SI9800040A - Circuit for symmetric protection of telecommunication systems against intrusive line currents by two thermocoupled ptc elements - Google Patents

Abstract

Subject of the invention is a circuit for symmetric protection of telecommunication systems against intrusive line current by two thermocoupled PTC elements and represents an integral part of the secondary protection of analogue or digital line inputs of telecommunication systems. The circuit for symmetrical protection of telecommunication systems against intrusive line current by two thermocoupled PTC elements features elements (PTCa) and (PTCb) themocoupled via a PTC support (2). Apart from that the switch-off contacts (4, 4') are made in such a way that their overstress-designed switch-off elements are extended to the plug-in part of the circuit according to the invention, thus providing a direct contact with the contact springs of the input module, which is particularly of advantage at high current loads.

Description

SYMMETRIC TELECOMMUNICATION PROBLEMS

SYSTEMS BEFORE ALLOWED LINE FLOW WITH THERMAL

ASSEMBLED PTC ELEMENTS

The subject of the invention is a circuit for symmetrical protection of telecommunication 20 systems against forced line current with thermally coupled PTC elements and is an integral part of secondary protection of analog or digital line inputs of telecommunication systems. The invention belongs to the class H 02 h 3/08 of the international patent classification.

A technical problem that the submitted circuit design successfully solves is such a design of a protective circuit that will allow a low ratio of trip and operating current at the series resistance of the protection module and a short trip time at ambient temperature as determined by the technical requirements for a particular telecommunications system or device.

Protection circuits are known for the current protection of telecommunication devices, which are characterized by operating in each vein independently, and the components of such systems are resistors, PTC resistors and wire fuses. The disadvantage of such protection circuits is the high ratio of disconnect to operating current, they do not guarantee simultaneous disconnection of a and b veins, which can cause additional damage to the protected circuit due to the conversion of symmetric surge to asymmetric impact.

The circuit for symmetrical protection of telecommunication systems against forced line current with thermally coupled PTC elements according to the invention enables the implementation of low current-to-current current protection at relatively low basic resistance of the PTC element such that the PTCa and PTCb elements are thermally coupled via the PTC carrier.

The invention will be explained in more detail on the basis of an embodiment and figures, of which:

FIG. 1 is a schematic view of the assembly and construction of a circuit according to the invention. FIG.

Figures 1 and 2 show a circuit for symmetrical protection of telecommunication systems against forced line current with thermally coupled PTC elements according to the invention.

The input terminals a _and and b _{and the} circuits of the invention are connected to a gas arrester 1, and each via a PTC element on the output terminals a _ou t and b _out . Thus, terminal a _and through the element PTCa are connected to terminal a _ou t, terminal b _and via element PTCb to terminal b _ou t. In order for the circuit to function efficiently according to the invention, both PTC elements PTCa and PTCb must have io very similar basic resistance and good resistance across the entire temperature range. The PTC elements are thermally coupled via the PTC carrier 2, which substantially determines the minimum cut-off current of the PTC assembly. The PTC bracket 2 has a shaped base portion 2a in the form of a circular surface whose dimension corresponds to the dimension of the PTC elements. On the one hand, is the base portion 2a extends into a rectangular striped portion 2b which is inserted into the supporting surface of the circuit of the invention and secured with a solder. The shape of the PTC carrier 2 substantially determines the minimum disconnect current of the entire PTC assembly.

The coupled PTC elements take on the role of secondary protection, while in the case of stronger current surges, which are usually accompanied by an overvoltage surge of more than 200 V, the primary protection is performed by means of a gas arrester 1 and the primary disconnection enabled by the 4.4 'cut-off contacts.

The 4,4 'disconnecting contacts are arranged in such a way that their pre-shaped disconnecting parts are extended into the plug-in part of the circuit according to the invention so that the disconnecting contacts 4,4' are in direct contact with the contact pins of the plug-in module, which is especially advantageous at high current loads. . After disconnecting the disconnecting contacts, the contacts 4,4 'are glazed with the earthing electrode 3.

The primary disconnection occurs when the temperature at the terminals of the gas arrester 1 rises above the melting point of the used solder at the junction between the gas arrester 1 and the disconnect contacts.

4.4 '.

For:

ALFA, doo, Ljubljana Iskra TEL, Kranj

Mirjan PIPAN, inc, patent agents

Claims (4)

PATENT APPLICATIONS 1. A circuit for symmetrical protection of telecommunication systems against forced line current by thermally coupled PTC elements, characterized in that the PTC elements (PTCa, PTCb) are thermally coupled via io PTC carrier (2) or other temperature dependent (NTC, POLY SVVITCH) elements. 2. Circuit for symmetrical protection of telecommunication systems against forced line current with thermally coupled PTC 15 elements according to claim 1, characterized in that the PTC support (2) has a circular shaped base part (2a) whose dimension corresponds to that of the PTC elements, while the base part (2a) is on one side. 20 extends into a rectangular striped portion (2b) that is inserted into the supporting surface of the circuit and secured by a solder. 3. Circuit for symmetrical protection of telecommunication systems against forced line current with thermally coupled PTC elements, 5, characterized in that the disconnecting contacts (4,4 ') are over-shaped and arranged such that their disconnecting parts are extended into the plug-in portion of the circuit of the invention.