EP2883235A1

EP2883235A1 - Current transformer having an automatic short-circuit device

Info

Publication number: EP2883235A1
Application number: EP13745854.3A
Authority: EP
Inventors: Dat-Minh Trinh; Markus Becker
Original assignee: Phoenix Contact GmbH and Co KG
Current assignee: Phoenix Contact GmbH and Co KG
Priority date: 2012-08-08
Filing date: 2013-08-07
Publication date: 2015-06-17
Also published as: WO2014023785A1; CN104541343A; DE102012107277A1; US20150206650A1; DE102012107277B4; US9349527B2

Abstract

The invention relates to a current transformer (1), comprising connection contacts (3) for contacting a secondary winding of the current transformer and a short-circuit device (105, 205, 305) for shorting the connection contacts (3), wherein the connection contacts (3) can be reached through a housing opening (4) of a housing (2) surrounding the current transformer (1), the current transformer also having a safety device (107, 207, 307) for blocking the access to the connection contacts (3) lying inside the housing (2), wherein the safety device (107, 207, 307) can be in a securing status or a release status, and wherein the access to the connection contacts (3) is blocked by the safety device (107, 207, 307) in the securing status, such that the connection of a conductor to a connection contact (3) and the disconnection of a conductor from a connection contact (3) are not possible, and wherein the access to the connection contacts (3) is released by the safety device in the release status and the short-circuit device (105, 205, 305) shorts the connection contacts (3) in the release status, such that the connection of a conductor to a connection contact (3) or the disconnection of a conductor from a connection contact (3) are possible.

Description

Current transformer with automatic short circuit device

The invention relates to a current transformer with an automatic short-circuiting device, with which the

Secondary winding of the current transformer is automatically short-circuited after unlocking a safety device, such as tamper protection.

Current transformers are mostly used to measure alternating currents and work on the principle of the Rogowski coil. In this case, an alternating current flowing in a primary coil or in a primary conductor induces a

electric current in a generally annularly arranged secondary coil. Often, the primary coil has very little or only one winding relative to the secondary coil, which is that the primary conductor is passed through the secondary coil. In this case one speaks of a Aufsteck- or

Through transformers. The induced current in the secondary winding is in height dependent on the number of

Secondary windings and substantially proportional to the inducing primary current. It is therefore very well suited as a measuring or manipulated variable. In contrast to the Rogowski coil, a current transformer has a mostly toroidal ferromagnetic core, which has a high magnetic field due to the bundling of the magnetic field

Efficiency and high accuracy in terms of proportionality between primary and secondary current ensured.

Due to the high efficiency by a

Current transformer generates high enough secondary currents that These are suitable directly and without further reinforcement for the control ^¬ or regulation of other circuit components.

However, this has the disadvantage that a

Secondary circuit of a current transformer must never be operated open, otherwise the very high ("infinite")

Resistance between the open secondary terminals leads to very high voltages between them. These would not only pose a danger to humans, but also lead to flashovers and breakdowns that can destroy the current transformer.

An advantage of current transformers is the galvanic separation of primary and secondary current. This is the

Secondary circuit independent of the potential of the primary circuit. So there are basically potential free

Modifications of the secondary circuit possible without a potential-related primary circuit would have to be turned off.

There is therefore motivation, for example in

Power supply facilities to be able to make modifications to a circuit of the secondary circuit at a primary side in operation current transformer without the current transformer by an interim

Breakage of the secondary circuit is destroyed.

This goal can be achieved by the secondary circuit of the current transformer before disconnecting connecting conductors

temporarily shorted. This can

for example, by an external jumper or even via a specially provided for the current transformer, built-in short circuit device done. In order to reduce the risk of incorrect operation by humans, solutions are already known from the prior art, which provide an automatic shorting of the secondary circuit, as soon as the

Connection connections to the current transformer are solved.

Thus, in US 2009/0186504 AI describes a connection system for a current transformer, in which a plug contact in addition to the electrical contacts additionally has a pin whose removal short-circuiting the

Secondary contacts causes.

Furthermore, DE 16 13 706 B describes a

Short circuit device for the secondary circuit of a

Current transformer, which also leads to the removal of a pin associated with a plug pin for shorting the short-circuiting device.

However, to enable closing or opening of the short-circuiting device, both solutions require

circuit side specially trained plug contacts.

The object of the invention is to provide a current transformer with an improved automatic short-circuit device

which allows a direct connection of conductors to the current transformer.

The object is achieved by the features of the subject matter of claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

The invention thus provides a current transformer with connection contacts for contacting his Secondary winding, which can be reached via a housing opening of the housing surrounding the current transformer, wherein the current transformer is a short-circuit device for

Short circuiting of the terminal contacts and the

Short circuit device comprises a mechanically movable conductor, which can be brought into a circuit between the terminals of the secondary winding, which includes a safety device for blocking access to the inside of the housing

Having connection contacts, which is located in a

Backup status or release status, with access to the contacts through the

Safety device is blocked in the backup status, so that connecting a conductor to a

Connecting contact or disconnecting a conductor from a connection contact is not possible

and access to the connectors through the

Safety device is enabled in the release status and the short-circuiting device short-circuits the terminals in the release status, so that a connection of a conductor to a terminal contact or a separation of a conductor from a terminal contact is possible.

The advantages of this solution are that the

Connection contacts must have no special requirements for a packaging of the conductor to be connected and at the same time the safety device in

Interaction with the short circuit device reduces the risk of incorrect operation.

The connection contacts can be designed so that stripped conductors can be contacted directly.

The contacts can so for example as

Screw or terminal contacts may be formed, which are to be operated via a housing opening. Access to the terminals is access to the connection or actuation mechanism of

Understand terminal contacts.

With a blocking of access to the terminals, the security device thus provides in the normal

Operating mode - in which the safety device is in the fuse state - sure that proper disconnection of connected conductors is not possible.

In other words, a connection or disconnection of conductors from the terminals of the secondary winding is only possible if previously the safety device has been unlocked or brought into a release status. In this release status, the secondary connections of the

Current transformer via the short-circuit device automatically short-circuited.

It is therefore not possible to have a leader of one

Disconnect the terminal of the secondary winding without operating the safety device and thus automatically short circuit the secondary circuit of the CT.

Advantageously, the safety device can be designed as a cover sleeve which can be inserted into the housing in such a way that it provides access to the connection contacts

blocked while the short-circuit device opens.

Such a cover sleeve may be formed from a preferably flat piece of insulating material. Such a cover sleeve can be inserted through a slot in the housing and can do equally two tasks fulfill. On the one hand, it can close the housing opening as access to the connection contacts with a corresponding geometric configuration. On the other hand, it can open the shorting device by itself

isolating between two contacts of the shorting device slides.

In this case, the cover sleeve may be formed in one or more parts, wherein it is not excluded that even a one-piece cover sleeve closes a plurality of housing openings to several connection contacts simultaneously.

Therefore, the short-circuit device is advantageous as

Formed switch over which the circuit between the terminal contacts as described above in the fuse status of the cover is separable.

Advantageously, short circuit device is so

designed in such a way that it has a spring-loaded conductor, via which the electric circuit between the connection contacts can be closed, the connection contacts one each

Have short-circuit contact or with such

are electrically connected, the cover sleeve is formed of insulating material and the cover between the spring-loaded conductor and the short-circuit contact is inserted insulating, so that the circuit between the terminal contacts is interrupted.

Such an arrangement has only a few components and offers great freedom and adaptability with regard to the geometric design. In another advantageous embodiment of the invention, the safety device may be designed as a flap mechanism. Such a flap mechanism advantageously has an insulating separating element and flaps, by means of which the access to the connecting contacts can be closed in the security status, the short-circuiting device being protected by the insulating separating element

is interruptible and the flaps and the separating element are mechanically coupled so that the flaps in

Backup status are locked and the

Short circuit device is separated by the separating element, and the flaps are open in the release status and the short-circuiting device short-circuits the terminals.

Such a flap mechanism has the advantage that safety device and current transformer are not designed in several parts, but the safety device is integrated in the current transformer.

In this case, furthermore, the opened flaps can advantageously protrude out of the current transformer, so that the status of the safety device is clearly visible, as a result of which

Danger of being accidentally short-circuited

State remaining short circuit device is reduced.

Advantageously, the short-circuit device of the second embodiment as a mechanically movable conductor to a spring-loaded conductor over which the circuit between the terminal contacts can be closed, wherein the

Connection contacts each have a short-circuit contact

have or with such an electrically conductive

are connected and the separating element between the sprung Conductor and the short-circuit contacts insulating insertable, so that the power circuit between the

Connection contacts is interrupted. The advantage of such an embodiment is that the flap mechanism has several movable elements

one of which can be formed as a separating element, so that the same movement which opens or closes the flaps over the separating element

Shorting device can close or open.

The moving elements of the flap mechanism,

in particular separating element and flaps are doing

advantageously mechanically coupled by a hinge mechanism.

Thus, the movement which opens or closes the flaps can be deflected in different directions. This allows great freedom in terms of

Embodiment for the position and the direction of movement of the separating element as well as the separable from him

Isolating contact.

In this case, a removal of the separating element causes a

Transition from the backup status to the release status.

In principle, however, is also possible in the reverse manner, the flap mechanism with a closing contact

connect, which is closed for example by a pressure element, as soon as the flaps allow access to the terminal contacts.

Further advantageously, the separating element is provided with lateral arms which are movable on one side with a Flap are connected so that a distal removal of the separating element causes a lifting of the flaps.

The lateral arms offer the advantage that a pulling force acting on the separating element at points can be transmitted to the individual flaps via the arms. An action of a tensile force on the separating element can thus cause an opening of several or all flaps.

Advantageously, the current transformer is designed so that a guide mechanism allows sliding of the flaps in one-sided lifting.

Such a guide mechanism has the advantage that a lifting movement is converted into a rotational movement.

While a mere lifting movement would only result in lifting of the flaps, the guide mechanism will cause the flaps to rotate, exposing the housing opening in a manner that permits insertion of a tool for loosening or securing conductors to the terminals.

Advantageously, the current transformer is therefore still so

designed that the housing openings over which the

Terminal contacts are reachable, at their edges

at least partially guide rails or guide grooves having flaps on one side of a guide pin which lies in the guide rail or guide groove and is slidable in this, so that the flaps slide in a one-sided lifting guided over the guide mechanism. In a further advantageous embodiment of the invention, the safety device can be displaced

Contact cover be formed. In this case, the safety device is designed as a contact cover, which can be pushed or closed by moving, and which closed in the backup status access to a terminal contact in

Backup status blocked.

Furthermore, it releases the access to the connection contact in the release status. It is the

Short circuit device, which has a sliding contact as a mechanically movable conductor, with the

Contact cover coupled so that by moving the contact cover, the short-circuiting device can be opened or closed.

The advantage of this design is that even this design as a current transformer with

Short-circuit device and safety device is executable in one piece and it also makes no high demands in terms of height, since the height in the backup status as in the release status, or at

closed as with open shorting device is the same.

Advantageously, the contact cover in the fuse status is inserted into the housing of the current transformer.

The displaceability of the contact cover brings not only the advantage of a low height with it, but also that the area above the housing opening for a tool easily accessible remains free. Advantageously, a contact cover of a

Terminal contacts are pushed individually, the terminal contacts of the secondary coil via each contact cover are short-circuited via a respective short-circuiting device.

This will be a very small construction of

Safety device as well as short circuit device

allows, as the space area, in the one

Contact cover is pushed in to open,

can be used alternately by different contact covers.

Because through each contact cover a respective

Short circuit device is actuated, the secondary coil of the current transformer is also shorted when only one of the contact covers is opened.

Advantageously, the contact cover and the

Sliding contact rigidly connected or formed as an element, so that a closing of the

Sliding contact causes a sliding of the contact cover. This design allows a very space-saving and mechanically robust arrangement, as opened according to the principle of a slide switch one contact and another is closed. Advantageously, the sliding contact latching lugs on the safe closing of the sliding contact and the

Cause and / or indicate short circuit device. A noticeable locking of the detents may also indicate that the contact cover has reached its target position. This is advantageously chosen so that the sliding contact of the short-circuiting device is securely closed.

In addition, the detents keep the sliding contact reliably closed, so that accidental, possibly even only partial sliding apart of the sliding contact with the possible consequence of the destruction of the current transformer can be prevented.

The invention will be explained in more detail with reference to the accompanying drawings with reference to preferred embodiments.

Show it

Fig. La a first embodiment of an inventive

Current transformer with shorted

Short circuit device in perspective

Representation with partially open housing head,

Fig. Lb a first embodiment of an inventive

Current transformer with open short-circuit device in perspective with partially open housing head,

Fig. 2a shows a second embodiment of an inventive

Current transformer with open short-circuit device in perspective view with complete housing, Fig. 2b shows a second embodiment of a current transformer according to the invention with short-circuited

Short circuit device

(perspective view with complete housing)

Fig. 2c shows a second embodiment of an inventive

Fig. 2d, a second embodiment of an inventive

Current transformer with shorted

Short circuit device in perspective

Representation with partially open housing head,

Fig. 3a shows a third embodiment of an inventive

Current transformer with open short-circuit device in perspective view with complete housing,

Fig. 3b shows a third embodiment of an inventive

Fig. 3c, a third embodiment of an inventive

Current transformer with closed

Short circuit device with left open contact cover in perspective view with partially open housing head,

Fig. 3d shows a third embodiment of an inventive

Current transformer with open short-circuit device in perspective with open

Housing head and

3e a security device of a third

Embodiment of a current transformer according to the invention in a perspective view.

The following are all views without screws

shown.

The figure la shows a first embodiment of a

The current transformer 1 according to the invention, the short-circuit device 105 with a short-circuit contact 108 is located in one

short-circuited position and the housing head is half removed for clarity.

The lower, in the projection square part of the

Housing 2 comprises a secondary winding with a

ferromagnetic core. The central opening of the housing 2 serves to pass through a primary conductor, wherein the

Profile of the opening is suitable to accurately record busbars in common, standardized formats.

The upper part of the housing 2 includes as housing head the connection contacts 3 of the current transformer 1, with which the ends of the secondary winding, not shown here, are electrically connected.

In the area of the connection contacts 3, the housing head has lateral and end openings, the lateral openings of the supply of connection conductors and the front housing openings 4 serving to operate the connection contacts 3. The short-circuit device 105 of the embodiment of the invention shown in FIG. 1 is closed; the resilient conductor 106 contacts the connection contacts 3 on both sides of the short-circuit contact 108 and thus closes the connection

Electric circuit between the connection contacts 3.

FIG. 1a also shows two safety devices 107 in the form of cover sleeves 107. These are flat and have an angle profile, so that they can cover the connection contacts 3 from two sides. For this purpose, they are laterally inserted into the housing 1, wherein the housing 1 to this - not visible here - provides appropriate slots. Figure lb shows the same embodiment of a

inventive current transformer 1 with open

Shorting device 105. The cover sleeves 107 are inserted into the housing 2 on both sides. Through her

Angle profile are the cover sleeves 107, the

Cover contacts 3 both from above and laterally separated from the spring-loaded conductor 106.

The cover sleeves 107 close the housing opening 4 and thus the access to the connection contacts 3. Furthermore, they are inserted in insulating manner between the connection contacts 3 and the spring-loaded conductors 106.

Figure 2a shows a second embodiment of the invention. It is a perspective view, wherein the housing 2 is shown completely closed.

The hidden by the housing 2 bobbin with the

Secondary coil corresponds to that of the first embodiment of the invention. Likewise, the embodiment of the terminal contacts 3 corresponds to that of the first embodiment, wherein a part of

Connection contacts 3 can be seen on the side openings for the supply of connecting conductors.

At the front, the current transformer 1 has two flaps 207, of which the underlying connection contacts. 3

to be covered. The flaps 207 are with a

Separator 209 mechanically connected. The separating element 209 has an eyelet for operation. At the same time, the eyelet for fixing a wire seal - not shown here - suitable. In connection with a second eyelet on the housing 2

attached eyelet or a suitable housing opening, the separator 209 can be secured against unauthorized operation. Figure 2b shows the same embodiment of a

inventive current transformer 1, wherein the separating element 209 away from the current transformer 1, in the illustration, was moved. The flaps 207 give the

underlying housing openings 4 free, so that the connection contacts 3 are accessible.

The flaps 207 on the arms 210 of the

Separator 209 rotatably mounted, so that the flaps 207 are not raised vertically, but in the

Fold down presentation and thus the

Expose housing opening 4. Figure 2c shows the same embodiment of the current transformer 1, wherein the housing head for better

Representation is half removed. The flaps 207 closed in FIG. 2c have, at their outer corners, a guide pin 211 which is located in a guide groove below the housing opening 4

is displaceable, so regardless of one

Installation orientation (also on the side or upside down)

Unfold the flap 207 in a vertical train.

Furthermore, FIG. 2 c shows the interruption of the contacts between the terminal contacts 3 and the spring-loaded conductor 206 through the separating element 209.

FIG. 2d shows the same representation when opened

Flaps 207 and closed short-circuiting device 205. The flaps 207 are folded out in the groove and give access to the connection contacts 3 free. The separator 209 has been removed between the terminal contact 3 and the spring-loaded conductor 206, so that the spring-loaded conductor 206 the terminal contact 3 at its

Short-circuit contact 208 contacted and thus the

Shorting device 205 closes.

Figure 3a shows a third embodiment of the invention. It is a perspective view, wherein the housing 2 is shown completely closed. The hidden by the housing 2 bobbin with the

At the front, the current transformer 1 housing openings 4, which as access to the actuators of

Terminal contacts 3 but in the figure 3a of the

Safety device 307 are closed.

FIG. 3b shows a design of the safety device 307 as a displaceable contact cover 307. This has a sliding arm, which can be actuated by a corresponding opening of the housing 2 from the outside. Further, the contact cover 307 is connected to the movable conductor 306. The movable conductor 306 is formed as a sliding contact 306 and on

Short-circuit contact 308 with the terminal contacts 3 conductively connected. He continues to be in contact with the terminal contact 3 of the other terminal contact 3 of the secondary coil, so that the power circuit between the terminal contacts 3 of the secondary coil on the

Sliding contact 306 is closable. Figure 3c shows the same embodiment of the

Current transformer with half removed housing head. A contact cover 307 is parallel to the surface of the

Housing 2 is moved in the direction of the longitudinal axis of the current transformer, allowing access to the corresponding

Connection contacts 3 via the housing opening 4 is accessible. At the same time, the slide contact 306 connected to the contact cover 307 contacts the other one

Terminal 3 at the shorting contact 308, so that the Electric circuit between the terminals 3 of the

Secondary terminals is closed.

Meanwhile, the second contact cover 307 is

closed. Depending on the available space between the terminals 3, training is also possible such that the second contact cover 307 is to be opened simultaneously. If the contact covers 307 lie in one plane, this is possible if the available space between the access points to the connection contacts 3 is at least equal to the common width of the two in its width

Contact covers 307 corresponds.

FIG. 3d shows the same embodiment of the invention

Current transformer 1 with the housing head open and closed contact covers 307. It can be seen that the contact covers 307 and the associated

Sliding contacts 306 are formed symmetrically to each other and each contact cover 307 can close a short-circuit device 305 by means of a sliding contact 306.

Furthermore, it can be seen that both contact covers lie in one plane.

This property is beneficial to the two

Contact covers 307 to lock easily via locking lugs 312 with each other.

FIG. 3 e shows a corresponding embodiment of FIG

Contact cover 307. In this case, the contact cover on the side arranged locking lugs 312, which are adapted to lock two symmetrically formed contact covers 307 along the displacement axis in different positions. The illustration shows two locking lugs, which are suitable, the contact covers 307 in two Lock positions. This is in the illustrated embodiment, on the one hand, the position in which only one of the contact covers 307 is opened and, secondly, the position in which both contact covers 307 are closed. Basically, the contact cover 307 - not shown here - have a third locking lug for locking in a third position, in which both

Contact covers 307 are opened.

FIG. 3 e further shows that the safety device 307 in the form of the contact cover 307 in this embodiment is rigidly connected to the sliding contact 306.

Reference sign list

Current transformer 1

Housing 2

Connection contact 3

Housing opening 4

Short circuit device 105, 205, 305 movable conductor 106, 206, 306

Sprung ladder 106, 206

Sliding contact 306

Security device 107, 207, 307

Covering sleeve 107

Flap 207

Contact cover 307

Short-circuit contact 108, 208, 308

Separating element 209

Arm 210

Guide pin 211

Latch 312

Claims

claims

1. Current transformer (1) with connection contacts (3) for

Contact his secondary winding, which has a

Housing opening (4) of the current transformer (1) surrounding the housing (2) can be reached, wherein the current transformer (1) has a short circuit device (105, 205, 305) for

Short circuiting of the terminal contacts (3) and the short-circuiting device (105, 205, 305) has a mechanically movable conductor (106, 206, 306), which can be brought into an electric circuit between the terminal contacts (3) of the secondary winding,

a safety device (107, 207, 307) for

Blocking access to the inside of the housing terminal contacts (3), which may be in a backup status or release status, the access to the terminal contacts (3) by the security device (107, 207, 307) is blocked in the backup status, so that a connection of a conductor to a terminal contact (3) or a separation of a conductor from a terminal contact (3) is not possible

and the access to the terminal contacts (3) by the safety device (107, 207, 307) is released in the release status and the short-circuit device (105, 205, 305) the connection contacts (3) in the release status

short-circuits, so that a connection of a conductor to a terminal contact (3) or a separation of a conductor from a terminal contact (3) is possible.

2. Current transformer (1) according to claim 1, characterized

characterized in that the safety device

(107,207,307) as a cover sleeve (107) is formed, which in such a way in the housing (2) can be inserted, that they Access to the connection contacts (3) blocked and

simultaneously opens the short circuit device (105).

3. Current transformer (1) according to claim 1, characterized

in that the safety device (107, 207, 307) is designed as a flap mechanism, which has an insulating separating element (209) and flaps (207), by means of which, in the securing status, access to the

Connection contacts (3) is closable, wherein the

Short circuit device (208) through the insulating

Separating element (209) in the fuse state can be interrupted and the flaps (207) and the separating element (209) are mechanically coupled in such a way that the flaps (207) in

Backup status are locked and the

Short circuit device (208) is separated by the separating element (209), and the flaps (207) are opened in the release status and the short-circuiting device (208) short-circuits the terminal contacts (3).

4. Current transformer (1) according to claim 3, characterized

characterized in that the separating element (209) is provided with lateral arms (210) which are movably connected on each side to a flap (207) so that a distal removal of the separating element (209) causes lifting of the flaps (207) ,

5. Current transformer (1) according to claim 3 or 4, characterized

in that a guide mechanism makes it possible for the flaps (207) to slide open when lifted on one side.

6. Current transformer (1) according to one of the preceding claims, characterized in that the short-circuiting device (105, 205) is designed as a circuit breaker, via which the current circuit between the terminal contacts (3) in Backup status of an element of

Safety device (107, 207) in the form of a cover sleeve (107) or a separating element (209) is separable.

7. Current transformer (1) according to one of the preceding claims, characterized in that the short-circuiting device (105, 205) as a mechanically movable conductor (106, 206,

306) has a spring-loaded conductor (106, 206) via which the current circuit between the connection contacts (3) can be closed, the connection contacts (3) each have a short-circuit contact (108, 208) or are electrically conductively connected to such an element the safety device (107, 207) as a cover (107) or as a separating element (209) is formed of insulating material and the cover (107) or the

Separating element (209) between the spring-loaded conductor (106, 206) and the short-circuiting contacts (108, 208) is insertable insulating, so that the electric circuit between the terminal contacts (3) is interrupted.

8. Current transformer (1) according to claim 1, characterized

characterized in that the safety device (107, 207,

307) is designed as a contact cover (307), which can be pushed or closed by moving, which in the backup state closed access to a terminal contact (3) in the backup status

blocked and deferred in the release status

Access to the terminal contact (3) releases, and wherein the short-circuiting device (305) as a mechanically movable conductor (106, 206, 306) has a sliding contact (306) which is coupled to the contact cover (307) such that by moving the contact cover (307) the

Shorting device (305) can be opened or closed.

9. Current transformer (1) according to claim 8, characterized

in that a contact cover (307) of a connection contact (3) can be pushed individually and over each contact cover (307)

Connection contacts (3) of the secondary coil via a respective short-circuit device (305) are kurzschließbar.

10. Current transformer (1) according to claim 8 or 9, characterized in that the contact cover (307) and the sliding contact (306) are rigidly connected together or formed as an element, so that closing the sliding contact (306) sliding the contact cover (307) causes.

11. Current transformer (1) according to claim 8, 9 or 10, characterized in that the sliding contact (306) locking lugs (312), which ensures a safe closing of

Sliding contact (306) and the short-circuit device (305) effect and / or display.