DE581352C - Protective device for multi-phase AC machines, especially single armature converters - Google Patents

Description

GERMAN EMPIRE

ISSUED ON JULY 26, 1933

REICH PATENT OFFICE

PATENT LETTERING

CLASS 21 c GROUP 68so

Sy / 2p / VIIIb \ 2ic Date of publication of the patent grant: July 6th

Patented in the German Empire on December 3, 1926

Multi-phase single armature converters, for example those that convert three-phase current are determined in direct current, it is known that protection is provided both on the three-phase current side as well as on the direct current side by automatically acting switches against overcurrent and short circuit. There are many things for this Facilities have been specified that will not be discussed in more detail here. the However, previous protective devices all suffer from the defect that they are between single-phase or asymmetrical multiphase and symmetrical multiphase short-circuit make no significant difference. So far, only in those cases in which asymmetrical disturbances are present, but the current intensity does not reach the response value of the protective device, additional Switching devices provided that a

ao prevent prolonged work with significant asymmetrical loads. so but it is a single-phase short circuit ζ. Β. for the commutation of the DC side of the One armature converter is particularly dangerous because of the double Speed against the rotating field rotating around the room. This induces namely in the commutating coils additional alternating voltages, which cause strong sparking of the brushes and the grinding surface the brushes and the commutator can attack. Under particularly unfavorable circumstances this spark formation can also give rise to round fires. It was missing so far a device that responds to asymmetrical overloads more quickly than to normal, overloads symmetrically distributed over all three phases. This deficiency is remedied by the subject matter of the invention, namely in that separately excitable relays in an overcurrent switch controlling auxiliary skreis of individual phases are arranged so that the overcurrent switch only when responding to one or one Relay responds immediately, while if all relays respond at the same time, a delayed response Control element of the overcurrent switch is activated.

The invention thus offers the new possibility of using the direct current circuit of a single armature converter to protect extensively against the adverse effects of asymmetrical interference in the three-phase network without the Overcurrent switch on each maybe only temporary and therefore responds to harmless symmetrical overload.

In Fig. Ι the drawing is an embodiment of the subject matter of the invention shown schematically, the one to the shooter of a three-phase single armature converter illustrates certain apparatus. 1, 2, 3 each designate a magnet winding of

*,) The patent seeker stated as the inventor:

Dipl.-Ing. Ernst Kloss in Falkensee b. Berlin-Spandau,

Claims (3)

Switching relays that are connected to the secondary windings of voltage converters that are connected on the primary side, for example, between two supply lines of the three-phase current feeding the converter. Switching bridges 4, 5, 6 are connected to the magnetic core of these switching relays, which in the manner shown in FIG if the current in the coils i, 2, 3 is correspondingly low , bridge a pair of contacts 13, 14, 15, 16 and 17, 18 each. A circuit fed from the collector battery 19 to the contacts 7, 9, 11 on the one hand and 13, 15, 17 on the other hand contains the magnet winding 20 of an instantaneous trip relay 21, which triggers the overcurrent switch (not shown) when it is triggered. The contacts 8, 10, 12, 14, 16, 18 are connected to one another by a line 22. At points 23 and 24 of the supply lines to the contacts (FIG. 1), a delayed trip relay 26 (FIG. 2) equipped with a coil 25 is also assigned, through which the overcurrent switch can also be triggered. If the three-phase network is fault-free, all three magnet windings 1, 2, 3 are uniform energized and there are therefore the associated switching bridges 4, 5, 6 in the one shown in FIG raised position. In this case, it is fed by the collector battery 19 Auxiliary circuit interrupted at contacts 13 to 18. However, it occurs in the three-phase network an asymmetrical disturbance, which results in a drop in the voltage in coil 1 has, the bridge 4 falls, while the bridges 5 and 6 remain raised. It flows then a current from battery 19 through 9, 5, 10, 14, 4, 13, 20 back to 19. The trip relay As a result, 21 responds and the overcurrent switch trips. Basically the same occurs when z. B. the current of the coil 2 or the coil 3 decreases and consequently the switching bridge 5 or 6 falls, while the switching bridge 4 in the raised Position remains. Even if two of the three bridges ^, 5, 6 fall down at the same time, results in the same effect. The coil 25 of the trip relay 26 is short-circuited here, thus out of action as long as one of the three bridges 4, 5, 6 is in the upper position occupies. So only when three bridges fall does it receive power and respond. the slower tripping is achieved by the movement of the switching bridge of the Trip relay 26 z. B. is slowed down by the escapement 27 indicated in FIG. The resistance of the coil 25 is such that when the three fall at the same time Bridging the current in the coil 20 is not sufficient, the trigger relay 21 to respond bring to. According to a simplified embodiment, you can without the trip relay 26 with the help the coil 20 intended for rapid tripping in the event of an asymmetrical fault (Fig. 1) also cause the slowed release in the case of symmetrical disturbances. One can too for this purpose z. B. controlled by the coil 20 instantaneous trip relay 21 as Form a current-dependent delayed trip relay, d. H. as a relay, which with small Relay current triggers slower than with a larger one. Instead of the relay coil 25, As indicated in Fig. 1 with dashed lines, an ordinary resistor is connected: when the three bridges 4, S, 6 drop, the coil current is smaller than when only one or two bridges drop, whereby with an appropriate design of the relay 21 this later the control circuit of the overcurrent switch closes. Of course, the magnet windings i, 2, 3 of the switching relays can also be connected to the three-phase network connect that they do not respond to voltage, but to current changes. The effect of the arrangement remains essentially unchanged. The invention is not only important for protecting multi-phase single armature converters, but is generally suitable for all multi-phase AC machines, regardless of whether they are used as electricity generators or be operated as a motor, because even with such machines, this has due to asymmetrical Mains disturbances caused undesirable side effects, rotating fields rotating at twice the speed against the room result. It can e.g. B. induces additional currents in the damper winding usually present in synchronous machines that cause an inadmissible heating of this winding. Such disturbances can, however, with the described Easily prevent the establishment, as it provides a means at hand, the overcurrent switch set so that it works much faster in the event of asymmetrical overload than with symmetrical overload, exactly as it corresponds to the needs of the practice. Paient claims: i. Protective device for multi-phase AC machines, in particular single armature converters, against asymmetrical and excessive symmetrical loads, characterized in that of individual Phase separately excitable switching relays in an overcurrent switch controlling auxiliary circuit are arranged so that the overcurrent switch only when Response of one or individual switching relays responds immediately, while with simultaneous response of all switching relays a delayed control element (21 or 26) of the over current switch in Activity is set. 2. Protection device according to claim 1, characterized in that individual Switching relays of the switching device are designed as switching relays with two pairs of contacts each and that of the switched-on position assigned contact pairs (7, 8; 9, 10; 11, 12) one contact each (7, 9, 11) to one pole of a direct current source (19) and of the switch-off position assigned contact pairs (13, 14; is, 16, 17, 18) one contact each (13, 15, 17) via the magnet winding (20) a current-dependent on the strength of the auxiliary current delayed trip relay (21), which is used to weaken the excitation Resistance is connected upstream, connected to the other pole of the direct current source (19) is, while the other contacts (8, 10, 12, 14, 16, 18) are all with- ' are conductively connected to each other. 3. Protection device according to claim 1, characterized in that the magnet winding (20) an instantaneous trip relay (21) a delayed trip relay (26) is connected upstream, the resistance value of which is such that when all of them respond at the same time Contactors the magnet winding (20) of the undelayed release relay (21) The current flowing through is not sufficient for the trip relay (21) to respond bring. 1 sheet of drawings