DE2331708A1

DE2331708A1 - Overload protection circuit with PTC resistor in series with load - uses sharp step in resistor temperature resistance characteristics

Info

Publication number: DE2331708A1
Application number: DE19732331708
Authority: DE
Inventors: Gerd Rudi Willi Ebinger
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-06-22
Filing date: 1973-06-22
Publication date: 1975-01-16

Abstract

The overload protection circuit consists of a PTC resistor in series with the load. The PTC resistor has a sharp step in its temperature/resistance characteristics so that it acts almost as a cut-out. For higher currents several such PTC resistors may be coupled in parallel with one another and in series with the load. For higher voltages several such PTC resistors may be connected in series. Where several PTC resistors are used, they are mounted on a common base-plate whose load terminals are mutually insulated, thus providing a protective divider.

Description

Erfinder: Gerd Ebinger, 2 Hamburg 61, Teutonenweg 81 Beschreibung : Kurzschlußsicherung von StromkreisenInventor: Gerd Ebinger, 2 Hamburg 61, Teutonenweg 81 Description : Short-circuit protection of electrical circuits

mittels PTC-Widerstände.by means of PTC resistors.

Die Erfindung betrifft die Verwendung von PTC-Widerständen, mit einem scharfen Kennlinienkniek in der Widerstands/ Temperaturkennlinie, als Sicherungselement zur Sicherung von elektrischenrStromkreisen. Von der KlemmeO) fließt ein Strom über den PTC-WiderstandC 1) und die Verbrauchtere 2) zur Klemmeζ4). Beim Anlegen einer Wechselspannung fließt der Strom auch entgegengesetzt.The invention relates to the use of PTC resistors, with a sharp Kennlinienkniek in the resistance / temperature characteristic, as a securing element for securing elektrischenrStromkreisen. A current flows from terminal O) via PTC resistor C 1) and the consumer 2) to terminal 4). When an alternating voltage is applied, the current also flows in the opposite direction.

Werden die Verbrauchet2) kurzgeschlossen, so erwärmt sich der PTC-Widerstand(1) schnell durch den zu großen Kurzschlußstrom und ändert nach dem Erreichen des Kennlinienknickes seinen Widerstand um einige Größenordnungen, Nun wird der PTC-Widerstand durch den Reststrom auf hoher Temperatur gehalten. Nach dem Unterbrechen de» Stromes, zum Beispiel durch Abschalten, hat in wenigen Sekunden der PTC-Widerstand seinen Kaltwiderstand erreicht.If the consumables2) are short-circuited, they heat up the PTC resistor (1) quickly due to the excessive short-circuit current and changes its resistance by a few orders of magnitude after reaching the kink in the characteristic curve. Now the PTC resistance kept at a high temperature by the residual flow. After the current has been interrupted, for example by switching off, the PTC resistor has reached its cold resistance in a few seconds.

Vorteile dieser Anordnung sind, daß der heruntergeregelte Kurzschlußstrom wesentlich kleiner als der zuvor geflossene Betriebstrom ist. Halbleiterkühlkörper und Leiterbahnen brauchen nicht für den Kurzschlußfall dimensioniert zu werden, weil andauernde Kurzschlußströme nicht auftreten können. Da diese Art der Sicherung selbstheilend ist,braucht der PTC-Widerstand nicht zugänglich montiert zu werden und kann wegen der geringen Verlustleistung in gedruckte Schaltungen und Module eingelötet werden.The advantages of this arrangement are that the down-regulated short-circuit current is significantly smaller than the operating current that previously flowed. Semiconductor heat sinks and conductor tracks do not need to be dimensioned for the event of a short circuit, because permanent short circuit currents cannot occur. Since this type of fuse is self-healing, the PTC resistor does not need to be mounted in an accessible manner and can be soldered into printed circuits and modules because of the low power dissipation.

_ P —_ P -

409883/0095409883/0095

Für die Anwendung in Sicherungsverteilem, zum Beispiel in Kraftfahrzeugen, können mehrere PTO-Widerstände-Schichten (6,7,8 und n) auf einer gemeinsamen leitenden Grundplatte(5) aufgebracht werden. Die Anschlüsse(9»1o,11 und m) der PTC-Widerstandschichten(6,7|8 und n) zu den Verbrauchern werden getrennt herausgeführt.For use in fuse distributors, for example in Motor vehicles can have multiple layers of PTO resistors (6,7,8 and n) are applied to a common conductive base plate (5). The connections (9 »1o, 11 and m) of the PTC resistance layers (6,7 | 8 and n) to the consumers led out separately.

In einem elektronischen Spielzeuggerät wurde ein PTC-SA PTC-S Wideretand der Pa. Valvo mit dem Typ 8222 298 71521Resisted the Pa. Valvo with the type 8222 298 71521

yerwendet.used.

Kaltwiderstand: 1,6 Ohm Cold resistance: 1.6 ohms

Spannungsabfall Maximal 15 Volt Voltage drop 15 volts maximum

Verlustleistung maximal 400 mW Power loss maximum 400 mW

Betriebst roe ohne zusätzliche Kühlung bis 400 mA. Operating roe without additional cooling up to 400 mA.

Patent claims:

409883/0095409883/0095

Claims

Patent claims:

Claims / i.) Circuit arrangement for protecting circuits, in which, in the event of a short circuit, the short circuit current is reduced to a low residual current without the PTC resistor being destroyed as a fuse, characterized in that a PTC resistor (1), the one has a sharp bend in the temperature / resistance characteristic, is connected in series with the consumers (2) to be protected, and which, in the event of a short circuit, heats up due to the short-circuit current and then increases its intrinsic resistance by several orders of magnitude.

Claim 2. Circuit arrangement according to claim 1, characterized in that the PTG resistord) to increase the current through the consumer (2) consists of several PTC resistors.

Claim 5 » Circuit arrangement according to Claim 1, characterized in that the PTC resistor (i) consists of several PTC resistors connected in series to increase the voltage range.

Claim 4 ·. Circuit arrangement according to Claim 1, characterized in that several PTC resistors (6, 7, 8 and n) are applied to a common lead fiswstg base plate (5) whose connections (9 »10, 11 and m) to the consumers are isolated from one another so that a fuse distributor is created.

409883/0095

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