DE963629C - Impedance relay - Google Patents

Description

(WiGBl. P. 175)

ISSUED MAY 9, 1957

Aio583VIIIbl2ic

Impedance relay

(Ges. Of 15.7.1951)

It has already been proposed in a high-speed relay with holding magnets to excite the direct current winding from the mains voltage via a rectifier, while the mains current is used for alternating current magnetization. To eliminate the second harmonic, was henceforth proposed to feed multiple DC coils, for which two should be rectified by 90 ⁰ or three to 6o ° electrically shifted alternating currents.

One in the circuits specified so far The problem that was not completely resolved was the great variability of the rectifier resistance in Dependence on the current load of the rectifier plates. This disadvantage could only get through high series resistances and thus relatively high power consumption of the circuit in bearable Limits are kept.

The variability of the rectifier resistance has significant disadvantages.

The phase currents resulting from the single-phase three-phase transformation are not proportional to the voltage given a variable voltage U ". Hence the resulting changes

7Oi 512/409

DC magnetization AWg in the "voltage winding" of the holding magnet is not proportional to the phase voltage, while the magnetization of the "current winding" (AWj) is proportional to the phase current. This becomes the trip ratio

AWe AWj

kf (U) -U cJ

ίο Therein, k to the constants c and the dependent variable of unwanted U / (U) entered, which makes the set trip impedance with the height of the phase voltage variable. Due to the current dependency of the rectifier resistance, the composition of the phase resistances consisting of reactive and active resistances changes and thus the size and phase of the phase currents. A change in the phase position, however, causes an increase in the waviness of the magnetization and thus a further reduction in the accuracy of the impedance measurement. These disadvantages are eliminated according to the invention in that to eliminate the variable rectifier resistance, current and

the voltage side are designed to be proportionate, in that a line simulation is selected on the current side of a shunt, its terminal voltage is proportional to both the short-circuit current and the voltage on the voltage side is in phase.

The invention is shown in the drawing, for example.

Fig. Ι a shows a largely schematic diagram of the arrangement according to the invention, in which the voltage-side relay winding W _{1 is} fed via a single-phase multi-phase circuit and rectifier G ₁ from the alternating current network; the current-side winding W ₂ is fed via a single-phase multiphase circuit and rectifier G ₂ according to the invention by a voltage u which is proportional to the short-circuit current and which is in phase with the voltage U on the voltage side of the relay; the shunt S, at which this voltage is tapped, is dimensioned so that it is a replica of the line. For the purpose of eliminating the rectifier resistance, the current and voltage side of the arrangement are designed to be proportionate, which will be explained in more detail using the more detailed circuit according to Fig. 1b.

Sets one (Fig. Ib) the Wideretandselemente and rectifiers on current and voltage side of the same size and makes the turns of current and voltage winding equal to each other (% - z _2; W ₁ = W _2), so solves the adhesion magnet at J ₁ = i ₂ off. However, since the rectifier resistances G ₁ = G ₂ for I ₁ = i ₂ , the terminal voltages U and u must also be dimensioned to be the same.

Now is

AWe AWj

c-f {u) -J

= S- J).

In the event of a trip , U = u and AWb _ k_'U_

AWj C 'J "

The response impedance of the impedance element has thus become constant.

In order to eliminate the second harmonic, the direct current windings W ₁ and W ₂ are fed in a known manner either by two rectified alternating currents, which ^{are shifted in their phase position by 90 0} , or by three rectified alternating currents, which are in their phase position by 6o ° are shifted against each other. In the arrangement of Fig. 1 b in each of the two circuits is each a so-called single-phase two-phase circuit used are produced with the aid of suppressing the second harmonic two 90 ⁰ mutually phase-shifted currents. Of course, instead of this circuit, the so-called single-phase three-phase circuit can also be used, which is shown in Fig. 2a of the drawing.

As already mentioned in the introductory description, it is known to use holding magnets a high-speed relay via separate windings from such single-phase multi-phase circuits to excite.

An improvement in the already known circuit is achieved by eliminating the phase separation on the DC side. For this, as Fig. 2a shows, galvanic separation of all phases on the alternating current side is required, which is achieved by intermediate converters A and B. The magnet only has one voltage winding W ₁ . The delaying compensating current in the direct current circuit, which is created by the decay of the DC field in the holding magnet and which can be closed via the rectifier, has a damping resistance in D.

It is also possible to use the two rectifier circuit shown in Fig. 2b instead of the four rectifier circuit (Graetz circuit). For this purpose, the three-phase system has a zero point N ^{in a 120 °} circuit. Both circuits require the same effort for the same output.

The ripple of the direct currents, which increases due to the variable rectifier resistance, is made harmless to a large extent by the shunt S. This shunt represents a simulation of the network impedance, with

which he has the relationship of resistance— ■ in common.

The voltage ii "which is proportional to the short-circuit current" thus always has the same phase position as the short-circuit voltage U ", which is the terminal voltage of the line impedance. A significant phase shift of the harmonics in relation to one another in the primary and secondary direct current of the holding magnet can therefore no longer occur with an approximately correct setting of S in relation to the calibration.

An even more important task of the impedance shunt is to keep the DC link away in the short circuit current from the power side of the relay. This well-known effect explains is as follows: If the short circuit occurs when the voltage crosses zero, the Reactance of the short circuit means the occurrence of a direct current component in the short circuit. The size and course of the direct current determines the

Time constant - = the network impedance. Since the resistor S has the same time constant, its terminal voltage u, like the phase voltage in the short circuit when the direct current element occurs, remains sinusoidal and without a direct voltage component.

Since the relay is now triggered at? 7 "= m_ and m ~ - SJ ^ , the desired trigger impedance can be set by changing S. The easiest way to do this is not to change the resistance S, but to change the tap on w ~ by means of suitable taps.

According to Fig. Ib, there is now no need for a separate winding for the current and voltage side on the holding magnet. For I ₁ = i ₂ , the common winding w is de-energized and the magnet trips. As before, the additional holding current of the holding magnet is supplied by an auxiliary DC voltage and flows through an auxiliary winding of the holding magnet.

The retrieval of the armature from the impedance element and at the same time also the armature of all other holding magnets used in the protective device is carried out, for example, by a small single-phase AC motor with auxiliary phase.This motor, as has already been proposed in a similar way, is switched on by the dropping of some adhesive armature and a crankshaft rotated 360 ^0. Each anchor is connected to a crank in the manner shown and is returned to its rest position when it has switched on the return mechanism by falling off.

If the existing auxiliary direct current is to be used for + S retrieval, it is advisable to to use a lifting or rotary magnet instead of a commutator motor.

Fig. 3 shows such an arrangement. If the anchor A falls on the resilient. Return arm F, it closes the excitation circuit of the lifting magnet H through the contacts 1. This magnet pulls all fallen armatures to the pole face P of the holding magnets. Shortly before reaching the end position E , it opens its own circuit in 2. Since a dry rectifier G is connected in parallel to its winding, which allows the constant field to slowly decay through the equalizing current i _a , the magnet pulls through to the end position.

When falling back, it closes contact 2 again. However, since contact 1 remains open due to armature A remaining on an adhesive surface P , the excitation circuit of the magnet is not switched on again. The contacts 1 of all existing holding magnets are connected in parallel.

Claims (7)

Patent claims: 1. Impedance relay, characterized in that to eliminate the variable equal judge resistance current and voltage side . are carried out proportionally by a line simulation on the current side of a shunt is selected whose terminal voltage is firstly proportional to the short-circuit current and secondly to the voltage on the voltage side is in phase. 2. Impedance relay according to claim 1, characterized in that from the single-phase multi-phase shaping Phase currents arising after suitable galvanic separation on the alternating current side via full-wave rectification are fed to a common DC winding of the holding magnet, 3. Impedance relay according to claim 1 or 2, characterized in that the current winding and voltage winding of the relay are combined to form a common winding. 4. Impedance relay according to claim 1 or the following, characterized in that the DC circuits get damping resistors, go 5. Impedance relay according to claim 1 or the following, characterized in that the The size of the triggering impedance is set by changing the tap, 6. Impedance relay according to claim 1 or the following, characterized in that the Retrieval of the fallen anchor by a direct or alternating current is made by lifting or rotary magnets, which is caused by the falling of an armature be switched on briefly. 7. Impedance relay according to claim 1 or the following, characterized in that the Lifting magnet vocr interrupts its circuit when reaching the end position, but with help a damper winding or a valve parallel to the main winding, which only provides the decay current lets through, briefly retains his excitement and thus reaches the end position, only then to return to the starting position. Considered publications: German patent specifications No. 625 643, 643 824, 667853; VDE-Fachberichte, Vol. 10, 1938, pp. 158 to 168. 1 sheet of drawings © 709 512/409 5.57