DE1051332B - Overvoltage protection device for subscriber devices on telecommunication lines affected by high currents - Google Patents

Description

Telecommunication overhead lines are at risk from lightning strikes and often in the vicinity of high-voltage lines, for example, directly on the high-voltage linkage, laid so that these high-voltage lines induced more or less large interference voltages on the telecommunication lines can be. In order to keep these interference voltages away from the subscriber devices, it is known the telecommunication lines to the subscriber by means of transformers, chokes od to be provided with a center point earthing at the same time. In this earth connection one can put an electromagnetic Switch on relays with earthing contacts and thus an already effective overvoltage protection reach. Other known protective circuits provide that occurring with thermally triggered switching elements To derive interference voltages.

If a commercially available relay is used as a protective device, it can happen that with Interference that occurs briefly and whose amplitude changes, the relay flutters, so that the protection of the connected subscriber devices cannot be guaranteed with certainty. Also must When using a relay, make sure that the response time has a certain fixed value, which cannot be undercut. This is the case with extremely short overvoltages such as lightning strikes can occur, it is possible that there will be no lockout.

Compared to this prior art, the invention brings a significant improvement in that the relay equipped with grounding contacts is designed as a mechanically lockable backup relay, the grounding contacts of which are adjusted so precisely that they can serve as spark gaps to protect against overvoltages. This solution has the advantage that the cost of switching elements is extremely low and a maximum of security is achieved for the connected subscriber devices. By using a back-up relay, the contacts of which are locked in the tightening position, an absolutely reliable discharge of interference voltages is ensured after the relay has responded for the first time. The addressed relay can also serve to indicate that interference of a corresponding magnitude has occurred. By the fact that the ground contacts as spark gaps are effective, it is ensured that both very briefly occurring interference voltages and smaller surges that otherwise can not be detected by the relay, are derived via the radio link to Earth.

In the circuit example shown in the drawing, L ₁ and L _{2 are} the two branches of the, for example, on the linkage of a high-voltage

Overvoltage protection device
for subscriber devices on overhead communication lines affected by high currents

Applicant:
Siemens & Halske Aktiengesellschaft,
Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Dipl.-Ing. Paul Simon, Munich,
has been named as the inventor

Line laid telecommunication line, which are sealed off by the transformer Ü against the branches a and b of the local voice line containing the subscriber devices. The primary winding of the transformer is grounded in the middle via line E. In this the winding of the overcurrent relay R is switched on, the contacts ₁ and r ₂ of which are closed when the relay responds, so that they ground _{the lines L 1} and L ₂ before the transformer and relay R. The relay is a so-called backup relay, the contacts ₁ and r _{2 of which are} in the pick-up point

mechanically
through the under
To

be locked, for example cams M ₁ with spring force, so the line

and Ti _i

gen L ₁ and L _{2 can} be unlocked again by hand.

The relay contacts T ₁ and r ₂ are designed as spark gaps in that the distances between the switching arms and the mating contacts are adjusted so precisely that even smaller overvoltages from the lines L ₁ and L ₂ are diverted to the grounding conductor E via these spark gaps. Very strong overvoltages and currents then cause the relay R to respond and thus cause the two long-distance lines L ₁ and L ₂ to short-circuit with the grounding conductor E.

the disorder

809 767/370

Claims (1)

Claim: Overvoltage protection device for Teiliiehmergeräte on high-current-influenced telecommunication lines, which have an electromagnetic relay with grounding contacts containing an electromagnetic relay with grounding contacts via the center point of inductances in front of the subscriber devices, characterized in that the relay equipped with grounding contacts is designed as a mechanically lockable support relay (R) Earthing contacts (r _v r ₂ ) are adjusted so precisely that they serve as spark gaps to protect against overvoltages. Considered publications: German patent specification No. 533 668. French patent addendum No. 38401 to French patent No. 612,470; Journal: "Bell Laboratories Record", 1956, Issue 8, p. 300, Fig. 5. 1 sheet of drawings . © 809 767/370 2.59