DE595077C - Circuit arrangement for thermal relays in a daisy chain, especially in telecommunications systems - Google Patents

Description

The invention relates to a circuit arrangement for thermal relays in telecommunications systems, which work to bridge faults in a chain connection, with the connection after a thermal relay has responded additional thermal relays are connected in parallel.

There are known arrangements for this in which the winding of each relay a resistor is connected so that 'for the duration during which the relay is energized stands, the current is essentially constant; that which can be determined by this resistance Amperage depends on the desired response time. In practice, current intensities are often required for the relay windings not withstand as long-term stress. The invention avoids despite simultaneous Increase the speed of work this drawback by the fact that the circuit to each of the thermal relays via a common series resistor and comes into effect in such a way that a response time for the thermal relay that responds first shortening, stronger response current tind after a or several thermal relays, a weaker holding current that avoids overload is established comes.

In the accompanying drawing, the invention is shown in an exemplary embodiment, namely a small self-access system with a total of three connection paths and three call seekers is selected as an embodiment. The call seekers work in a known way in a chain circuit, with the provision of a further one by an organ of the occupied call seeker (contact as ¹ , as ² , as ^s ) or, in the event of malfunctions, the passing on of the stimulus by one assigned to the disturbed call seeker after a call seeker has been assigned Thermal relay Th ¹ , Th ² , Th ^B takes place. It is also indicated in the drawing that the known shut-off relay G is guided via contacts of the call seeker organs. If all three outputs are occupied, the falling G relay prevents an unsuccessful attempt at occupation and transmits a busy signal. Of the relay An, which is responsible for starting the call and signaling machine and possibly switching on a charging device, only the second is. Winding On "is shown. The processes take place as follows:

The subscriber Tn lifts off its receiver, the stages relay T in the circuit is: earth, battery, contact g ^'2, winding I of the relay T, contact t _n ^2, subscriber loop contact tu ^1, excited earth and operates its first contact stage. By closing the con tact ti ¹ , the incentive to call seeker AS ^{1 is} given on the one hand via earth contacts ti ¹ , tu ³ and th ¹ and on the other hand the circuit: earth, contacts / ¹ , tifi, thermal relay Th ¹ , contact g · ¹ , Resistance Wi, battery, earth closed. If the call finder is in order, then in a known manner after checking via contact tr and disconnect

of the contacts tu ¹ , tu ² and tifi via the contact as ^{1 of} an organ of the call seeker, AS ^1, the chain to the next call seeker AS ^{2 is} closed. In the event of a fault in the call seeker ^ 4S ^1, however, the thermal relay Th ¹ remains connected via contact tjfi, so that it has time to activate its contact th ¹ and switch through the chain to the call seeker ^ 4S ² in place of contact as ^1.

The thermal relay 77z ^{2 is connected in} parallel to the thermal relay Th ¹ , which greatly reduces the holding current for Th ¹ and protects the winding from burning out. The same applies to the call seeker ^ 4S ³ : If the call seeker AS ¹ is OK, the chain is connected through contact as' ² and the stimulus and the thermal relay are switched off through contact tu ³ after checking; if, on the other hand, it is not in order, the call seeker AS ^{3 is} stimulated via contact th ² and the thermal relay Th ^{3 is switched in} parallel to Th ¹ and Th- , whereby the holding current of these relays decreases further.

By dimensioning the series resistance W / can also be used for the relays that work after the relay switched on first and (a lower response current get a greater working speed than this with circuits with each Thermal relay individually assigned series resistors is possible. This is because that by shortening the response time, the time of continuous load is also reduced is, because the accelerated passing on of the incentive disconnects the already switched on Thermal relays or the parallel connection of further thermal relays also accelerated will.

If the last call seeker is occupied, the relay G _{1 is switched off} if all call seekers are OK. The relay Q then places its contacts g ¹ and g ² in the strongly extended position; as long as any contact ti ^{1 is} closed, then the starting relay All comes into operation via its winding An ¹¹ , the high resistance of which excludes the effectiveness of the thermal relay. A busy signal is sent to the transmitter Ue via contact to (activation of the call and signal machine), which is now connected to the calling subscriber via contact g ~.

Claims (4)

Patent claims: 1. Circuit arrangement for thermal relays in a chain connection, which are used for bridging disturbed organs, especially in telecommunications systems, serve, after If a thermal relay is triggered, additional thermal relays are connected in parallel takes place, characterized in that the circuit to each of the thermal relays via a common Ballast resistor is performed and so comes into effect that for the first responsive thermal relays have a stronger response current that shortens its response time and after one or more thermal relays have been switched on, a weaker one, the overload avoiding holding current comes about. 2. Circuit arrangement according to claim i, characterized by such a dimensioning of the ballast resistor that when all thermal relays are connected in parallel, the relay switched on last receives a response current which is equal to its permissible continuous current. 3. Circuit arrangement according to claim τ, especially for call seekers in small self-connecting systems, characterized in that the thermal relays are switched off in a manner known per se (z. B. by a contact of the switch-off relay G) over the common part of the circuits when no call seeker more is operational. 4. Circuit arrangement according to claim 1 and 3, characterized in that when Occurrence of the disconnection of the common circuit from the series resistor to a starting relay or a special one Winding of the same is switched, thereby only as long as a call during the shutdown is present, the signal machine to generate a signal for the caller is actuated. For this purpose I sheet drawings