DE1905505B2 - FAULT CIRCUIT BREAKER - Google Patents

Description

The invention relates to a residual current circuit breaker with a summation current transformer, the primary windings of which are connected to the phase lines of an alternating current system, the release winding of which is connected to a release and the iron core of which is provided with a pre-magnetizing auxiliary winding fed from an auxiliary source, which release provides a first indication, if a fault current is superimposed on the bias current in the summation current transformer due to a ground fault in the AC system.
Conventional residual current circuit breakers, in which the primary winding of the summation current transformer is formed by the conductors to be monitored, and whose secondary winding is connected to the release as a release winding, only react correctly to a pure alternating current residual current. In the case of DC residual currents or mixed residual currents, the DC component does not trip the release. In addition, the direct current component can completely or partially saturate the core of the summation current transformer and cause a shift in the operating point, so that the transformation of the alternating current component is reduced and the release no longer triggers even with an alternating current fault current. Since it is common today to connect direct current consumers to an alternating current network via rectifiers, such direct current fault currents or mixed currents can occur.

A residual current relay is known (Danish patent specification 91184), which according to the difl'erenzsich-

principle works and is especially suitable for alternating current, but which is also used for direct current can be. This relay is based on the application of an electromagnet that works with a permanent magnet is polarized; therefore the relay will only be correct with DC current in one direction react.

It is also known to increase sensitivity a power amplifier between the secondary winding of the summation current transformer and the release to switch using a cathode tube or transistor. To the Supply of the amplifier is used, for example, from the network to be protected via a Rectifier drawn direct current. This pulsating direct current is passed through an auxiliary winding of the summation current transformer, which also serves to connect your input of the amplifier via the Secondary winding to provide a bias voltage (German Auslegeschrift 1 146 181). This switch principle however, it is not suitable for the detection of DC residual currents.

Furthermore, the measurement of direct currents by changing the magnetization in alternating current is possible Inductivities known (see Zeitschrift Elektrotechnik und Maschinenbau, 1959, year 76, p. 579).

The invention is based on the object e ^; To create a residual current circuit breaker that triggers both when an alternating current residual current occurs and when AC fault currents and DC residual currents occur at the same time, and also when a DC residual current occurs.

According to the invention, this object is achieved in a residual current circuit breaker of the type mentioned at the beginning Art solved in that for the additional detection of the earth fault current with direct current consumers, which are fed via rectifiers from an alternating current network, the primary winding of the summation current transformer in the AC supply lines to the rectifier are that to the auxiliary winding a rich AC voltage source is connected, and that the trigger winding of the The summation current transformer connected trip unit is dimensioned, d ^ ß he provides a second display, if in the summation current transformer due to a ground bus in the direct current consumer there is Sets the DC magnetization overlapping the premagnetization.

Another proposal of the invention consists in the advantageous use of this residual current circuit breaker on a pure direct current network, the conductor of which is the primary winding of the summation current transformer forms. In this application, the auxiliary winding of course remains on the named one AC voltage source connected. The trigger provides an indication that the core of the Summation current transformer only one more existing alternating current magnetization Magnetization is obtained by the DC residual current, which increases the current flow to the Causes triggering element, which then delivers the said second display.

Does a change occur? : oil fault current on, so add up the alternating base voltage induced by the auxiliary winding and that generated by the fault current Voltage at the release so that it responds due to the change in the basic voltage.

If a DC fault current also flows in the AC network, this causes a premagnetization and thus a change in the operating point at the core of the summation current transformer. This results in a reduction in the alternating basic voltage on Trigger so that it responds. If you use de & residual current circuit breakers in a direct current network and if there is no fault current, then due to the alternating current in the auxiliary winding

voltage on the shutter release. As soon as a DC fault current flows, the working point at the core is changed, and thus the Alternating basic voltage at the release, so that due to this voltage reduction the release also appeals.

The two windings, the release winding and auxiliary winding, can be separate and with one Primary winding and a .. secondary winding of a transformer are effective. However, the The release winding and the auxiliary winding form a common winding.

The principle according to the invention can also be implemented with a reference voltage in the voltage comparison will.

A device for generating the reference voltage from an auxiliary transformer can be used a core, a primary winding fed by an AC power source, and a secondary winding whose voltage is the reference voltage in the trip circuit.

The voltages on the trigger winding and the secondary winding are equal and opposite directed.

A simple unrf sensitive training will be

achieved in that the auxiliary winding of the summation current transformer and the primary winding of the Auxiliary transformers are connected in series with each other, and that the secondary winding for the reference voltage and the trigger winding are connected in series. are tet.

A particularly simple design can be obtained in that the summation current transformer and the auxiliary transformer have a common iron core with two magnetic circuits, one of which is the one forms the core for the summation current transformer and the second forms the core for the auxiliary transformer, and that the auxiliary winding is mounted on a part common to both magnetic circuits. whereby the release winding and the secondary winding

development of the auxiliary transformer are connected in series and directed in opposite directions.

It is also possible that the trip winding arranged on the iron core of the summation current transformer i.j one the shutter in a diagonal

containing bridge circuit is connected as a variable inductive resistor. In this case the release winding and the auxiliary winding coincide to form one unit.

As a simple and inexpensive way of supplying the auxiliary winding through which alternating current flows the alternating current for the auxiliary winding attached to the summation current transformer can be passed through Remove the residual current circuit breaker from the protected network, if necessary via a resistor.

The auxiliary winding can also be connected to the protected network via a transformer in order to obtain an adapted alternating current.
To improve customization and achieve

5 6

A high sensitivity of the residual current circuit breaker is reduced (see Fig. 4

circuit breaker, it is recommended to use the auxiliary winding which means: / ac = alternating current fault current,

to be fed by its own generator. Idc = DC residual current, / n = nominal AC

To ensure an absolutely reliable function for fault current).

5 If the summation current transformer of the fault current Use the frequency-matched release and the circuit breaker according to Fig. 2 in front of a DC generator give a frequency, the frequency of the frecurrent consumer 9 feeding rectifier 8 of the network to be protected deviates. This is closed is the possibility of an occurrence The appropriate frequency of the generator can be higher DC residual current particularly large. The mistake, than the mains frequency, e.g. the multiple of the io current circuit breaker is not for such Frequency of the network to be protected. Circuit suitable because it is on a direct current

To an independent of the AC network does not respond.

To obtain alternating current, you can use the alternating In Fig. 3 is a residual current circuit breaker 10

current generator for the auxiliary winding from one for AC residual current according to the in

Feed the direct current network. This embodiment is shown in FIG. 1 and 2 with the reference numerals 1, 4, 5 and

For a residual current circuit breaker, choose the 6 details shown. At the fault current

is to be used in a direct current network. circuit breakers 10 are the three via off switches

With the help of the drawing, the principle of the Er-current consumer is to be connected, of which two,

finding are explained. In the drawing shows 12 and 13, are AC consumers, the third,

F i g. 1 a conventional residual current protection ao 14, one connected to the rectifier 15

switch that operates in an alternating current network with a direct current consumer. The three consumers 12,

AC loads is used, 13 and 14 are each grounded for themselves. Unless at

Fig. 2 a residual current circuit breaker, which in the DC load 14 a DC fault

If an alternating current network is used to which a current is generated, the residual current circuit breaker is used

Do not respond in time to DC consumers via a rectifier because the

is closed, core 1 of the total current converter of the residual current

F i g. 3 the schematic representation of a system circuit breaker 10, a direct current flows which the

with a residual current circuit breaker according to FIG. 1 core 1 premagnetized so that its operating point

and 2, to which two AC consumers and are moved.

a DC power consumer via a rectifier 30 in FIG. 3 is a residual current circuit breaker 10

are connected, shown pre-called effect. In the abscissa

F i g. 4 is a graph of the change of the processing is registered, the current flowing through the core 1 DC-tripping fault alternating current in response to fault current Idc, in the Ordinatenricheinem flowing through the summation current transformer tung of the tripping of the tripping member 5 erfor DC fault current, 35 derliche AC fault current Iac. The nominal

F i g. 5 is the arrangement of a residual current protective AC residual current for tripping when the

is designated in the switch according to the invention in a single-phase DC fault current zero.

AC network with an auxiliary transformer, It can be seen that the required AC power

F i g. 6 shows a second embodiment of a fault fault current for triggering the release 5 with a

Current circuit breaker with a common iron 40 occurring DC residual current increases sharply,

core for summation current transformer and auxiliary transfonra- If a direct current fault current at the consumer

tor, 14 occurs and the working point of the core 1

7 shows a third embodiment of a fault slide, so it is a larger alternating current circuit breaker with only one pre-magnetism fault current at consumer 12 or 13 or both ten summation current transformer, 45 required to the residual current circuit breaker IC

F i g. 8 a fourth embodiment of a fault to respond, and the consumption]

Circuit breaker with a measuring bridge. are not protected according to the setpoint // '

The one shown in FIG. 1 summation current transformer shown A typical case is when a setpoint is present

of the residual current circuit breaker for alternating current 30 mA is specified and the consumer 14 eh

residual current has an annular magnetic core 1. 50 DC residual current of 1 A is produced

through which the three phase conductors and the middle In this case, a trip is eii

point conductor to the 3-phase alternating current alternating current fault current of over 1 A in place of voi

consumer 2 are performed, which is required via the protective line 3 30 mA. The intended protective effect

is grounded The tripping of the residual current circuit breaker 10 arranged on the core 1 is then not

sewicklung4 is connected to the trigger 5, the 55 more given.

operated the switch 6 via a switch lock. The residual current protection shown in Fig. 5

AC mains is grounded via line 7. A switch according to the invention also has an i

from the consumer 2 via the protective conductor 3 flow-ring-shaped magnetic core 1 and a release winding

the fault current generated in the tripping winding4, which is connected to a release, de

a trigger voltage, whereby the trigger element 60 acts on the switch 6. The core 1 of the buzz

and so that the switch 6 is triggered. In the case of current transformers, it also has a special auxiliary tool

a DC fault current is generated in the release 16, which is in series with a primary winding 1

winding 4 is no voltage to trigger the trip of a second transformer, which consists of one

solving organ generated, but a DC pre-ring-shaped magnetic core 18 and a secondary]

magnetization of the summation current transformer causes 65 winding 19, the one with the trigger winding

the one for triggering de? Residual current circuit breaker and with the release 5 is in series and as B <

an increased AC residual current necessary tensile voltage source. The connection is de:

makes, whereby the sensitivity of the type of error that occurs in both windings 4 and 19

7 8

tendency tensions are oppositely directed. Trap becomes a special source of alternating current

The two windings 16 connected in series and supplying the windings 16 and 17 or 25 or a

17 are fed with alternating current; in the example, direct current alternating current converters are used, such as by connecting to two mains conductors via a resistor which is already known for direct current measurement stand 20. One or more 5 (Taschenbuch für Elektromeßtechnik, Siemens AG, Electricity consumers connected by the 1957, p. 140). Between the release coils 4, Residual current circuit breakers should be protected. 19 and the trigger 5, an amplifier can be switched on two power lines will be switched by the magnetic core 1.

guided. Only two mains conductors are shown, but the residual current circuit breaker shown in Fig. 7 works in the same way with io switch has a summation current transformer with one three or four conductors of a 3-phase network. Core 1, an auxiliary winding 26 attached to the line conductor

The alternating current is connected through the auxiliary winding 16 and, and a trip winding 4, from the primary winding 17 on the core 18 induces one terminal end of which is led to a release S equally large alternating voltages in the winding and the second to one of the two power lines. That gen 4 and 19, but since these windings are opposite to each other, the other terminal end of the release is connected to the other are switched, flows through the trigger 5 no Ren power line out. Through the auxiliary winding 26 Current, provided that the current consumer flows a constant alternating current, which in the Wickkeinen Lead fault current. However, if an alternation 4 induces an alternating voltage, which of self-fault current occurs, this causes a change in the voltage derived from the network in circuit 4, 5 tion of the magnetic flux in the core 1. This causes anao to be superimposed. The two windings 26 and 4 Changes in the voltage in the winding 4, so that are preferably chosen so that the circuit 4.5 a voltage arises at the release, which means that it is de-energized if there is no fault current flowing. Occurs Appeals. As a result of the AC fault current, it is triggered in the Resistance 20 determined the impressed current winding 4 a current for triggering the trigger 5 mes remains a change in the voltage induced at the as and the switch 6 switches off. At a Winding 16 without any significant influence. If a DC residual current occurs, the operating point of the DC residual current. so the core 1 is moved in front of the core, so that the alternating voltage, the magnetized and shifted its operating point. induced by the auxiliary winding 26 in the winding 4 This phenomenon does not occur in the second transducer 17, is changed, whereby the trigger 5 a 18, 19, and there is therefore a difference 30 receives voltage different from zero, which is used to switch off the voltages in the trigger winding 4 solution and switching off the switch leads. the and the secondary winding 19, so that as a result of the two circles 26 and 4.5 are from a consultant Voltage trigger 5 responds. their generator is fed if the fault current

The exemplary embodiment shown in FIG. 6, a circuit breaker for monitoring a direct current, corresponds mainly to that in FIG. 5 network shown is used.
Residual current circuit breaker. The two cores 1 and The in F i g. 8 residual current circuit breaker shown

18 are replaced by a core that has two openings, a summation current transformer with the core 1, 21 and 22 to form two magnetic circuits 23 of a winding 4 and a release. The winding and 24 has, with the release winding 4 in magnetization 4 forming a circuit 23 together with a capacitor 27 and the secondary winding 19 in 40 and three resistors 28, 29, 30 being part of a magnetic circuit 24. The two winding bridge circuit. The trigger 5 is in the f inen gene 16 and 17 of the bridge are arranged, while the SpeI-25 is replaced, which is intermediate in the common leg of the bridge solution duich an alternator see the two apertures of the core attached by a single auxiliary winding diagonal takes place on the other diagonal. The parts 4. 27, 28, and therefore belong to both magnetic circuits. The 45 29 and 30 are preferably dimensioned in such a way that the auxiliary winding 25 is connected via the resistor 20 to the fact that, without fault current in the mains conductors, no chips are connected to the mains conductors, and the latter are voltage occurs on the trigger element.

passed through the opening 21 of the core. The alternating current in the winding 4 causes a

F i g. The residual current circuit breaker shown in Figure 6 works alternating magnetization of the core 1.

essentially in the same way as that in FIG. 5 50 conductors an alternating current fault current, then in

shown. the winding 4 induces an alternating voltage, the

Instead of the alternating current to the windings 16, a voltage on the trigger S results in occurs

and 17 or 25 from the mains conductors directly to the DC residual current, then one occurs

To feed resistance, one can also supply direct current bias of the core 1, wc-

use a transformer. There is also 55 due to the inductive resistance of winding 4

the possibility of a separate alternating current source is mitigated and the displacement produced thereby

that is independent of the network. Activate the trigger in the bridge equilibrium

Fig. 5 and 6 assumes that the network conductor can be left.

Lead alternating current. However, it is also possible, if a special generator 31 is used, then the residual current circuit breaker for direct current to 60 can also be used to generate alternating current, the line conductor also being directed through the whose frequency is much higher than that Magnetic core 1 or 23 are guided. In this frequency the network is

1 sheet of drawings

Claims (11)

1 O05 505 claims: 1. Residual current circuit breaker with a summation current transformer, the primary winding of which is connected to the phase lines of an AC system, the release winding of which is connected to a release and the iron core of which is provided with an auxiliary winding fed from an auxiliary source, the same pre-magnetizing auxiliary winding, which release provides a first indication when in A fault current superimposed on the summation current transformer by a ground fault of the alternating current system, characterized in that the primary windings of the summation current transformer in the alternating current leads to the rectifier for additional detection of the earth fault current in direct current consumers (14) which are fed from the alternating current network via rectifiers (15) (15) lie that a pure AC voltage source is connected to the auxiliary winding (16, 25, 26) and that the release (5) connected to the release winding (4) of the summation current transformer in such a way b It is important that it delivers a second display if, as a result of an earth fault in the direct current consumer (14), an equilibrium covering the premagnetization occurs in the summation current transformer! Urom bias is set. 2. Residual current circuit breaker according to claim 1, characterized by its application to one pure direct current network, the conductors of which form the primary windings of the summation current transformer. 3. Residual current circuit breaker according to claim 1, characterized in that an auxiliary transformer with a core (18), a primary winding fed by the AC power source (17) and a secondary winding (19) is present that the auxiliary winding (16) of the summation current transformer and the primary winding (17) of the auxiliary transformer connected in series with one another and that the voltages on the release winding (4) and on the secondary winding (19) are of the same size and in opposite directions in the error-free state (FIG. 5). 4. Residual current circuit breaker according to claim 1, characterized in that the summation current transformer and the auxiliary transformer have a common iron core with two magnetic circuits (23, 24), one of which (23) the core for the summation current transformer and the second (24) the core for the auxiliary transformer, and that the auxiliary winding (25) is arranged on a part common to both magnetic circuits, and that the release winding (4) and the secondary winding (19) of the auxiliary transformer are connected in series and directed in opposite directions (Fig. 6 ). 5. Residual current circuit breaker according to claim 1, characterized in that the auxiliary winding (26) of the trigger winding (4) and is dimensioned so that the trigger circuit induced voltage is compensated in the error-free state (Fig. 7). 6. Residual current circuit breaker according to claim 1, characterized in that the trigger winding (4) arranged on the core (1) of the summation current transformer is connected to a bridge circuit (27 to 30) containing the trigger (S) in a diagonal air variable inductive resistance 7. Residual current circuit breaker according to claim 1, characterized in that the alternating current for the auxiliary winding (16, 25, 26) attached to the summation current transformer the residual current circuit breaker has been removed from the protected network 8. Residual current circuit breaker according to claim 7, characterized in that the auxiliary winding (16, 25, 26) is connected to the protected network via a resistor (20). 9. Residual current circuit breaker according to claim 7, characterized in that the auxiliary winding (16, 25, 26) is connected to the protected network via a transformer. 10. Residual current circuit breaker according to one of claims 1 to 6, characterized in that the auxiliary winding (16, 25, 26) is fed by its own generator (31). 11. Residual current circuit breaker according to claim 10, characterized in that the generator (31) indicates a frequency that is significantly higher than the frequency of the network to be protected is.