AU2012396428B2

AU2012396428B2 - Current transformer and load interrupter having such a current transformer

Info

Publication number: AU2012396428B2
Application number: AU2012396428A
Authority: AU
Inventors: Ludger Sandhager; Martin Schroder
Original assignee: EFEN GmbH
Current assignee: EFEN GmbH
Priority date: 2012-12-13
Filing date: 2012-12-13
Publication date: 2017-01-05
Anticipated expiration: 2032-12-13
Also published as: AU2012396428A1; HK1211704A1; CN104871013A; BR112015013818A2; WO2014090319A1; CN104871013B

Abstract

The present invention relates to a current transformer system having a current transformer, which detects a current flowing through the current transformer and converts said current into a measurement voltage, and evaluation electronics which, on the basis of the measurement voltage, determine at least one of the characteristic variables from the group G consisting of I, I

Description

1 2012396428 21 Nov 2016

Current transformer and load interrupter having such a current transformer

The present invention concerns NH fuse switch disconnectors or NH 5 fuse switch rails having a housing with a bottom surface and at least one feed-in contact and at least one outgoing contact.

Such voltage high-power (NH) fuse switch disconnectors or NH fuse switch rails have long been known and serve to provide secured outlets of busbars which can be separated under load. The devices generally have 10 one or more lower fuse parts which are arranged in the housing. Corresponding fuse inserts are mounted for example on a switching cover so that, when the switching cover is closed, the fuse inserts are fitted into the lower fuse parts and make a connection between the respective feed-in contacts - which can be connected to the busbars - and the outgoing 15 contacts. When the switching cover is opened the fuse inserts are pulled out of the lower fuse parts so that the connection is interrupted.

In principle the present invention can also be used in relation to open distributor bars in which the fuse inserts can be pulled out of the open housing with a suitable tool. The term NH fuse switch rail is therefore also 20 intended to embrace the open distributor bars.

For many purposes of use measurement of the current flow by way of the provided outlet is desired. Current transformers are generally used for that purpose. Current transformers operate like transformers, that is to say an alternating current flowing through the outgoing connection 25 (primary conductor) induces in a secondary conductor afforded by the current transformer a secondary current which is galvanically separated from the primary circuit and which can be evaluated to measure the primary current. Thus measurement is effected in contact-less manner.

For example plug-on window type current transformers are known 30 which have a primary conductor (for example in the form of an electrically conductive cylinder portion) and a secondary conductor surrounding same. Upon fitment the current transformer is mounted on the feed-in contact so 11905953 2012396428 21 Nov 2016 2 that the primary conductor contacts the feed-in contact and the primary conductor of the current transformer receives the current flowing through the feed-in contact.

What is common to the known current transformer systems is that 5 the connection of the secondary conductor to corresponding evaluation devices is laborious as each current transformer must be connected by means of two connecting cables and at the same time shortcircuit-proof cabling is to be guaranteed.

Therefore, for the above-mentioned NH fuse switch rails it has 10 already been proposed in DE 10 2007 051 419 that a current transformer module comprising three different current transformers which are respectively linked to a feed-in contact are provided at the underside of the housing. However even with that structure if required a corresponding electronic evaluation device with a display device is to be respectively 15 connected to the desired current transformer. Evaluation devices and in particular display devices are costly and cannot be fitted in the switching cabinets but are only connected if required to the corresponding current transformer.

In any case however it is necessary for a technician on site to 20 connect the current transformer to the evaluation and display device in order to establish how much current is being taken off by way of the corresponding outlet. The known structures also only allow the display of a single parameter like for example the detected current strength. The display of other parameters is either not possible or is only possible as an 25 alternative so that it is not possible to implement simultaneous monitoring of a plurality of parameters.

Taking the described state of the art as the basic starting point an object of the present invention is to provide an NH fuse switch disconnector or an NH fuse switch rail of the kind set forth in the opening part of this 30 specification, which easily allows the relevant parameters to be ascertained, or to substantially ameliorate one or more disadvantages or the existing arrangements. 2012396428 21 Nov 2016 3

Disclosed in one aspect is a current transformer system comprising a current transformer with which the current flowing from the feed-in contact to the outgoing contact can be detected and converts it into a measurement voltage, and an electronic evaluation means which on the 5 basis of the measurement voltage ascertains at least one of the parameters from the group G comprising I, ln, L, Lin, Itr, Lax, U, Un, f, fn and PF, wherein I = electric current flowing through the current transformer, ln = specified reference current strength for which the current transformer was designed, lst = lowest specified value of I, at which the current transformer 10 measures an electrical active energy at a power factor of one, Lin = value of I, above which the deviation is within the error limits, l,r = value of I, above which the deviation is within the lowest error limits which correspond to the accuracy class specified for the current transformer system, Lax = highest value of I at which the deviation is within the error limits, U = 15 electric voltage at the current transformer, Un = specified reference voltage, f = frequency of the voltage at the current transformer, fn = specified reference frequency, and PF = power factor = coscp = cosine of the phase shift φ between I and U.

In other words the current transformer system not only has the 20 actual current transformer but at the same time an electronic evaluation means which determines at least one of the parameters from the group G.

In a preferred embodiment the electronic evaluation means ascertains at least two of the parameters from the group G and at the best all of said parameters. 25 The current transformer system can preferably have a bus system connecting terminal, by way of which the current transformer system can be connected to a bus system so that the ascertained parameters can be transmitted by way thereof.

It is thus possible for the fuse switch load disconnector and the fuse 30 switch rail to be connected to a bus system so that the corresponding parameters can be read out by way of a computer which is also connected to the bus and which for example can be arranged at the energy provider 2012396428 21 Nov 2016 4 and therefore does not necessarily have to be arranged in the proximity of the switching cabinet. In that way it is possible to simultaneously monitor a plurality of parameters over a longer period of time without the presence of a technician being required. 5 Particularly when a plurality of disconnectors or rails are to be monitored each NH fuse switch disconnector or each NH fuse switch rail and at best each outgoing contact of the fuse switch disconnector or fuse switch rail advantageously has associated therewith its own identification address so that, at a remote location, for example at the energy provider, the 10 characteristic parameters for each individual outgoing contact can be easily detected without the need for a technician on site to temporarily connect the corresponding electronic evaluation means.

Alternatively or in combination it is also possible for the current transformer system to have a connection for a display device. The display 15 device can then represent the corresponding parameters on a display. It will be appreciated that the connection for a display device must not only communicate the ascertained parameters but must also provide the energy supply for the display device. In that way if necessary a technician on site can also read out the desired parameters. 20 In a further preferred embodiment the current transformer system even has a display device for displaying the ascertained parameters so that there is no need to connect a corresponding display.

In addition it has been found that the current transformer is to be arranged as much as possible surrounding the outgoing contact as it is here 25 that the corresponding bus system and possibly a display device can be easily connected. In other words the outgoing contact - or an element connected directly thereto - serves as a primary conductor for the current transformer.

The current transformer system is either accommodated in the 30 housing of the fuse switch disconnector or the fuse switch rail or it has its own housing in which the individual components of the current transformer system are accommodated. In addition it is also possible for the current 2012396428 21 Nov 2016 5 transformer system to be arranged partially in the housing of the fuse switch disconnector and partially in its own housing or for the current transformer system to be arranged in two separate housings. For example the actual current transformer could be arranged in a housing separate 5 from the electronic evaluation means, in which case then the two housings, that is to say the housing of the current transformer and the housing of the electronic evaluation means have to be connected together. That can be effected for example by suitable connecting contacts.

In a preferred embodiment there is provided a triggering monitoring 10 means for the at least one fuse insert, which is preferably also arranged in the housing. The triggering monitoring means can also be read out by way of the bus connection.

According to another aspect, there is disclosed an NH fuse switch disconnector having a housing with a bottom surface and at least one feed-15 in contact which projects beyond the bottom surface and at least one outgoing contact, and at least one fuse insert which in an inserted condition connects the feed-in contact to the at least one outgoing contact, wherein there is provided a current transformer system comprising a current transformer which detects a current flowing through the current 20 transformer and converts the detected current into a measurement voltage, and an electronic evaluation means which on the basis of the measurement voltage ascertains at least one of the parameters from the group G comprising I, ln, lsl, lmin, ITR, Imax, U, Un, f, fn and PF, wherein I = electric current flowing through the current transformer, ln = specified reference 25 current strength for which the current transformer was designed, ls, = lowest specified value of I, at which the current transformer measures an electrical active energy at a power factor of one, lmin = value of I, above which the deviation is within the error limits, l,r = value of I, above which the deviation is within the lowest error limits which correspond to the 30 accuracy class specified for the current transformer system, lmax = highest value of I at which the deviation is within the error limits, U = electric voltage at the current transformer, Un = specified reference voltage, f = 5a 2012396428 21 Nov 2016 frequency of the voltage at the current transformer, fn = specified reference frequency, and PF = power factor = coscp = cosine of the phase shift φ between I and U, wherein the current transformer is arranged surrounding the at least one outgoing contact. 5

According to another aspect, there is disclosed an NH fuse switch rail having a housing with a bottom surface and at least one feed-in contact which projects beyond the bottom surface and at least one outgoing contact, and at least one fuse insert which in an inserted condition connects 10 the feed-in contact to the at least one outgoing contact, wherein there is provided a current transformer system comprising a current transformer which detects a current flowing through the current transformer and converts the detected current into a measurement voltage, and an electronic evaluation means which on the basis of the measurement voltage 15 ascertains at least one of the parameters from the group G comprising I, ln, 1st, Imin, Itr, I max, U, Un, f, fn and PF, wherein I = electric current flowing through the current transformer, ln = specified reference current strength for which the current transformer was designed, ls, = lowest specified value of I, at which the current transformer measures an electrical active energy 20 at a power factor of one, lmin = value of I, above which the deviation is within the error limits, l,r = value of I, above which the deviation is within the lowest error limits which correspond to the accuracy class specified for the current transformer system, lmax = highest value of I at which the deviation is within the error limits, U = electric voltage at the current 25 transformer, Un = specified reference voltage, f frequency of the voltage at the current transformer, fn = specified reference frequency, and PF = power factor = coscp = cosine of the phase shift φ between I and U, wherein the current transformer is arranged surrounding the at least one outgoing contact. 30 In that way it is now possible even from a remote location, for example at the location of the energy provider, to establish which fuse insert has triggered so that a search for the fault is markedly simplified. 11905953 2012396428 21 Nov 2016 5b

Further advantages, features and possible uses will be clearly apparent from the description hereinafter of a preferred embodiment and the related Figures in which:

Figure 1 shows a diagrammatic view of an NH fuse switch 5 disconnector with the current transformer system according to the invention,

Figure 2 shows a sectional view of a housing of a first current transformer system according to the invention, and

Figure 3 shows a sectional view of housings of a second current 10 transformer system according to the invention.

Figure 1 shows a diagrammatic view of an NH fuse switch disconnector 1. It has a housing 2 in which three fuse inserts 3, 3' and 3" are arranged. At its underside it is possible to see three outgoing contacts 4, 5, 6 as well as a current transformer block 9 which is fixed to the 15 underside of the disconnector in such a way that the outgoing contacts extend through same. The current transformer system 9 has a connection 8 with which the transformer system can be connected to a bus system, that is to say a data transmission system. The embodiment also has a display device 7 which is capable of displaying the ascertained parameters. 20 6

Figure 2 shows a sectional view through the current transformer system of Figure 1. The housing 2 has a through opening 10 for receiving the corresponding outgoing contact. In addition Figure 2 shows an outgoing terminal 11, 12, the lower part 11 of which is in electrical contact with the 5 outgoing contact fitted into the through opening 10. The upper part 12 can be moved in the direction of the first part 11 by means of the screw 13 so that a corresponding cable which is to be fixed to the outgoing contact can be clamped between the two parts 11 and 12. The housing has a chamber 14 in which the corresponding electronic evaluation means can be placed. 10 Figure 3 shows an alternative embodiment. A substantial difference in relation to the embodiment shown in Figures 1 and 2 is that the electronic evaluation means 15 is now no longer disposed in the housing portion 14 but in a separate housing. Provided at the top side of the housing of the electronic evaluation means 15 is a metal contact block 19. 15 The current transformer 16 which surrounds a busbar 17 is connected to a connecting contact 18. The connecting contact 18 is biased resiliently on to the connecting block 19 so that there is an electrical connection between the electronic evaluation means 15 on the one hand and the current transformer 16 on the other hand. With this embodiment it is now possible 20 to exchange either the electronic evaluation means 15 or the current transformer housing without the respective other part having to be removed. 7

List of references 1 NH fuse switch disconnector 2 5 3, 3', 3" 4 5 6 7 10 8 9 10 11 12 15 13 14 15 16 17 20 18 19 housing fuse inserts outgoing connection outgoing connection outgoing connection display device connection housing through opening outgoing terminal outgoing terminal screw chamber electronic evaluation means current transformer busbar connecting contact connecting block

Claims

1. An NH fuse switch disconnector having a housing with a bottom surface and at least one feed-in contact which projects beyond the bottom surface and at least one outgoing contact, and at least one fuse insert which in an inserted condition connects the feed-in contact to the at least one outgoing contact, wherein there is provided a current transformer system comprising a current transformer which detects a current flowing through the current transformer and converts the detected current into a measurement voltage, and an electronic evaluation means which on the basis of the measurement voltage ascertains at least one of the parameters from the group G comprising I, ln, Lt, Lin, I tr, I max, U, Un, f, f„ and PF, wherein I = electric current flowing through the current transformer, ln = specified reference current strength for which the current transformer was designed, 1st = lowest specified value of I, at which the current transformer measures an electrical active energy at a power factor of one, I min = value of I, above which the deviation is within the error limits, Itr = value of I, above which the deviation is within the lowest error limits which correspond to the accuracy class specified for the current transformer system, lmax = highest value of I at which the deviation is within the error limits, U = electric voltage at the current transformer, Un = specified reference voltage, f = frequency of the voltage at the current transformer, fn = specified reference frequency, and PF = power factor = coscp = cosine of the phase shift φ between I and U, wherein the current transformer is arranged surrounding the at least one outgoing contact.

2. An NH fuse switch disconnector according to claim 1 wherein there are provided three feed-in contacts and three outgoing contacts and the current transformer system has three current transformers, wherein each current transformer is arranged surrounding a respective one of the outgoing contacts.

3. An NH fuse switch disconnector according to claim 1 or 2 wherein there is provided a triggering monitoring means for the at least one fuse insert, wherein the current transformer system has a transformer housing in which the at least one fuse insert is accommodated.

4. An NH fuse switch disconnector according to claims 1 to 3 wherein the electronic evaluation means ascertains at least two of the parameters from the group G.

5. An NH fuse switch disconnector according to one of claims 1 to 4 wherein the current transformer system has a bus system connection terminal, by way of which the current transformer system can be connected to a bus system and the ascertained parameters can be transmitted.

6. An NH fuse switch disconnector according to one of claims 1 to 5 wherein there is provided a connection for a display device.

7. An NH fuse switch disconnector according to one of claims 1 to 6 wherein there is provided a display device for displaying the ascertained parameters.

8. An NH fuse switch disconnector according to one of claims 1, 2, 4 to 7 when not dependent on claim 3 wherein the current transformer system has a transformer housing in which the individual components of the current transformer system are accommodated.

9. An NH fuse switch disconnector according to claim 3, wherein the individual components of the current transformer system are accommodated in the transformer housing.

10. An NH fuse switch rail having a housing with a bottom surface and at least one feed-in contact which projects beyond the bottom surface and at least one outgoing contact, and at least one fuse insert which in an inserted condition connects the feed-in contact to the at least one outgoing contact, wherein there is provided a current transformer system comprising a current transformer which detects a current flowing through the current transformer and converts the detected current into a measurement voltage, and an electronic evaluation means which on the basis of the measurement voltage ascertains at least one of the parameters from the group G comprising I, ln, lst, lmin, lTR, I max, U, Un, f, fn and PF, wherein I = electric current flowing through the current transformer, ln = specified reference current strength for which the current transformer was designed, lst = lowest specified value of I, at which the current transformer measures an electrical active energy at a power factor of one, lmin = value of I, above which the deviation is within the error limits, Itr = value of I, above which the deviation is within the lowest error limits which correspond to the accuracy class specified for the current transformer system, Lax = highest value of I at which the deviation is within the error lim its, U = electric voltage at the current transformer, Un = specified reference voltage, f = frequency of the voltage at the current transformer, fn = specified reference frequency, and PF = power factor = coscp = cosine of the phase shift φ between I and U, wherein the current transformer is arranged surrounding the at least one outgoing contact.

11. An NH fuse switch rail according to claim 10 wherein there are provided three feed-in contacts and three outgoing contacts and the current transformer system has three current transformers, wherein each current transformer is arranged surrounding a respective one of the outgoing contacts.

12. An NH fuse switch rail according to claim 10 or 11 wherein there is provided a triggering monitoring means for the at least one fuse insert, wherein the current transformer system has a transformer housing in which the at least one fuse insert is accommodated.

13. An NH fuse switch rail according to claims 10 to 12 wherein the electronic evaluation means ascertains at least two of the parameters from the group G.

14. An NH fuse switch rail according to one of claims 10 to 13 wherein the current transformer system has a bus system connection terminal, by way of which the current transformer system can be connected to a bus system and the ascertained parameters can be transmitted.

15. An NH fuse switch rail according to one of claims 10 to 14 wherein there is provided a connection for a display device.

16. An NH fuse switch rail according to one of claims 10 to 15 wherein there is provided a display device for displaying the ascertained parameters.

17. An NH fuse switch rail according to one of claims 10, 11, 13 to 16 when not dependent on 12 wherein the current transformer system has a transformer housing in which the individual components of the current transformer system are accommodated.

18. An NH fuse switch rail according to claim 12, wherein the individual components of the current transformer system are accommodated in the transformer housing.