DE1124587B - Time delay device for electrical protective relays - Google Patents

Description

The invention relates to a time delay device for electrical protective relays, whose Trip time depends on the size of a DC actuation signal, which in turn is functionally dependent is of the overcurrent or overvoltage occurring in the circuit to be protected a capacitor that can be charged via a resistor and a rectifier and is parallel to the trip circuit lies.

In a known delay relay, which is intended in particular for railway safety devices is, the charging current for the capacitor flows in the forward direction through the rectifier, the here as a blocking cell between the capacitor and a relay is arranged in such a way that it is from Charging current of the capacitor flows through in the forward direction, but that the discharge current of the Capacitor due to the blocking effect of the rectifier essentially by a parallel to the Capacitor lying resistor flows. The time constant of the known circuit essentially depends apart from the dimensioning of the capacitor, only depends on the size of a charging resistor, whereby this resistance and thus the time constant are current-dependent.

The aim of the invention is to create a time delay device for an electrical protective relay, which has an adjustable high time constant and the circuit with high operational reliability of the protective relay.

For this purpose, according to the invention, the time delay device is that mentioned at the beginning Design designed in such a way that the rectifier in reverse direction opposite to the polarity of the Actuating signal is switched and causes a delayed charging of the capacitor.

A resistor conductive in two directions can be connected in parallel to the rectifier, its Resistance decreases when the voltage drop across it increases. The adaptation of the relay characteristics can then be effected in that an adjustment is made to the currents flowing through this parallel connection of rectifier and resistor flow. The setting of the currents can be done caused by the fact that the leads are connected to different taps of the rectifier will.

According to an exemplary embodiment of the invention, a voltage can be present at the output terminals of the time delay device which is composed proportionally of the voltage across the capacitor and a voltage drop across a time delay device
for electrical protection relays

Applicant:

The English Electric Company Limited,
London

Representative: Dipl.-Ing. C. Wallach, patent attorney,
Munich 2, Kaufingerstr. 8th

Claimed priority:
Great Britain dated June 11, 1959 (No. 20 036)

Eugeniusz Antoszewski and John William Frederick,

Stafford (Great Britain),
have been named as inventors

another resistor in series with another rectifier connected in the reverse direction to the Input terminals is so that the time delay effect of the capacitor is rendered ineffective and an instantaneous relay triggering in the event of unusually high actuation signals is caused by that the resistance value of the further rectifier suddenly drops in the event of a high overcurrent. Rectifier, which have a suitable characteristic for this purpose are copper oxide or selenium rectifiers.

A tapped linear resistor can also be connected to the charging circuit of the capacitor, which enables a further adjustment of the operating characteristics. For quick relay reset can parallel to the charging rectifier and the charging resistor a further rectifier and a further resistor be connected, said further rectifier also in reverse direction and a better barrier effect than that

209 517/329

Has charging rectifier. Rectifiers that have a suitable detector level, while the converter Γ 4 has one Nete characteristic for this additional DC part of the power supply device for the measuring converter have silicon or germanium and trip circuit forms.

rectifier. The converter Γ 3 is designed and loaded in such a way that

To provide a low resistance path for the 5 to saturate at a lower input current Creating capacitor discharge current is more useful than the converter Γ 2, and the secondary windings moderately in parallel with the input terminals one of these two converters produce equal to each other another resistor switched. EMFs when the transducers are unsaturated. So will

The above-described time delay device when the secondary windings are connected against one another generally has a characteristic of the form I "-t io these converters T 2 and Γ 3 an output emf er = constant, where n> l output signals of the Wandritik desired, in which n 'is l, parallel coupler Tl may be zero. These output emf is one of the input terminals in the reverse direction a WEI rectifier supplied to B 1, the output signal more excellent rectifier and in series with these, a to - of the overload detector, the terminal-tapped resistor labeled α is switched, to whose 15. This output signal is switched on by tapping one of the output terminals. Capacitor C2 is smoothed. The load on the wall is Resistances R 1 or R2 process signal with increasing overcurrent signal is seen to be smaller and also as a load on the converter In this arrangement, a T 2 and an adjustable resistor P1 can be used as a rectifier, through which low output signals of the converter Π are provided in the case of selenium or copper oxide rectifiers. Output signal of the overload detector on the zero

The invention also relates to an electrical protection value that can be adjusted. The output circuit relay, which with a time delay device of the converter also has a capacitor C1 according to the design described above, which can allow phase differences between the converters. This relay has a trip 25 and load circuits corrected to the balancing device, which responds to the output voltage of the EMFs induced between the secondary time delay direction. windings of the two converters Tl, T3

This can result in an overload or overvoltage. The setting of the relay is provided by the detector that determines the value of two input transducers at which the transducer has Γ 2 , the secondary windings of which are saturated with respect to each other, but the relay operating range can be switched through, with these transducers such a change in the taps of the Primary winding of the wall have different saturation characteristics that lers Π are changed via which the current of their combined output EMFs is fed to the overload detector under normal input signal. If this input signal is zero, and a lower setting exceeds a specified value, different EMFs are generated when the rectifier Bl to be protected generates a voltage, because as a result System is disturbed. Workers in the area of saturation of the resulting

Further details and advantages of the invention Output of converters Γ 2 and Γ 3 not equal to zero will emerge from the following description of FIG. 1, and at the terminals α there is a direct current exemplary embodiment on the basis of the drawing. In 40 output signal that is proportional to the overcurrent of the Drawing shows component of the input signal of the overload detector

Fig. 1 is a circuit diagram of an electrical overcurrent gate.

protection relay with an embodiment of the invention. The terminals α of the overload detector are on

time delay device according to the invention, with an equal terminal α of the time delay device

Overload detector stage, with a measuring and output 45 connected. The purpose of this device is the release circuit and with a power supply device is to provide a signal at its output terminals b

for the measuring and trip circuit, generate the supplied from the terminals α

Fig. 2 is a circuit diagram of another execution signal dependent, but compared to these time-delayed

form of the time delay according to the invention is delayed, namely in time proportional to the direction with the characteristic / ² · ί = constant, 50 size of the input signal. The measuring and Aus-Fig. 3 a circuit diagram of a further execution release circuit to which a time-delayed connection is made via terminals b

example of the time delay output signal according to the invention is supplied, comes into action,

furnishings. when this output signal has a predetermined

In Fig. 1 the circuit of a time-overcurrent value is exceeded, and causes the response of a

relay divided into four sections. In practice 55 relays A.

these sections form individual units of a The measuring and tripping circuit has two German

Systems that are electrically connected to each other. niumtransistors TRl, TR2 , each forming a stage. The invention relates mainly to that of a two-stage amplifier. A Klem the formation of the time delay means including a men b supplied input signal is representing via one of these sections. 60 germanium diode SS the base emitter circle of the

According to FIG. 1, one of the other down transistor TR1 is supplied. This transistor is from the section-forming overload detector stage a current of the pnp type and with its emitter to a converter Tl , whose primary winding is connected to the movable tap of a potentiometer P 2 and connected according to the current that is between two resistors RH, being aroused in this protected circle. The secondary 65 R 12 on the high voltage side of the first stage of the primary winding of the current transformer Γ1 energizes the primary amplifier TR 1. In terms of high voltage, the windings of three further current transformers T2, T3 and the measuring and tripping circuit are fed via the c -Γ4, from which the transformers T2, Γ3 in the overloaded terminals. To get to the first step

To make it less sensitive to changes in this high-voltage supply, a limiting circuit is provided which has a resistor R 13 and a Zener diode 56, which stabilizes one

operating time - this is understood to mean the time required to charge the capacitor C 3 to a value at which the relay A responds - in the order of one hour

High-voltage supply for the first stage of the supply 5 can be obtained, stronger is obtained. A temperature-dependent, with the time delay shown in Fig. 1

TR denoted resistor is located in the collector circuit device is also a precaution for a fast of the transistor TR 1 and supplies the output signal reset and an instantaneous relay actuator of the first stage of the amplifier, which is used as an input in the event of an unusually high overcurrent input signal to the base-emitter circuit of transistor 77? 2 OK signals hit. The working characteristic of the Rezugef, which is of the pnp type. The relay depends on the characteristics of the DC relay / 4 is in the collector circuit of this Tran- richter53 as by non-linear resistance NL sistor TR2. A capacitor C4 is located between the existing circuit and resistor R 7. In the case of the collector and the emitter of the transistor, in order to reset the relay, the resistor R 7 would protect these against high surge voltages, 15 cause a time delay. In order to switch off this delay during the switching process by the relay A tion, a shunt path has to be generated in advance. In operation, the tap is seen, in which a silicon or germanium potentiometer P1 through a voltage limiter rectifier 52 in series with a resistance circuit, which is through a diode 56 and one. This resistor R 8 can, compared with the resistor R 13 is formed, kept at a stable 20 the resistance value of R 7, a potential that is relatively stable. The potential of this tap loading have low resistance value and does agrees to the threshold value of the signal at the Termi- to be only so great that the charging current to a men b, which makes the transistor TR1 conductive. appropriate value is limited. The in the temperature-dependent resistor TR in A resistor R 5 is above the input

The current generated at this conductivity level is picked up and amplified by 25 terminals α of the time delay device and the transistor TR 2 , and when resetting a discharge path, this transistor then actuates relay A. The

Germanium diode 55 reduces the collector-base effect when the overcurrent, for example, four times the current of the transistor TR 1, which assumes the inverse value of the current that is required for actuation through the time delay circuit back 30 of the relay, is flowing for the purpose of creation. a sufficiently large output signal to the

The task of the temperature-dependent resistor clamps b an additional signal to that of which it is, in the measuring and tripping circuit, a temperature capacitor C 3 added signal supplied. This temperature compensation is created to compensate for the additional temperature signal stems from a resistor / 6 effects of the transistors. This 35 ago, which is in series with a selenium or copper compensation is primarily necessary when oxide rectifier 51 is connected and a transistor such. B. the transistor TR 1, excited by rectifiers from the input terminals α from a small input current is controlled because is. In the case of relatively small overcurrent signals under these circumstances, where the input current in the rectifier S1 offers a high resistance, the same order of magnitude as the reverse current of the 40 compared to the resistor R 6, and therefore the transistor, the high temperature dependency does not benefit this circuit the output signal of the reverse current is of major importance. the time delay device. At high over-The power supply device consists of the current signals, however, the resistance of the DC converter Γ 4, the one through the resistance richtersSl from, so that the potential of the resistor R 16 and the rectifier bridge B 2 formed load 45 status R 6 for relay operation more meaningful feeds. The capacitors CS and C 6 are above and at unusually high overcurrent signals

can generate an output signal at the terminals b which actuates the relay A without being subjected to the delay effect of the capacitor C 3. In order to take precautions against extremely high overloads, a Zener diode 54 is in parallel

the output and input terminals of the rectifier B 2 in order to smooth the current and to protect the transistors of the measuring and tripping circuit against excessive shock effects.

The time delay device shown in Fig. 1 has a capacitor C 3, which by an input signal fed via the terminals α via a selenium or copper oxide rectifier 5 3 and a resistor i? 7 is being charged. In parallel with 55 the rectifier 53 there is a non-linear resistor NL. This resistance can, for example, be of the type sold under the trade name »Metrosil«

connected to the resistor R 6 in order to protect the transistor TR 1 of the measuring and tripping circuit from overloads.

The operating characteristics of the relay can be set by connecting to various taps at the rectifier 53 and the resistor i? 7.

Different relay operating characteristics

has become known. A resistor made from this material has a resistance value of 60, which can also be achieved through modified circuits, which can be reached with increasing voltage across the. So the time delay device resistance can drop. The rectifier 53 is, for example, the circuit shown in FIG. 2 on the basis of the current in the reverse direction supplied by the rectifier S1 of the overload mode, which is essentially of the form I ² · t = constant switches. The rectifier 53 thus sets the input 65 has. In this expression / denotes the size of the output signal in relation to a high resistance overcurrent signal and t the operating time of the relay shape

Ι ^Λ ■ t - constant, where η is slightly less than 1. The setting can be made in the same way as for the standardized overcurrent relay, which is described in British Standard Specification 142.

In this exemplary embodiment, the potential drop is applied over part of a shunt to the capacitor potential. This shunt has a selenium or copper oxide rectifier S10 which is connected in series with a tapped resistor R 20 to the terminals α. The tap of this resistor R 20 is connected to the output terminal b .

The rectifier 510 has a relatively high impedance value compared to low overcurrent signals, which means that the potential across the capacitor C 3 differs only slightly from the potential across the terminals b. However, the rectifier 510 has a relatively low impedance to high overcurrent signals and the resistor R 20 is therefore more effective in creating a potential difference between the lower terminal b and the corresponding end connection of the capacitor C 3. The consequence of this is that the output signal appearing at the terminals b becomes smaller than the capacitor potential as the overcurrent signal increases.

Claims (19)

PATENT CLAIMS: 1. Time delay device for electrical protective relays, the tripping time of which depends on the size of a direct current actuation signal, which in turn is functionally dependent on the overcurrent or overvoltage occurring in the circuit to be protected, with a capacitor that can be charged via a resistor and a rectifier and that runs parallel to the tripping circuit is, characterized in that the rectifier (S3) is switched in the reverse direction against the polarity of the actuating signal and causes a delayed charging of the capacitor (C 3). 2. Time delay device according to claim 1, characterized in that a resistor (NL) which is conductive in two directions is connected in parallel with the rectifier (S3), the resistance value of which decreases when the voltage drop across it increases. 3. Time delay device according to claim 2, characterized in that the relative currents which flow through the resistor (NL) and the rectifier (S3) are adjustable. 4. Time delay device according to claim 3, characterized in that for the purpose of adjustment of the relative currents taps are provided on the rectifier (S3). 5. Time delay device according to one of the preceding claims, characterized in that there is a voltage at the output terminals (b) which is proportionally composed of the voltage across the capacitor (C 3) and a voltage drop across a further resistor (R 6), which is connected in series with another rectifier (S1) connected in the reverse direction to the input terminals (α), so that the time delay effect of the capacitor (C 3) is canceled and an instant relay triggering is effected in the event of unusually high actuation signals. 6. Time delay device according to claim 5, characterized in that the rectifier (Sl) is a copper oxide rectifier. 7. Time delay device according to claim 5, characterized in that the rectifier (Sl) is a selenium rectifier. 8. Time delay device according to claim 5, characterized in that the resistor (R 6) has a linear resistance characteristic. 9. Time delay device according to claims 1 to 8, characterized in that the capacitor (C 3) via the rectifier (S3) and a tapped linear resistor (jR7) is charged and that another rectifier (S2) is provided for discharge, which has a better blocking effect than in the blocking direction the rectifier (S3). 10. Time delay device according to claim 9, characterized in that the rectifier (S 2) is a silicon rectifier. H. Time delay device according to claim 9, characterized in that the Rectifier (S2) is a germanium rectifier. 12. Zeitverzögerungsemrichtung according to claims 1 to 11, characterized in that a resistor (R5) is connected in parallel to the input terminals (α), which provides a path with low resistance for the capacitor discharge current when the relay is reset. 13. Time delay device according to claim 1, characterized in that parallel to the input terminals (a) in the reverse direction a rectifier (SlO) and in series with this a tapped resistor (i? 20) are connected, at whose tap one of the output terminals (b) is switched on (Fig. 3). 14. Time delay device according to claim 13, characterized in that the Rectifier (SlO) is a selenium or copper oxide rectifier. 15. Electrical protection relay with a time delay device according to claim 1, characterized in that a relay release device is provided which is responsive to the output voltage of the time delay device. 16. Electrical protection relay according to claim 15, characterized in that an overload or overvoltage detector is provided which has two input transducers (T 2, Γ 3) whose secondary windings are connected against each other, and that these transducers have such different saturation characteristics that their combined output EMFs under normal operating conditions in the system to be protected by the relay are zero and that a different emf is generated when the system to be protected has abnormal conditions. 17. Electrical protection relay according to claim 16, characterized in that the detector is an overload detector and the input converters (T 2, Γ 3) are current converters. 18. Electrical protective relay according to claim 17, characterized in that a bundle resistor (Cl) lies in parallel with the secondary winding of a converter, the phase difference between to correct the converters. 19. Electrical protection relay according to claim 18, characterized in that the reactance is a capacitor (Cl). Publications considered: German Patent No. 754 059. 1 sheet of drawings ι 209 517/329 2.