AU2016245920A1

AU2016245920A1 - Power converter system and load interrupter comprising such a power converter system

Info

Publication number: AU2016245920A1
Application number: AU2016245920A
Authority: AU
Inventors: Klaus Dietmar Kahler; Martin Schröder
Original assignee: EFEN GmbH
Current assignee: EFEN GmbH
Priority date: 2015-04-09
Filing date: 2016-04-07
Publication date: 2017-11-09
Also published as: CN107636788A; EP3281215B1; BR112017021473A2; DE102015105441A1; WO2016162404A1; HK1245992A1; EP3281215A1

Abstract

The invention relates to a power converter system comprising a power converter, which detects a current flowing through the power converter and converts said current into a measurement voltage, and an electronic evaluation system which is connected to the power converter and which processes the measurement voltage, wherein the power converter and the electronic evaluation system are arranged in a system housing. The invention is to provide a power converter system or a load interrupter comprising such a power converter system which prevents the aforementioned disadvantages. According to the invention, this is achieved in that an interrupter device is provided for temporarily interrupting the connection between the power converter and the electronic evaluation system.

Description

Current transformer system as well as load break switch comprising the same

The present invention concerns a current transformer system as well as a load break switch comprising a current transformer system.

Load break switches include NH fuse switches as well as NH fuse rails, which generally comprise a housing with a base plate and at least one supply terminal and at least one output terminal.

Load break switches of this kind have been known for a long time and have the purpose of providing fused branches from busbars that can be switched off under load. To facilitate that, said devices are provided with one or more fuse bases that are disposed in the housing. The corresponding fuses are, for example, mounted on a switch cover, so that, with the switch cover closed, the fuses are inserted into the fuse bases and make a connection between the respective supply terminals, which are to be connected to the busbars, and the output terminals. When opening the switch cover, the fuses are pulled out from the fuse bases, thus breaking the connection.

The present invention may in principle also be used with open distribution rails where the fuses are pulled from the open housing using a suitable tool. The terms load break switch and NH fuse rail therefore include the open distribution rails.

In some applications it is desired to measure the current flowing through the provided output terminal. Current transformers are most commonly used for this purpose. Current transformers operate like transformers, that is, an alternating current flowing through the output terminal (primary conductor) induces a secondary current in a secondary conductor provided by the current transformer, which is galvanically separated from the primary circuit, which may be used to measure the primary current. This is therefore a non-contact measuring method.

Plug-on current transformers are known, for example, that comprise a primary conductor (for example in form of an electrically conductive cylinder part) and a secondary conductor that surrounds said primary conductor. During installation the current transformer is attached to the supply terminal so that the primary conductor iiicmco υυιιιαυι vvim me ουμμιγ lemmiai emu me μίΜΐιαίγ uumuuului ui me uuiieiii transformer takes up the current flowing through the supply terminal.

The common factor between the described current transformer systems is that the connection of the secondary conductor to a corresponding evaluation device is cumbersome since each current transformer has to be connected with two wires, and the installation thereof has to be short-circuit proof.

The document DE 10 2007 051 419 describes a NH fuse rail, which provides on the underside of the housing a current transformer module consisting of three different current transformers, each of which is connected to a supply terminal. However, even with this embodiment it is necessary to connect, if required, an electronic evaluation device to a display device and the required current transformer. Evaluation devices and in particular display devices are expensive, cannot be installed in the switchboards and are only connected to the respective current transformer if required.

It is also in this instance necessary for a technician to connect the current transformer to the evaluation and display device on site in order to ascertain the amount of current that flows through the corresponding output terminal. A current transformer system is already known from DE 10 2011 052 449 A1 that comprises an evaluation device that evaluates the measured voltage. In this instance the electronic evaluation circuit and the current transformer are disposed in the system housing of the current transformer system.

The checking of overload and overvoltage situations is often required, in particular when installing the above-described load break switches in switchboards. Amongst other things, a higher voltage than in normal operation is applied to the load break switch to observe the behaviour of the load break switch.

However, increasing the voltage in the primary circuit leads automatically to a voltage increase in the secondary circuit, which causes the destruction of the evaluation device of the current transformer system.

Although it is possible to protect the evaluation device with its own fuse to prevent its destruction through overvoltage, the consequence is that this fuse has to be replaced after every overvoltage test, which is rather costly.

Thus it is current practice to remove the entire current transformer system from the load break switch prior to an overvoltage test, and the load break switch is operated without the current transformer system during the overvoltage test. After a successful overvoltage test the current transformer system is them installed again on the load break switch. However, the load break switch often comes with three supply terminals and three output terminals, which means that the current transformer system comprises three current transformers through which the respective output must be passed. Additionally, an appropriate power conductor has to be attached to the output terminal. To facilitate the removal of the current transformer system from the load break switch, said load break switch must be isolated, the corresponding power conductors have to be disconnected, the current transformer system pulled off and the power conductors reconnected. After completion of the overvoltage test the power conductors must again be disconnected, the current transformer system attached and the power conductors reconnected. The removal and reinstallation of the current transformer system is thus very time-consuming.

Based upon the described prior art it is the object of the present invention to provide a current transformer system, or a load break switch respectively comprising such a current transformer system, that avoids the described disadvantages.

According to the invention this object is met in that a separating device is provided to provide a temporary disconnection between current transformer and electronic evaluation circuit.

Said separating device may, for example, be a switch or a plug connection through which the current transformer is separated from the electronic evaluation circuit. If an overvoltage occurs in the primary circuit during the separation of the current transformer from the electronic evaluation circuit this also causes an overvoltage in the secondary circuit. However, since the secondary circuit is not closed and, respectively, the electronic evaluation circuit is separated from the current transformer, this does not lead to an overvoltage on the electronic evaluation circuit.

As soon as the respective overvoltage test is completed, the separating device can be operated again, thus establishing again the connection between the current transformer and the electronic evaluation circuit.

In a preferred embodiment the system housing of the current transformer system comprises a current transformer compartment that houses the current transformer, as well as an evaluation electronics compartment that houses the electronic evaluation circuit.

The current transformer itself consists essentially of the secondary conductor that surrounds the primary conductor. In this instance the primary conductor may either be provided by the load break switch or it may be part of the current transformer, where in the latter instance the primary conductor is connected to the supply terminal or to the output terminal.

Since the current transformer, and thus the secondary conductor and the electronic evaluation circuit, are housed in separate compartments, it is possible that, in a preferred embodiment, the current transformer compartment and the evaluation electronics compartment can be moved in a reciprocating motion relative to each other between a separating position, in which the separating device breaks the connection between current transformer and the electronic evaluation circuit, and a contact position in which the separating device establishes the connection between the current transformer and the electronic evaluation circuit. If the separating device has, for example, a plug connection, it is disconnected in the separating position, whereas it is connected in the contact position. In essence, the evaluation electronics compartment, which houses the electronic evaluation circuit may, in the exemplary embodiment described, be moved relative to the current transformer housing, which separates the connection between the two compartments. The overvoltage test can now be carried out, and after completion of the test the evaluation electronics compartment can be moved back into the contact position. Particularly when the evaluation electronics compartment houses the electronic evaluation circuit for multiple current transformers, the displacement of the chamber makes it very simple to temporarily disconnect the contact between all current transformers and the electronic evaluation circuit.

To facilitate the guidance of the relative movement between the evaluation electronics compartment on the one hand and the current transformer compartment on the other, a guide device is provided in a further embodiment, which permits a relative movement between current transformer compartment and evaluation electronics compartment in a separation direction but prevents a relative movement at least in a perpendicular direction thereto.

It is possible, for example, that the evaluation electronics compartment is linked to the current transformer compartment via a sliding guide. The term sliding guide means a linear guide in which the guiding elements of the guide device slide on each other and are not separated from each other through roller bearings. A sliding guide of this kind may be achieved, for example, through linear friction bearings, dovetail guides or by means of guide rails.

In a further preferred embodiment either the current transformer compartment or the evaluation electronics compartment is provided with one or more protrusions, and the other housing compartment is provided with a slot-like recess with which the protrusion engages. If the recess is larger than the protrusion, the protrusion is able to move back and forth between different positions within the recess. The recess may, for example, be provided in the form of a slot, enabling the protrusion to be moved along the slot so as to move the evaluation electronics compartment into the contact position or into the disconnect position.

In a further preferred embodiment first latching means are provided through which the evaluation electronics compartment and the current transformer compartment can be retained in the disconnect position and/or the contact position. Said first latching means may be shaped such that in the disconnect position and/or in the contact position the guide device provides an increased static or sliding friction between the guide elements of the guide device.

This may be achieved, for example, in that the latching means have to be elastically deformed so as to move the evaluation electronics compartment from the disconnect position and/or the contact position. For example the slot-like recess may have a tapered section, where the width of said tapered section is somewhat smaller than the width of the protrusion so that the protrusion can only be moved past the tapered section if the width of the slot is enlarged through elastic deformation. In this instance it is also possible to provide the tapered section in form of a correspondingly positioned spring element.

This measure ensures that an unintended relative movement between evaluation electronics compartment and current transformer compartment is prevented since the relative movement is only possible by applying a corresponding force.

In a further preferred embodiment second latching means are provided through which the evaluation electronics compartment and the current transformer compartment can be retained in the contact position and/or the disconnect position, which are shaped such that the evaluation electronics compartment and the current transformer compartment can only be moved from the contact position and/or the disconnect position if the second latching means are released.

In this embodiment a bar, for example, engages with the above-described recess so as to prevent movement of the protrusion within the recess. If the evaluation electronics compartment is to be moved from the contact position in the direction of the disconnect position, the bar must first be removed from the recess.

The system housing may, for example, be provided with a connecting space that is attached to the current transformer compartment, in which connecting means are disposed for connecting a power conductor. The current transformer system may, for example, be designed such that it can be pushed over the existing output terminal so that the output terminal extends as the primary conductor through the current transformer into the connecting space, where it then is connected to the respective outgoing conductors. Said connecting space may be provided with a connecting space cover, which can be opened or closed respectively for connecting or disconnecting the power conductor to or from the primary conductor. Provision is now made in a preferred embodiment where the second latching means are disposed on the connecting space cover. The above-described bar may, for example, be disposed on the connecting space cover so that, when the connecting space cover is placed on the connecting space, the bar engages with the recess and prevents the evaluation electronics compartment from being moved from the contact position.

Moreover, the present invention concerns NH fuse rails or NH fuse switches comprising a housing with a base plate and at least one supply terminal, which preferably protrudes over the base plate, and at least one output terminal as well as at least one fuse, which when inserted connects the supply terminal with the output terminal, wherein, according to the invention, a current transformer system, as described above, is provided. A particularly preferred embodiment provides that the current transformer is arranged such that it surrounds the output terminal.

Further advantages, characteristics and application options of the present invention are made apparent by way of the following description of a preferred embodiment as well as through the corresponding Figures. Shown are in:

Figure 1 a lateral view of a current transformer system according to the invention;

Figure 2 a lateral view of a current transformer system in Figure 1 with removed cover in contact position;

Figure 3 a lateral view of a current transformer system in Figure 1 and 2 with removed cover in disconnect position;

Figure 4 a perspective view of the current transformer system in Figures 1 to 3;

Figure 5 a plan view of the current transformer system in Figures 1 to 4, and

Figure 6 a perspective view of a load break switch with a corresponding current transformer system.

The Figure 1 depicts a lateral view of a current transformer system 1 according to the invention. The current transformer system 1 comprises a system housing 2, 3, 4 that consists of the current transformer compartment 2, the evaluation electronics compartment 3 as well as a terminal block 4, which is obscured by the terminal block cover 7. Disposed inside the current transformer compartment 2 is the current transformer, which essentially consists of the secondary conductor. The Figure depicts an output terminal 5, which may either form part of the current transformer system 1 or may be part of a load break switch (not shown). In the latter instance the primary conductor 5 takes the form of the output terminal of the load break switch.

Arranged in the evaluation electronics compartment 3 are the corresponding electronic evaluation circuits, which essentially consist of a printed circuit board, fitted with electronic components. The purpose of the electronic evaluation circuit is to evaluate the measuring voltage provided by the current transformer. Said measuring voltage, which is provided by the current transformer, is made available via the plug 6 of the electronic evaluation circuit 3. The terminal block 4 is shown above the evaluation electronics compartment 3. The basic purpose of said terminal block is to create a space in which the respective output conductors are connected to the primary conductor 5 that passes through the current transformer.

The terminal block 4 is provided with a connecting space cover 7. The Figure 2 depicts a corresponding view of the current transformer system 1 with the connecting space cover 7 removed.

It is apparent that the evaluation electronics compartment 3 is provided with two protruding tabs 9, which are provided with elongated recesses 12 that pass fully through the tabs. Corresponding protrusions 10 are disposed in the current transformer compartment or, respectively, on the terminal block 4 that is connected to it, which are positioned inside the recesses 12. The recesses 12 are elongated so that the evaluation electronics compartment 3 can be moved back and forth relative to the current transformer compartment 1 in the direction of the arrow.

To prevent the inadvertent release of the tabs 9 from the terminal block 4, guides 11 are provided in which the tabs 9 are guided. Said guides extend past the protrusions 10. The connecting space cover 7 is provided with corresponding slots in which the protruding guides 11 are disposed when the evaluation electronics compartment is in contact position and the connecting space cover 7 is placed into position. As the connecting space cover 7 is placed into position, it snaps into place via the latch 18 on the terminal block 4 so that the connecting space cover 7 cannot be moved relative to the evaluation electronics compartment 3. Since the guides 11 simultaneously engage with the slots, the evaluation electronics compartment 3 cannot be moved from the contact position without first removing the connecting space cover 7. The second latching means are realised in this embodiment through the connecting space cover 7.

In the position depicted in Figure 2 the current transformer housing 2 is connected via the plug 6 to the evaluation electronics compartment so that the electronic evaluation circuit is supplied with the measuring voltage, which is provided by the secondary conductor of the current transformer.

The Figure 3 depicts a lateral view of the current transformer system according to the invention in disconnect position. The Figure 3 differs from Figure 2 in that the evaluation electronics compartment 3 has been moved into the disconnect position, that is, to the right in Figure 3. It is apparent that the protrusion 10, which is rigidly connected to the current transformer, is now located at the left end of the recess 12.

Figure 4 depicts a perspective view of the current transformer system 1. It is apparent that the system 1 is comprised of three current transformers 2. The connecting space cover 7 is provided on its side that is facing away from the current transformers 2 with three half-round recesses 13 through which the respective power conductors may be routed.

Figure 5 depicts a plan view of the current transformer system 1.

And lastly, Figure 6 shows a perspective view of a load break switch 14, attached to which is a corresponding current transformer system 1. The load break switch14 comprises a housing 15 with a supply terminal disposed on the underside, which may be connected to appropriate busbars. Corresponding fuse bases are disposed inside housing 15, wherein appropriate fuses are located on switch cover 16. The switch cover 15 can be pivoted via a hinge joint 17 relative to housing 15, wherein the fuses are pulled out from the fuse bases when cover 16 is opened, so that there is no connection between the supply terminals and the output terminals. The current transformer system 1 is pushed onto the output terminals.

List of reference numbers 1 Current transformer system 2 Current transformer 3 Evaluation electronics compartment 4 Terminal block 5 Primary conductor 6 Plug 7 Connecting space cover 8 Recess of connecting space cover 9 Tabs 10 Protrusion 11 Guide 12, 13 Recess 14 Load break switch 15 Housing 16 Cover 17 Hinge joint 18 Latch

Claims

Claims

1. A current transformer system comprising a current transformer, which measures a current that flows through the current transformer and converts it into a measuring voltage, and an electronic evaluation circuit that is connected to the current transformer and processes the measuring voltage, wherein the current transformer as well as the electronic evaluation circuit are disposed inside a system housing, characterised in that a separating device is provided for the temporary breaking of the connection between current transformer and electronic evaluation circuit.
2. The current transformer system according to claim 1, characterised in that the separating device is a switch.
3. The current transformer system according to claim 1 or 2, characterised in that the system housing comprises a current transformer compartment that houses the current transformer, as well as an evaluation electronics compartment that houses the electronic evaluation circuit.
4. The current transformer system according to claim 3, characterised in that the current transformer compartment and the evaluation electronics compartment can be moved in a reciprocating motion relative to each other between a separating position, in which the separating device breaks the connection between current transformer and the electronic evaluation circuit, and a contact position in which the separating device establishes the connection between the current transformer and the electronic evaluation circuit.
5. The current transformer system according to claim 4, characterised in that a guide device is provided, which permits a relative movement between current transformer compartment and evaluation electronics compartment in a separation direction but prevents a relative movement at least in a perpendicular direction thereto, wherein the guide device preferably prevents a relative movement in all directions perpendicular to the separation direction.
6. The current transformer system according to claim 5, characterised in that the guide device is provided with a protrusion as well as a recess that corresponds to said protrusion, wherein the protrusion is either located on the current transformer compartment or on the evaluation electronics compartment and the recess is located on the other compartment.
7. The current transformer system according to claim 4, 5 or 6, characterised in that first latching means are provided through which the evaluation electronics compartment and the current transformer compartment can be retained in the disconnect position and/or the contact position, so that the evaluation electronics compartment and the current transformer compartment can only be moved from this position if the latching means are elastically deformed.
8. The current transformer system according to one of the claims 4 to 7, characterised in that second latching means are provided through which the evaluation electronics compartment and the current transformer compartment can be retained in the contact position, so that the evaluation electronics compartment and the current transformer compartment can only be moved from the contact position if the second latching means are released.
9. The current transformer system according to claim 8, characterised in that the system housing is provided with a connecting space that is attached to the current transformer compartment, in which connecting means are disposed for connecting a power conductor, wherein the connecting space is provided with a connecting space cover on which the second latching means are arranged.
10. The current transformer system according to one of the claims 1,2 to 9, characterised in that the separating device is a plug connection.
11. NH fuse rail or NH fuse switch comprising a housing with a base plate and at least one supply terminal, which preferably protrudes over the base plate, and at least one output terminal as well as at least one fuse, which when inserted connects the supply terminal with the output terminal, characterised in that a current transformer system according to one of the claims 1 to 10 is provided.
12. The NH fuse rail or NH fuse switch according to claim 11, characterised in that the current transformer is arranged such that it surrounds the output terminal.