EP4310867A1 - Load bank - Google Patents

Abstract

The present invention relates to a load bank (1) comprising a support frame (12) and a plurality of load bank resistance modules (9) attached to the support frame (12). Each load bank resistance module (9) comprises an electrically non-conductive support plate (10) and several heating resistors designed as tubular heating elements (11), each with a heat dissipation tube (20), each of which has straight tube sections (20a) and at least one curved tube section (20b). The tubular heating elements (11) are each attached to one of the electrically non-conductive support plates (10). The support frame (12) has a corresponding module opening (23) for each load bank resistance module (9), which is each dimensioned such that the heat dissipation tubes (20) of a load bank resistance module (9) can be passed through the module opening (23) and the support plate (10 ) of a load bank resistance module (9) overlaps the corresponding module opening (23). The load bank resistance modules (9) are each fastened to the support frame (12) in that the electrically non-conductive support plates (10) of the load bank resistance modules (9) are each fastened to the support frame (12), so that the support frame (12) together with the support plates (10 ) separates a waste heat area (13) from a contacting area (14). The contact points (19) are arranged in the contact area (14). The straight pipe sections (20a) of the heat dissipation pipes (20) are arranged lying in the waste heat area (13) in relation to their longitudinal extent.

Description

The present invention relates to a load bank comprising a support frame and a plurality of load bank resistance modules attached to the support frame.

Such load banks are also referred to as high-performance resistors and typically have heating resistors in which electrical energy is converted into heat, which is then dissipated by natural or forced convection (through a fan) to prevent overheating. Load banks have been known for many years and are used for a wide variety of applications, for example as grounding resistors, track resistors, braking resistors or load banks for generator testing.

The document is an example of the large pool of revelations DE 10 2018 105 558 A1 selected, which describes a load bank of the type described at the beginning, in which tubular heating elements are combined into modules, mounted upright on strips and contacted from below, in particular in order to minimize the heat load on the contact points.

Against this background, the present invention is based on the object of providing a load bank with improved practical suitability, particularly in terms of efficiency, compactness, safety, longevity, reliability and ease of maintenance.

This task is solved by the load bank according to claim 1. The load bank comprises a support frame and a plurality of load bank resistance modules attached to the support frame, each load bank resistance module having an electrically non-conductive support plate and several designed as tubular heating elements Includes heating resistors. The tubular heating elements each have two contact points, a heat dissipation pipe and a heating wire arranged in the heat dissipation pipe, which is electrically insulated from the heat dissipation pipe by an insulation material surrounding the heating wire and is electrically connected to the contact points. The heat dissipation pipes each have straight pipe sections and at least one curved pipe section. The tubular heating elements are each attached to one of the electrically non-conductive support plates. The support frame has a corresponding module opening for each load bank resistance module, which is dimensioned such that the heat dissipation tubes of a load bank resistance module can be passed through the module opening and the carrier plate of a load bank resistance module overlaps the corresponding module opening. The load bank resistance modules are each attached to the support frame in that the electrically non-conductive support plates of the load bank resistance modules are each attached to the support frame, so that the support frame, together with the support plates, separates a waste heat area from a contacting area. The contact points are arranged in the contact area. The straight pipe sections of the heat dissipation pipes are arranged lying in the waste heat area relative to their longitudinal extent.

Through the synergistic interaction of the features according to the invention, a load bank can be provided which has improved practical suitability in several respects.

Because each carrier plate overlaps the associated (corresponding) module opening in the carrier frame in the longitudinal and/or transverse extent (so that the carrier plates cannot be guided through the module openings), the carrier plates form together with the carrier frame a (continuous) wall-like barrier that separates the waste heat area from the contacting area. In this way, the heat load emitted by the heat dissipation pipes can be focused in the waste heat area and, to a certain extent, shielded and kept away from the contacting area. The temperature load in the contact area is therefore relatively low, which benefits the service life and reliability of the load bank.

By grouping several tubular heating elements in modules to form a load bank resistance module (having a common support plate), faulty tubular heating elements can be removed and replaced easily and quickly (module-specifically), which improves ease of maintenance. The fact that the straight pipe sections of the heat dissipation tubes are arranged horizontally in relation to their longitudinal extent not only makes it easier to "thread in and out" the heat dissipation pipes through the associated module opening when installing and removing the modules, but also ensures efficient heat dissipation beneficial. The horizontal arrangement of the straight pipe sections of the heat dissipation pipes transversely to the air flow direction promotes the formation of turbulent flows, which can improve heat dissipation.

The statement that the straight pipe sections of the heat dissipation pipes are arranged horizontally relative to their longitudinal extent is to be understood in the present case in the sense that the straight pipe sections are arranged transversely to the vertical air flow that forms in the waste heat area. If the longitudinal extension of the straight tube sections of the heat dissipation tubes forms an angle of less than 25° (in particular less than 20°) with the horizontal, this is to be understood as lying in the present sense.

The heat dissipation pipes each have straight pipe sections (running parallel to each other) and at least one curved (deflection) pipe section. In this way, a space-saving meandering course of the heat dissipation pipes can be achieved. Each meandering heat dissipation tube advantageously extends in a plane that is preferably oriented horizontally. Alternatively, the heat dissipation pipe can also extend in a vertical plane.

According to the invention, the heat dissipation pipes are not electrically connected to the (electrically grounded) support frame. This means that even if the insulating material loses its insulating effect and electrical contact is established between a heating wire and a heat dissipation tube, a ground fault (short circuit) between the heating wire and the support frame can be prevented. This is beneficial for operational safety. The support frame can form part of the housing body.

The load bank preferably comprises a fan which is suitable for causing a vertical draft in the waste heat area of the load bank. In this way, an air flow (preferably directed vertically upwards) with such a high flow velocity can be provided in the waste heat area, so that forced convection occurs with the formation of turbulent flow conditions on the surface of the heat dissipation pipe, which benefits the heat dissipation and thus the efficiency of the load bank.

Furthermore, the load bank can include a heat protection plate, which is arranged parallel to the support plates in the waste heat area and has pipe openings through which the Heat dissipation pipes can be passed through. In this way, the contact area can be shielded even more effectively from thermal stress.

According to a preferred embodiment of the load bench according to the invention, the support plates are made of mica, in particular of micanite. Mica or, in particular, micanite is an electrical insulator, mechanically and thermally relatively stable, easy to process and relatively inexpensive - and therefore particularly suitable as a carrier plate material.

Magnesium oxide can be used as an insulation material.

According to a further preferred embodiment, the tubular heating elements each have a flange and (the tubular heating elements) can be releasably attached to one of the support plates by inserting the respective tubular heating element into at least one pipe opening in the support plate up to the stop on the flange and releasably attaching it in this position. In this way, the tubular heating element can be easily attached to the support plate and at the same time it can be achieved that - when the flange lies fully against the support plate - the straight pipe sections of the heat dissipation pipe of the associated tubular heating element have the desired lying orientation.

Very particularly preferably, the tubular heating elements can each be releasably fastened by means of at least one screwed nut. This type of fastening enables, on the one hand, the re-tightening of the connection (to compensate for settlement phenomena that occur over time) and, on the other hand, the simple replacement of individual faulty pipe heating elements. Both contribute to the ease of maintenance of the load bank.

A seal, in particular a silicone seal, is particularly preferably provided between the flanges and the carrier plates. This means that the entry of ambient air humidity into the volume filled with insulation material between the heating wire and the heat dissipation piping can be largely prevented. The insulation material is typically highly hygroscopic and loses its electrical insulating properties as the moisture load increases. Against this background, the reliability and longevity of the load bank can be increased by effectively sealing the insulation material from the ambient humidity.

Furthermore, the load bank can comprise electrically non-conductive guide plates, in particular made of micanite, with recesses through which the tubular heating elements can be passed. With the help of these guide plates, it is possible to prevent long tubular heating elements from bending or sagging due to their own weight and, as a result, touching the housing of the load bench. This would disadvantageously lead, on the one hand, to an undesirable introduction of heat into the housing and, on the other hand (in the event of a short circuit between the heating wire and the heat dissipation tube), lead to a short to ground between the heating wire and the housing. The guide plates therefore have a beneficial effect on the operational safety and longevity of the load bank. Furthermore, the guide plates enable the use of tubular heating elements with longer heat dissipation tubes.

In addition, the guide plates, which divide the waste heat area into several sub-chambers, support the formation of a homogeneous flow pattern in the waste heat area. In this way, an air flow with even higher flow velocities is formed in the vertical direction, which is what the Heat transfer and thus the efficiency of the load bank benefits.

Fig. 1A - 1B

eine Lastbank in einer Schnittansicht (Fig. 1A) und einer Vorderansicht (Fig. 1B),

Fig. 2

die Lastbank gemäß den Figuren 1A und 1B mit nach vorne geklappter Montageplatte und einem teilweise herausgezogenen Lastwiderstandsmodul in Schnittansicht,

Fig. 3A - 3C

drei Lastbankwiderstandsmodule samt einer Trägerplatte in einer Draufsicht (Fig. 3A), einer Seitenansicht (Fig. 3B) und einer Vorderansicht (Fig. 3C), und

Fig. 4A - 4B

drei Lastbankwiderstandsmodule samt einer Trägerplatte in einer perspektivischen Hinteransicht (Fig. 4A) und einer perspektivischen Vorderansicht (Fig. 4B).

An exemplary embodiment of the invention is explained in more detail below with reference to the drawing. This shows

Figs. 1A - 1B

a load bank in a sectional view ( Fig. 1A ) and a front view ( Fig. 1B ),

Fig. 2

the load bank according to the Figures 1A and 1B with the mounting plate folded forward and a partially pulled-out load resistance module in a sectional view,

Figs. 3A - 3C

three load bank resistance modules including a carrier plate in a top view ( Fig. 3A ), a side view ( Fig. 3B ) and a front view ( Fig. 3C ), and

Figs. 4A - 4B

three load bank resistance modules including a support plate in a perspective rear view ( Fig. 4A ) and a perspective front view ( Fig. 4B ).

First of all, reference should be made to the Figures 1A to 2 The general structure of the load bank will be explained before specific details with reference to the Figures 3A to 4B be executed.

The Figures 1A and 1B show a load bank 1 in a sectional view or a front view. The load bank 1 has a housing body 3 resting on four feet 2, on the front of which a control cabinet 4 is attached, which can be opened by means of two doors 5. Through an opening 6 on the underside of the housing body 3 can be used A fan 7 mounted there creates a vertically upward air flow (draft) within the housing body 3. The housing body 3 has a further opening 8 in the upper area through which the air flow can leave the housing body 3.

Arranged in the housing body 3 are several load bank resistance modules 9, each of which has a support plate 10 and several heating resistors designed as tubular heating elements 11 attached to it. If the heating resistors of the load bank resistance modules 9 are supplied with electricity during normal operation, this is converted into heat and the heat is removed from the load bank 1 by means of the air flow. For this purpose, the housing body 3 comprises an electrically conductive and grounded support frame 12, to which the load bank resistance modules 9 are attached via the non-conductive support plates 10.

The carrier plates 10 and the carrier frame 12 together form a barrier that separates a waste heat area 13 (which extends within the housing body 3) from a contacting area 14 (which extends within the control cabinet 4).

A mounting plate 15 is arranged within the control cabinet 4, to which electrical and electronic components 16 are attached and which is rotatably mounted on the control cabinet base 18 by means of a joint 17.

As in Figure 2 illustrated, the mounting plate 15 can be folded forward by rotating around the joint 17 when the control cabinet doors 5 are open. As a result, the load resistor modules 9 are accessible through the control cabinet 4 (i.e. from the front) and can be removed from the housing body 3 (towards the front), for example for maintenance or repair purposes. be removed. An in Figure 2 The load module 9 shown is shown in a state partially pulled out of the housing body 3.

The Figures 3A to 3C as well as 4A and 4B each show a section of the load bank 1 comprising three load bank resistance modules 9 together with the adjacent support frame 12 according to the Figures 1A to 2 . Each load bank resistance module 9 has an electrically non-conductive carrier plate 10 made of micanite and ten heating resistors designed as tubular heating elements 11. Each tubular heating element 11 has two contact points 19, a heat dissipation pipe 20 and a heating wire arranged in the heat dissipation pipe 20, which is electrically insulated from the heat dissipation pipe 20 by an insulation material surrounding the heating wire and is electrically connected to the contact points 19. Each heat dissipation tube 20 has a meandering course, which is formed by four straight tube sections 20a and three curved (semicircular) (deflection) tube sections 20b. Like from the top view Figure 3A and the side view Figure 3B As can be seen, the meandering heat dissipation tubes 20 each extend in a horizontal plane.

Each tubular heating element 11 has two flanges 22 and is releasably attached to the carrier plate 10 by inserting it into pipe openings in the carrier plate 10 until it stops against the flanges 22 and in this position by means of screwed nuts 23 (on the side of the carrier plate opposite the flanges 22 10 are arranged) is screwed. A silicone seal is provided between the flanges 22 and the carrier plates 10.

The support frame 12 has a corresponding module opening 24 for each load bank resistance module 9, which is dimensioned such that the heat dissipation tubes 20 one Load bank resistance module 9 can be passed through the module opening 24 and the carrier plate 10 of a load bank resistance module 9 overlaps the corresponding module opening 24. The carrier plate 10 is designed to be larger in its longitudinal and transverse extent than the associated module opening 23. The load bank resistance modules 9 are attached to the carrier frame 12 by screwing the electrically non-conductive carrier plates 10 of the load bank resistance modules 9 to the carrier frame 12 using screws 25 and thus releasable are attached. Also visible is a heat protection plate 26 arranged parallel to the carrier plates 10 with pipe openings 26a and two electrically non-conductive guide plates 27 made of micanite with recesses 27a through which the pipe heating elements 11 can be passed. The straight tube sections 20a of the heat dissipation tubes 20 are each arranged horizontally along their longitudinal extent (and form an angle of 0° with the horizontal).

The Figures 3A and 3B , 4A and 4B each show two load resistance modules 9, which are already screwed to the support frame 12, while in a load resistance module 9 the heat dissipation tubes 20 are guided or threaded through the module opening 23, the heat shield plate 26 and the guide plates 27.

The carrier plates 10 screwed to the carrier frame 12 together form a barrier that separates a waste heat area 13 from a contacting area 14, the contact points 19 being arranged in the contacting area 14.

Claims (9)

Load bank (1) comprising a support frame (12) and a plurality of load bank resistance modules (9) attached to the support frame (12), wherein - each load bank resistance module (9) comprises an electrically non-conductive carrier plate (10) and several heating resistors designed as tubular heating elements (11), - The tubular heating elements (11) each have two contact points (19), a heat dissipation pipe (20) and a heating wire arranged in the heat dissipation pipe (20), which is electrically insulated from the heat dissipation pipe (20) by an insulation material surrounding the heating wire and with the contact points (19 ) is electrically connected, - the heat dissipation pipes (20) each have straight pipe sections (20a) and at least one curved pipe section (20b), - the tubular heating elements (11) are each attached to one of the electrically non-conductive support plates (10), - the support frame (12) has a corresponding module opening (23) for each load bank resistance module (9), which is each dimensioned such that the heat dissipation tubes (20) of a load bank resistance module (9) can be passed through the module opening (23) and the support plate (10 ) of a load bank resistance module (9) overlaps the corresponding module opening (23), and - the load bank resistance modules (9) are each attached to the support frame (12) by the electrically non-conductive support plates (10) of the load bank resistance modules (9) each being attached to the support frame (12), so that - the carrier frame (12) together with the carrier plates (10) separates a waste heat area (13) from a contacting area (14), - the contact points (19) are arranged in the contact area (14), and - The straight pipe sections (20a) of the heat dissipation pipes (20) are arranged lying in the waste heat area (13) in relation to their longitudinal extent. Load bench (1) according to claim 1, wherein
the load bank (1) comprises a fan (7) which is suitable for causing a vertical draft in the waste heat area (13) of the load bank (1). Load bench (1) according to one of the preceding claims, wherein the load bench (1) comprises a heat protection plate (26) which is arranged parallel to the support plates (10) in the waste heat area (13) and has pipe openings (26a) through which the heat dissipation pipes ( 20) can be passed through. Load bench (1) according to one of the preceding claims, wherein the support plates (10) are made of mica, in particular of micanite. Load bench (1) according to one of the preceding claims, wherein the insulation material is magnesium oxide. Load bench (1) according to one of the preceding claims, wherein the tubular heating elements (11) each have a flange (22) and can be releasably attached to one of the support plates (10) by the respective tubular heating element (11) being attached to the flange (22) as far as it will go ) can be inserted into at least one pipe opening in the support plate (10) and can be releasably fastened in this position. Load bench (1) according to claim 6, wherein the tubular heating elements (11) can each be releasably fastened by means of at least one screwed nut. Load bench (1) according to one of claims 6 or 7, wherein a seal, in particular a silicone seal, is provided between the flanges (22) and the support plates (10). Load bench (1) according to one of the preceding claims, wherein the load bench (1) comprises electrically non-conductive guide plates (27), in particular made of micanite, with recesses (27a) through which the tubular heating elements (11) can be passed.

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