DK148028B - ELECTRONIC TRANSMISSION SYSTEM - Google Patents

Description

i 148028 o

The invention relates to an electronic triggering system, in particular for fault current protection relays, as further specified in the preamble of claim 1.

The purpose of trigger devices in electrical protection relays is in some cases to cause a circuit break. Fault current relays respond, as is well known, when the sum transformer of the fault current protection relay is, in the case of fault current, being magnetized by a differential current which affects a relay to a relay lock, the contact of which will then open that particular circuit. In the simplest case, the sum transformer over its secondary winding is connected directly to the trigger. However, in the case of small fault currents, the energy supplied by the transformer is in most cases insufficient, so further measures are required, such as 15 increasing the sensitivity of the triggers. In the end, such triggers are again very sensitive to interference.

To increase the response sensitivity of a trigger device, one must first increase the required trigger energy. This can be done by increasing or improving the magnetic material of the transformer, so that the energy delivered by the small fault currents to the trigger is increased. But here the boundaries are already reached through the structure of the contacts, as well as through the physical parameters of the materials. On the other hand, there are also systems in which the small energy supplied by the transformer controls an amplifier or amplifier relay, whereby - depending on a foreign energy source (mains voltage) - the necessary energy can be supplied to the trigger can be activated.

More conveniently, therefore, is the method that, within a specified period of time, the energy supplied by the transformer is first stored on a capacitor. A trigger device for electrical protection relays, preferably for fault current, voltage voltage or station protection relays utilizing this energy storage principle, is already known from DE-AS 10 57 683. As a voltage dependent switching means a cold cathode relay or a light bulb is used. Admittedly, the known triggers need very high, but only

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148028 2 very short pulses. However, voltage-dependent coupling means of the kind previously described have a very low efficiency for this purpose. Thus, e.g. by a flashlight a voltage of 61 volts to maintain the required voltage of 1 volt.

A device for protection against electrical fault currents which uses a threshold diode as a voltage-dependent switching device is already known from DE-OS 17 88 159. However, since such a threshold diode requires a similar high control voltage as the mentioned lamps, it has been proposed that keep the required control voltage sufficiently large by means of a further winding on the sum current transformer or using a mains voltage present at one of the transformer's primary windings. Admittedly, the secondary-voltage of the transformer must thereby be kept high.

An electronic triggering system of the kind referred to in the preamble of claim 1 is known from DE-OS No. 22 16 001. In this triggering system it is a short-circuit grounding device which is of the energy-independent type which is set in function of a nuclear transformer or toroid. The ground short circuit comprises a rectifier circuit including a normal dual diode rectifier and a single diode rectifier. However, the voltage gain circuit is a circuit 25 which is limited to a simple voltage doubling. This simply adds the voltage of one capacitor to the voltage of another capacitor. These capacitors interact in a particular way and are largely dependent on the charging voltage. In this connection, it is important to prevent the first capacitor from being charged to a voltage higher than that to which the circuit is intended. When such a situation occurs, the trigger and relay circuit built up by two transistors can be put into operation before the second capacitor has reached the desired voltage. This must be taken into account that the diodes for charging the two capacitors are very carefully dimensioned.

148028 3

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As far as the ipulse encoder of this earth-short circuit is, it consists of a two-stage switch to which two transistors are used in a rocker arrangement. Furthermore, the circuit of the ground short circuit device interacts with a transformer whose secondary winding has a center outlet which is directly connected to the capacitor and the trigger coil. The essence of the circuit in the grounding circuitry consists in the generation of two different voltages which serve to charge the two capacitors as well as the dependence of the diodes responsible for charging the capacitors, taking into account the limitations imposed by the capacitors. already referred to. The switch is again a voltage dependent switching device which consists of two components.

The invention has for its object to further develop a release system of the kind specified in the preamble, wherein a capacitor is used for energy storage to produce a short but strong trigger pulse which is instantaneously transmitted to the coil winding of the trigger, the mechanical structure of the trigger being adapted to this trigger pulse. In this way, the contact used for the purpose must be able to disconnect already at very small secondary voltages on the transformer.

The stated object is achieved according to the invention by means of an electronic triggering system of the type stated in the preamble, which is peculiar to the design according to the characterizing part of claim 1.

The advantages of the invention consist in the fact that the electronic trigger system consists of only a few components 30 and circuit elements, which can be arranged in a particularly space-saving and contrived manner. The response of the circuit breaker at very small secondary voltages to the transformer results in a very good efficiency and makes it possible to trigger so that a reliable response threshold is obtained.

Due to the good efficiency of this triggering system, the energy delivered by the transformer can be much smaller by the above system, which means that the

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The volume of the system is reduced or that the fault current required for the interruption can be reduced, both of which favor an improved application and higher protection against electrical accidents. In addition, an auxiliary energy source is not required for operation.

The rectifier circuit used for storing the alternating current supplied by the transformer is designed so that the capacitor discharges at each current half-wave. This means that, based on such a principle, an electronic trigger system, when built into a fault current protection relay, enables the circuit breaker to respond not only to pure alternating current, but also to half-wave current, alternating current DC or strong DC pulses. of arbitrary current direction.

It is also useful to insert a temperature compensation diode in series with the voltage divider, j fr. claim 2.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is illustrated in the following, with reference to FIG. 1 shows the circuit for an electronically triggering system; FIG. 2 is a front view of an integrated circuit unit trigger; and FIG. 3 shows the same as FIG. 2, but seen from 25 above.

As shown in FIG. 1 is a single-phase grid with its phase conductor R and zero conductor N connected to the primary windings 1 and 2 of a sum transformer. A secondary winding 3 connects to a circuit combination consisting of rectifiers 4, 5, 6 and 7 as well as capacitors 8, 9 and 10. In the event of a fault current, an alternating voltage is generated in the secondary winding 3 which is rectified and amplified in the circuit combination. The rising energy is stored in a capacitor 11 within a certain time. An impulse semiconductor 12, 35, which is constituted by a programmable unijunction transistor, has the task, in connection with one of resistors 13 and 14 0 5 140028, to produce the necessary trigger pulse. Hereby a diode 15 for temperature compensation in series with the voltage divider may be inserted. The cathode of the pulse semiconductor is connected to a control electrode in a controllable semiconductor 16. As a controllable semiconductor, e.g. a thyristor is used. As soon as the controllable semiconductor is switched on, the energy stored in the capacitor 11 is suddenly transmitted as a strong trigger pulse on the coil winding of the trigger 17, thereby activating the trigger. The activation of the trigger through a coupling lock and additional coupling means causes the endangered system to be disconnected from the network.

The complete electronic release system consists of as shown in FIG. 2 and 3 are essentially a magnetic circuit 15 consisting of a yoke 18 with the legs 19 and 20 and an anchor 21, a coil winding 22 disposed about the leg 19, a permanent magnet 23 on the winding-free portion of the yoke 18, and a mounting plate 24 on which the building elements for the electronic switch are placed. The entire electronic system is enclosed in a common housing 25.

Claims (2)

148028 O. An electronic triggering system, especially for fault current circuit breakers, with a current transformer that captures a disturbance size, the secondary winding of the current transformer feeds a combined rectifier and voltage gain circuit connected to a back-up energy storage device with a charge capacitor (11) a pulse generator (12) controlled over a voltage divider (13,14) which, after sufficient charging of the charging capacitor (11), controls a voltage-dependent coupling means (16) connected in series with a coil winding in a trigger (17) in the trigger system. discharge the charging capacitor (11) through the coil winding, characterized in that: (a) the rectifier and voltage gain circuit consists of a series connection of at least three diodes (4, 5, 6) interconnected in the system's plus line with the same throughput and one diode (7). ) inserted in the blocking direction between the anode of the first diode (4) and the negative line of the system, that in parallel with 20 the first two diodes (4, 5) are connected to a capacitor (8), the connecting point between the first two diodes (4, 5) being connected to the negative line over a second capacitor (9), a third capacitor (10) being connected in the negative line between the connections of the diode (7) inserted in the blocking direction and the second capacitor (9) and the cathode of the third diode (6) respectively. the connection point between the anode of the diode (7) inserted in the blocking direction and the third capacitor (10) is connected to the one or the charge capacitor 11 respectively. B) the voltage divider (13, 14) is connected in parallel to the charging capacitor (11), the center of the voltage divider being connected to the control electrode on a pulse encoder used transistor (12) whose anode 35 is connected to the system's plus conduit, and whose cathode is connected to the control electrode on a voltage-dependent coupling means designed as a controllable semiconductor (16).