Current transformer having an automatic short-circuit device

1. A current transformer, comprising connection contacts for contacting a secondary winding of the current transformer, which connection contacts can be reached through a housing opening of the housing surrounding the current transformer, wherein the current transformer has a short-circuit device for shorting the connection contacts and the short-circuit device has a mechanically movable conductor that can be brought into a circuit between the connection contacts of the secondary winding,

the current transformer having a safety device for blocking the access to the connection contacts lying inside the housing, which safety device can be in a securing status or release status, wherein the access to the connection contacts is blocked by the safety device in the securing status, such that the connection of a conductor to a connection contact or the disconnection of a conductor from a connection contact is not possible and the access to the connection contacts is released by the safety device in the release status and the short-circuit device shorts the connection contacts in the release status, such that the connection of a conductor to a connection contact or a disconnection of a conductor from a connection contact is possible.

2. The current transformer according to claim 1 , characterised in that the safety device is formed as a cover sleeve which can be inserted into the housing in such a way that it blocks the access to the connection contacts and at the same time opens the short-circuit device.

3. The current transformer according to claim 1 , characterised in that the safety device is formed as a flap mechanism that has an insulating separation element and flaps by which the access to the connection contacts can be closed in the securing status, wherein the short-circuit device can be interrupted by the insulating separation element in the securing status and the flaps and the separation element are mechanically coupled in such a way that the flaps are closed in the securing status and the short-circuit device is disconnected by the separation element and the flaps are open in the release status and the short-circuit device shorts the connection contacts.

4. The current transformer according to claim 3 , characterised in that the separation element is provided with lateral arms that are movably connected on either side to a flap, such that a distal removal of the separation element causes a lifting of the flaps.

5. The current transformer according to claim 3 , characterised in that a guide mechanism enables the flaps to slide thereon when raised from one side.

6. The current transformer according to claim 1 , characterised in that the short-circuit device is formed as a disconnecting switch, via which the circuit between the connection contacts can be disconnected by an element of the safety device in the form of a cover sleeve or a separation element in the securing status.

7. The current transformer according to claim 1 , characterised in that the short-circuit device has a sprung conductor as mechanically movable conductor via which the circuit between the connection contacts can be closed, each of the connection contacts has a short-circuit contact or is electrically conductively connected to such a contact, an element of the safety device is formed as a cover sleeve or as a separation element formed of insulating material, and the cover sleeve or the separation element can be inserted between the sprung conductor and the short-circuit contacts in an insulating manner, such that the circuit between the connection contacts is interrupted.

8. The current transformer according to claim 1 , characterised in that the safety device is formed as a contact cover that can be slid on or closed by displacement and that, closed in the securing status, blocks the access to a connection contact in the securing status and that, slid on in the release status, releases the access to the connection contact, and wherein the short-circuit device, which has a sliding contact as mechanically movable conductor, is coupled to the contact cover in such a way that the short-circuit device can be opened or closed by displacement of the contact cover.

9. The current transformer according to claim 8 , characterised in that a contact cover of a connection contact can be slid on individually and the connection contacts of the secondary coil can be shorted via each individual contact cover via a respective short-circuit device.

10. The current transformer according to claim 8 , characterised in that the contact cover and the sliding contact are rigidly interconnected or are formed as one element, such that a closure of the sliding contact causes the contact cover to be slid on.

11. The current transformer according to claim 8 , characterised in that the sliding contact has detent lugs that cause and/or indicate a secure closure of the sliding contact and of the short-circuit device.

12. The current transformer according to claim 4 , characterised in that a guide mechanism enables the flaps to slide thereon when raised from one side.

13. The current transformer according to claim 2 , characterised in that the short-circuit device is formed as a disconnecting switch, via which the circuit between the connection contacts can be disconnected by an element of the safety device in the form of a cover sleeve or a separation element in the securing status.

14. The current transformer according to claim 3 , characterised in that the short-circuit device is formed as a disconnecting switch, via which the circuit between the connection contacts can be disconnected by an element of the safety device in the form of a cover sleeve or a separation element in the securing status.

15. The current transformer according to claim 4 , characterised in that the short-circuit device is formed as a disconnecting switch, via which the circuit between the connection contacts can be disconnected by an element of the safety device in the form of a cover sleeve or a separation element in the securing status.

16. The current transformer according to claim 2 , characterised in that the short-circuit device has a sprung conductor as mechanically movable conductor via which the circuit between the connection contacts can be closed, each of the connection contacts has a short-circuit contact or is electrically conductively connected to such a contact, an element of the safety device is formed as a cover sleeve or as a separation element formed of insulating material, and the cover sleeve or the separation element can be inserted between the sprung conductor and the short-circuit contacts in an insulating manner, such that the circuit between the connection contacts is interrupted.

17. The current transformer according to claim 3 , characterised in that the short-circuit device has a sprung conductor as mechanically movable conductor via which the circuit between the connection contacts can be closed, each of the connection contacts has a short-circuit contact or is electrically conductively connected to such a contact, an element of the safety device is formed as a cover sleeve or as a separation element formed of insulating material, and the cover sleeve or the separation element can be inserted between the sprung conductor and the short-circuit contacts in an insulating manner, such that the circuit between the connection contacts is interrupted.

18. The current transformer according to claim 9 , characterised in that the contact cover and the sliding contact are rigidly interconnected or are formed as one element, such that a closure of the sliding contact causes the contact cover to be slid on.

19. The current transformer according to claim 9 , characterised in that the sliding contact has detent lugs that cause and/or indicate a secure closure of the sliding contact and of the short-circuit device.

20. The current transformer according to claim 10 , characterised in that the sliding contact has detent lugs that cause and/or indicate a secure closure of the sliding contact and of the short-circuit device.