequency converter further comprises a housing for accommodating the converter receptacle, wherein the housing is designed such that it can be positively connected to a housing of another frequency converter of similar construction.

[0015] This class of frequency converters is characterized by the fact that all frequency converters have a similarly constructed housing that can be connected to the housings of the other frequency converters in a modular manner, almost like the "Lego principle." This enables a compact combination of the frequency converters.

[0016] On the other hand, each frequency converter housing contains a converter mount, in which a circuit board containing the converter or transformation electronics is enclosed in a weatherproof and waterproof manner. Different frequency converters can therefore generate different output currents despite having the same external shape. However, since only the circuit board electronics are designed differently, while all other parts, such as electrical cables, sockets, displays, cooling systems, and the like, are identical, it is possible to maintain a set of spare parts for all frequency converters with the same housing shape. This reduces the cost of purchasing these parts, as fewer parts can be purchased in larger quantities.

[0017] The circuit board can have a transformer circuit for transforming the voltage of the applied current, preferably from a mains voltage of, in particular, 400V, 230V, or 120V to a lower voltage. Furthermore, the circuit board can have a frequency conversion circuit for transforming the frequency of the applied current, preferably from a mains frequency of, in particular, 50Hz or 60Hz to a higher frequency. Frequency converters with different output characteristics thus have the same external dimensions. In particular, transformers intended for voltage conversion are integrated on the circuit board and do not change the overall dimensions of the frequency converter, even for different current intensities and output voltages. This improves the modular combinability of frequency converters.

[0018] The frequency of the transformed electrical current can be adjusted. This allows internal and / or external vibrators to be operated at different vibration frequencies.

[0019] The housing has a cooling device for cooling the circuit board, with at least one fan capable of directing air from an air inlet of the housing via an air duct running along the converter mount to an air outlet of the housing. This allows for effective cooling of the converter electronics, as a cooling air flow is directed along the converter mount without mixing different air flows. In particular, it is possible to cool the converter mount using two non-intersecting air ducts supplied with air by fans.

[0020] The air duct is sloped at two angles, allowing any liquid that enters the air duct to drain toward the air inlet and outlet when the frequency converter is in the operating position. This allows water splashed into the frequency converter housing, for example, by rain or during cleaning, to be quickly drained away. The frequency converter thus complies with protection class IP44.

[0021] The air duct can also run through cooling fins of the converter mount.

[0022] This ensures effective heat dissipation from the circuit board via the cooling fins of the converter holder into the cooling air flow.

[0023] The housing can be equipped with indicators for various operating states, preferably for one of the following: frequency converter operation, maintenance required, overcurrent, overvoltage, or overtemperature. This makes it possible to read relevant operating parameters when working with the frequency converter and take appropriate countermeasures in the event of malfunctions. For example, in the event of (expected) overheating, a connected device can be disconnected from the overheated (or overheating) frequency converter and connected to another frequency converter, for example, located in the same module.

[0024] A frequency converter module has at least one frequency converter as described above. In addition, the frequency converter module has a base and a cover, between which the at least one frequency converter is arranged. The housing of the at least one frequency converter is designed such that a further frequency converter of the same design can be positively connected to the top or bottom of the at least one frequency converter, such that the base on the bottom of the at least one frequency converter can be positively connected to the latter, and such that the cover on the top of the at least one frequency converter can be positively connected to the latter.

[0025] Due to their similar design, multiple frequency converters can be stacked on top of each other. Furthermore, the provision of a base and a cover ensures a weatherproof enclosure for the module. The cover can also be equipped with a handle for carrying the module. Power is preferably supplied to the individual frequency converters via the cover or the base; the incoming power can then be distributed among the individual frequency converters according to the load of the connected devices. This enables compact, safe, and portable use of both a single frequency converter and multiple frequency converters.

[0026] At least two frequency converters can be arranged between the floor and the ceiling, outputting different currents, preferably from the group of 20A, 35A, and 54A. As already explained above, frequency converters with different output parameters can be connected to each other in a modular and compact manner.

[0027] An outer wall of the housing of the at least one frequency converter can have sockets for outputting the transformed electrical current. The base, the cover, and parts of the housing adjoining the outer wall can protrude from the outer wall in such a way that they extend farther from the outer wall than the sockets. This creates impact protection for the sockets of the frequency converter through laterally projecting cheeks of the housing of the frequency converter, together with the base and ceiling.

[0028] The cover can have a potentiometer that can be connected to frequency converters arranged between the base and the cover in such a way that the frequencies output by one, some, or all of the frequency converters can be adjusted via the potentiometer. This makes it possible to vary the frequencies provided to different internal vibrators connected to the frequency converter module in the same or different ways during ongoing construction site operations.

[0029] The frequency converters can be nested and secured to each other and to the floor and ceiling using fasteners such as connecting bolts or threaded rods. The frequency converter module can therefore be easily assembled and disassembled. In particular, additional frequency converters can also be retrofitted into the frequency converter module. The fasteners used for fastening can be identical for all mountings; for example, one type of bolt can be used for all connections. This further reduces the number of spare parts required.

[0030] The frequency converter module can comprise a module with a housing that is identical to the housing of the at least one frequency converter. This module can be suitable for transmitting incoming mains power via sockets. In addition to frequency converters, the frequency converter module can also contain a module that functions as a socket carrier and serves to output the mains power. Furthermore, modules with any other function can also be provided, as long as they can be implemented with an identically designed housing.

[0031] The base can be designed as a slide. This allows the frequency converter module to be easily pulled across a construction site, especially over existing reinforcements. This simplifies the use of the frequency converter module.

[0032] The invention is described below by way of example with reference to the figures. However, the invention is not defined by the described examples, but solely by the subject matter of the claims. They show: Fig. 1A und 1B schematic exploded views of frequency converters installed in frequency converter modules; Fig. 2A und 2B schematic views of the frequency converter modules; Fig. 3A und 3B schematic side views of the frequency converter modules; Fig. 4A und 4B schematic views of the frequency converters installed in the frequency converter modules; Fig. 5A und 5B schematic cross-sectional views of the frequency converter modules; and Fig. 6 a schematic view of a converter holder.

[0033] In the following, frequency converter modules 200 composed of several frequency converters 100 with the same external design are described. Fig. 1A bis 5B show different views of a frequency converter module 200 with one frequency converter 100 and of a frequency converter module 200 with two frequency converters 100. However, frequency converter modules 200 can also have more than two frequency converters 100, which are stacked one above the other according to the example with two frequency converters 100.

[0034] The core of the frequency converter modules 200 is at least one frequency converter 100, which is suitable for converting mains frequencies into higher frequencies, such as those required for the operation of internal vibrators.

[0035] The frequency converter 100 has a circuit board 120 that contains all the components necessary for transforming an incoming mains current. In particular, the circuit board has a transformer circuit for transforming a mains voltage and a frequency conversion circuit for converting a mains frequency to a higher frequency. Optionally, the circuit board can also contain electronics for converting a single-phase current into a three-phase current. The mains current can have a voltage of 400V, 230V, or 120V and a frequency of 50Hz or 60Hz. At a voltage of 400V, the mains current is three-phase. The frequency converter is preferably operated with single-phase current. This simplifies operation, as it eliminates the need for an AC / DC-sensitive residual current device.

[0036] The board is capable of boosting the frequency of the mains current to more than 200 Hz while transforming the voltage to 42 V or less. The electronics required to perform these transformations are well known and need not be explained further.

[0037] For example, in the Fig. 1B , 4A und 4B As shown, the circuit boards 120 of different frequency converters 100 can be identically dimensioned. Thus, circuit boards 120 with the same dimensions are used for different current conversions or frequency conversions. The electronic components required for the respective current conversion are therefore selected in such a way that a (substantially) uniform circuit board size is ensured. In particular, transformers present on the circuit board for voltage conversion do not change the dimensions of the circuit board, even if they are designed for converting input currents with different current intensities or for outputting different current intensities, e.g., for output currents of 20A, 35A, or 54A.

[0038] The circuit board 120 is housed in a converter mount 110, which is typically made of aluminum or another material with high thermal conductivity and sufficient stability. The circuit board 120 is encapsulated in the converter mount in a weatherproof, e.g., airtight and / or waterproof, manner. The input current is supplied to the circuit board 120 via terminals. The transformed electrical current is also discharged via terminals. The converter mount 110 can also have the same design for different frequency converters 100. The electrical properties of a frequency converter 100 can therefore be easily changed by replacing the converter mount 110 or the circuit board 120 located therein.

[0039] The converter mount 110 is arranged in a housing 130 of the frequency converter 100, which defines the external shape of the frequency converter 100. The housing 130 is constructed identically for all frequency converters 100 and allows the frequency converters 100 to be connected to one another in a modular and form-fitting manner. The dimensions of the circuit board 120 and the converter mount 110 must be at least similar enough to fit into the identically constructed housings of the various frequency converters 100. "Identically constructed" here also includes housings 130 whose outer contours allow the housings 130 to be stacked on top of one another in a form-fitting manner. Thus, housings 130 that differ only in their height or the arrangement of internal or external components, as described below, are also considered identically constructed.

[0040] For example, in the Fig. 1B As shown, the housings 130 of different frequency converters 100 can be stacked on top of one another and connected to one another by fastening bolts 240 or equivalent fastening means such as threaded rods or the like. The bottom region of the housing 130 can be designed such that it engages, for example by means of a tongue and groove, in an underlying housing 130 and stabilizes this against lateral displacement. In this way, it is possible to stack several frequency converters on top of one another in a modular manner, much like Lego bricks, in order to create a frequency converter module. As an alternative to the upward layering shown, any other modular connection is also possible that is based on the same external shape of the housings 130, e.g. placing them side by side or a ring-shaped arrangement with wedge-shaped frequency converters.

[0041] In addition to the converter receptacle 110, the housing 130 contains all other electrical components that allow the circuit board to be supplied with mains power and the transformed electrical power to be extracted. In particular, the housing 130 has supply lines to the circuit board 120, via which the mains power is fed in. The supply lines can be supplied with mains power directly via a housing wall. Alternatively, as shown in the figures, mains power can be distributed centrally to the individual frequency converters 100 via the frequency converter module 200.

[0042] From the circuit board 120, lines for the transformed current lead to sockets 160, which are arranged on an outer wall 135 of the housing. Any number of sockets is conceivable, not just the two shown. Furthermore, it is possible to apply different output currents to different sockets 160 using a single circuit board 120.

[0043] The electrical components used in the individual frequency converters 100, such as cables, sockets 160, and the like, can be identical in each frequency converter 100. This allows the electrical components of all frequency converters 100 to be serviced using a single set of spare parts.

[0044] In addition to the components required for conducting current, the housing 130 can contain additional components. For example, the frequency converter 100 can have a signaling device 150 for operating states and a cooling device for cooling the circuit board 120.

[0045] The signaling 150 can consist of various light displays, e.g., LED lights, incandescent lamps, or an LCD panel. The signaling 150 can indicate various operating states, such as the operation of the frequency converter 100, the need for maintenance, and / or the occurrence of overcurrent, overvoltage, and / or overtemperature, or the danger of such occurrence. As shown, for example, in the Fig. 3A und 3B As shown, the signaling 150 can be located in the area of ​​the connection for working equipment, such as internal vibrators, i.e. on the outer wall 135. This informs an operator of the frequency converter module 200 of the current operating state when connecting the working equipment and can react accordingly in the event of malfunctions, e.g. by switching off or not using the frequency converter 100. This increases the safety and reliability of working with the frequency converter 100.

[0046] However, the signaling 150 can also be mounted at any other externally visible location on the frequency converter 100. Furthermore, it is also possible to provide central signaling for all frequency converters 100 arranged in a frequency converter module 200.

[0047] The cooling device serves to dissipate the heat generated during the transformation of the mains voltage and thereby prevent overheating of the circuit board 120. The cooling device can have any shape that guarantees safe operation of the frequency converter 100. As shown in the figures, the cooling device of the claimed frequency converter module consists of a cooling air system that draws air into an air inlet 144 in the housing 130 by means of a fan 142, directs the air past the converter receptacle 110 in an air duct 146, and expels it through an air outlet 148 in the housing 130.

[0048] As in the Fig. 4A und 4B As shown, each frequency converter 100 may have two air ducts 146 supplied by respective fans 142, which run beneath the converter mount 110. However, any other arrangement of cooling air ducts may be used, as long as sufficient cooling of the circuit board 120 is ensured.

[0049] As in the Fig. 4A und 4B As can be seen, the air ducts 146 run along the underside of the converter holder 110. This can, as in Fig. 6 As shown, they have cooling fins 115 between which the air flows. This ensures high heat exchange and thus reliable cooling. The cooling performance is further improved by the fact that the two existing air ducts 146 do not intersect, thus preventing mixing of the air streams, which would hinder the heat dissipation.

[0050] The converter holder 110 is located, as shown in the Fig. 4A und 4B shown, on the bottom of the housing 130. To seal the air channel 146 defined by the cooling fins 115 and the bottom of the housing 130, rubber or foam mats can be attached to the housing bottom, on which the cooling fins 115 rest. Furthermore, covers 145 can be provided that cover the spaces between the cooling fins 115 and the air inlets 144 and the air outlets 148. This prevents air from leaving the predefined path desired for the cooling process, making the cooling process more efficient and reliable.

[0051] As in the Fig. 5A und 5B As shown, the housing base is inclined or bent in the area of ​​the air ducts 146 in such a way that liquids such as water flow out of the air duct 146 towards the air inlet 144 and the air outlet 148. As shown by the dashed lines in the Fig. 5A und 5B As shown, this can be achieved in that, during operation of the frequency converter 100, the area of ​​the housing base pointing towards the air inlet 144 encloses an angle α with the base of the frequency converter module 200 and the area pointing towards the air outlet 148 encloses an angle β, which may, but does not have to, differ from the angle α.

[0052] Water that enters the air ducts 146 during cleaning or due to rainfall drains out of the housing 130 automatically. Sealing the air ducts 146 from the rest of the housing 130, as achieved, for example, by providing foam mats on the housing floor, ensures that each frequency converter 100 individually complies with protection class IP44. Each frequency converter 100 individually therefore meets high safety standards.

[0053] Like the electrical components of the frequency converter 100, all other components of the frequency converter 100, as described above, can also be designed identically for each frequency converter 100. This means, in particular, that fans 142 and signaling 150 can be designed identically in each frequency converter 100. These parts are therefore interchangeable between the individual frequency converters 100, thereby reducing the number of components or spare parts required for the various frequency converters 100.

[0054] The individual frequency converters 100 are arranged in the frequency converter module 200 between a base 210 and a cover 220 of the frequency converter module 200. The contact area of ​​the base 210 has the same shape as the top of the frequency converter housing 130, while the underside of the cover 220 corresponds to the underside of the housing 130. The base 210 and the cover 220 can thus be positively connected to each other with the outermost frequency converters 100 in the same way as the frequency converters 100.

[0055] In order to connect nested frequency converters 100 to each other and to the floor 210 and the ceiling 220, similar fastening means, such as those shown in the Fig. 1A and 1BThe connecting bolts 240 shown can be used. This has the advantage that all components of the frequency converter module 200 can be connected to one another using a single type of fastening means. This also reduces the number of components required for assembly and maintenance of the frequency converter module 200.

[0056] Nested frequency converters 100, floor 210 and ceiling 220 are connected by means of the Fig. 1A and 1BThe connecting bolts 240 are screwed together using the connecting bolts 240 shown. For disassembly, the connecting bolts 240 are secured with anti-twist locks to allow the upper portion of the screw and connecting bolt to be loosened. This allows for easy assembly and disassembly of the frequency converter module. However, it goes without saying that any other type of fastening means is also possible, such as connecting bolts of different lengths, threaded rods, or offset screw points in duplicate, if these are considered advantageous.

[0057] This modular design allows frequency converters 100 to be easily inserted into or removed from the frequency converter module 200 as needed. In particular, if a frequency converter 100 fails, it can be removed separately and sent for repair without having to remove the entire frequency converter module 200 from the construction site. This prevents interruptions to work on the construction site.

[0058] The cover 220 can have a handle, as shown in the figures, which allows the frequency converter module 200 to be carried. In addition, the cover 220 can have a power plug, via which the frequency converters 100 arranged in the frequency converter module 200 can be supplied with mains power. However, the power plug can also be arranged in the base 210. Alternatively, the individual frequency converters 100 can also be provided with their own power plugs. The power fed in via the power plug can be distributed to the frequency converters 100 according to the loads applied to the frequency converters 100. This can be done directly, e.g., by a direct connection to the circuit boards 120 of the frequency converters 100. If this is advantageous, the current from the power plug can also pass through further electrical components, for example to carry out a transformation upstream of the transformation in the circuit boards 120.

[0059] As shown in the figures, a potentiometer 230 can be arranged in the cover 220. The potentiometer 230 can be used to adjust the frequency output by the frequency converters 100 of the frequency converter module 200. Frequency adjustment by means of a potentiometer is known in this case and therefore needs not be explained here. The potentiometer 230 can be connected to the circuit boards 120 of the frequency converters 100, which are to be accessible to a controller. In this way, some of the frequency converters 100 can be provided with a frequency-tunable current output, which can be used, for example, to adjust the vibration frequency of an internal vibrator or the output current to the conditions required for an external vibrator. The potentiometer 230 can also be arranged at any other location on the frequency converter module 200.In addition, the individual frequency converters can also have 100 potentiometers for frequency adjustment.

[0060] As can be seen from the figures, the outer walls of the housing 130 of the frequency converter 100, the base 210 and the cover 220 form the outer contour of the frequency converter module 200. As can be seen in particular from the Fig. 2A und 2B As can be seen, this outer contour can be used to protect the components arranged on the outside of the frequency converters 100 against external influences such as blows or impacts.

[0061] For this purpose, an outer wall 135 on which components requiring protection are arranged, here the sockets 160 and the signaling 150, is offset rearward relative to parts of the housing 130 adjacent to the outer wall. At the same time, the base 210 and the cover 220 protrude far enough in the area of ​​the outer wall 135 that they form a positive fit with the most protruding areas of the housing 130. The housing 130 thus forms protruding cheeks around the outer wall, which, together with the base 210 and the cover 220, provide impact protection for the components arranged on the outer wall 135. In other words, the outer wall 135 is set back sufficiently far relative to the surrounding parts of the housing 130, base 210, and cover 220 that the components arranged on it do not protrude.

[0062] As in the Fig. 2A und 2BAs shown, this principle can also be extended to parts of the base 210 and the cover 220, so that the housings 130 of the various frequency converters 100, the base 210, and the cover 220 form a frame, relative to which the inner parts of the housings 130, the base 210, and the cover 220 are recessed. Potentiometer 230, for example, can then be arranged in such a recess in the cover 220. This allows an area to be created on the frequency converter module 200 that is protected from knocks and impacts, in which relatively sensitive components can be mounted. This increases the service life of these components.

[0063] The frequency converter module 200 can essentially be operated in a stationary manner. However, it may also be possible to configure the base 210 of the frequency converter module 200 such that the frequency converter module 200 is movable. For example, wheels or rollers can be arranged on the base 210. Preferably, the base 210 is designed as a carriage, which allows the frequency converter module 200 to be easily pulled over a construction site surface, e.g., even over reinforcements. This simplifies the use of the frequency converter module 200.

[0064] As described above, it is therefore possible to easily combine several frequency converters into a single module, with the frequency converters being identical in terms of their dimensions and components not related to frequency conversion. It goes without saying that in such a module, it is also possible to arrange other electrical components within a housing that corresponds to that of the frequency converter. This allows the functionality of the frequency converter module to be expanded, for example, by providing a component that provides mains power via a plurality of sockets without converting it.

Claims

1. Frequency converter module (200), comprising at least one frequency converter (100) for converting a mains frequency into a higher frequency; and comprising a base (210) and a cover (220), between which the at least one frequency converter (100) is arranged; wherein the frequency converter (100) comprises a converter receptacle (110), in which a circuit board (120) is encapsulated in an air-tight manner, for transforming an electrical current applied to the circuit board (120) with regard to its frequency, its voltage and / or its number of phases and for outputting the transformed electrical current; the frequency converter has a housing (130) for accommodating the converter receptacle (110); the housing (130) is configured such that it can be connected in a form-fitting manner to a housing (130) of a similarly constructed further frequency converter (100); the housing (130) of the at least one frequency converter (100) is configured such that a further similarly constructed frequency converter (100) can be connected in a form-fitting manner to the at least one frequency converter (100) on the upper side or the lower side thereof, that the base (210) can be connected in a form-fitting manner to the at least one frequency converter (100) at the lower side thereof and that the cover (220) can be connected in a form-fitting manner to the at least one frequency converter (100) at the upper side thereof; the frequency converter module (200) is portable; the housing (130) has a cooling apparatus for cooling the circuit board (120), wherein the cooling apparatus has at least one fan (142) which is suitable for guiding air from an air inlet (144) of the housing (130) via an air duct (146), which leads along the converter receptacle, to an air outlet (148) of the housing (130); and wherein the air duct (146) is inclined in two ways such that liquid which has passed into the air duct (146) runs off to the air inlet (144) and to the air outlet (148) in an operating position of the frequency converter (100).

2. Frequency converter module (200) as claimed in claim 1, wherein the circuit board (120) has a transformer circuit for transforming the voltage of the applied current, preferably from a mains voltage of in particular 400 V, 230 V or 120 V to a lower voltage; and the circuit board (120) has a frequency converter circuit for transforming the frequency of the applied current, preferably from a mains frequency of in particular 50 Hz or 60 Hz to a higher frequency.

3. Frequency converter module (200) as claimed in any one of the preceding claims, wherein the frequency of the transformed electrical current can be set.

4. Frequency converter module (200) as claimed in any one of the preceding claims, wherein the air duct (146) runs through cooling ribs (112) of the transformer receptacle (110).

5. Frequency converter module (200) as claimed in any one of the preceding claims, wherein the housing (130) has signalisation (150) for different operating states, preferably for one of the following operating states: operation of the frequency converter (100), maintenance required, overcurrent, overvoltage, excess temperature.

6. Frequency converter module (200) as claimed in any one of the preceding claims, wherein at least two frequency converters (100) are arranged between the base (210) and the cover (220); and the two frequency converters (100) output different strengths of current, preferably from the group of 20 A, 35 A and 54 A.

7. Frequency converter module (200) as claimed in any one of the preceding claims, wherein an outer wall (135) of the housing (130) of the at least one frequency converter (100) has power points (160) for outputting the transformed electrical current; and the base (210), the cover (220) and parts of the housing (130) adjoining the outer wall (135) protrude with respect to the outer wall (135) such that they extend further away from the outer wall (135) than the power points (160).

8. Frequency converter module (200) as claimed in any one of the preceding claims, wherein the cover (220) has a potentiometer (230) which can be interconnected to frequency converters (100), which are arranged between the base (210) and the cover (220), such that frequencies of one, some or all of the frequency converters (100) which are output via the potentiometer (230) can be set.

9. Frequency converter module (200) as claimed in any one of the preceding claims, wherein the frequency converters (100) can be inserted one inside the other and can be fastened to one another and to the base (210) and the cover (220) by means of fastening means, preferably connection bolts (240) or threaded rods.

10. Frequency converter module (200) as claimed in any one of the preceding claims, wherein the frequency converter module (200) has a module with a housing which is identical to the housing (130) of the at least one frequency converter (100); and the module is suitable for relaying an incoming mains current via power points.

11. Frequency converter module (200) as claimed in any one of the preceding claims, wherein the base (210) is designed as a carriage such that the frequency converter module can be pulled across a construction site.