SU866634A1 - Current relay with dependent operation time - Google Patents

Description

one

This invention relates to electro. technology, namely, relay protection devices with a dependent characteristic of time of operation and can be applied to protect electric motors and power lines.

A current relay with a time dependent characteristic is known, which contains an AC converter into a proportional constant voltage, a resistor-capacitor integrating circuit, a clock generator, which sets the frequency of charging current pulses into the integrated circuit, the duration of which depends on the current level passing through the protected object, and a threshold organ, which fixes the voltage level on the capacitor of the integrating circuit 1.

The disadvantage of the device is a reduced accuracy of operation at a current equal to the relay operating current, which corresponds to the maximum response time. This makes it difficult to match the characteristic of the protection time at the current of protection operation with the overload characteristic of the fuse.

Since the introduction of a large margin when setting up protection may damage the protected object or an unacceptably long protection response time.

The closest in technical essence and the achieved result to the present invention is a current relay with a dependent characteristic of operating time, containing an AC converter into a constant voltage proportional to it, the input of which is connected to the first input of the decisive amplifier 5 with an adjustable gain factor. the input of which is connected to a constant voltage source, the output is connected to the input of the starting unit, the first input of the unit

20 whose second input is connected to the output of the triangular voltage generator, and one of the terminals of the potentiometer, the first input of the controller and

25 control input of the first electronic, one clamp of which is connected-. not with a moving potentiometer contact, another terminal with the second input of the adder, the output of the latter is connected to the input of the resistive-capacitor integrating unit, a second controlled electronic switch is connected parallel to the capacitor of the specified unit, the control input of which is connected to the output of the starting unit, the output resistor the capacitor integrating unit is connected to the first input of the reacting unit, the second input of which is connected to the source of the reference voltage, the output of the reacting unit is the output of the relay e current 2.

In the known device, the capacitor of the integrating unit is periodically charged and discharged through. one and that; the same resistor with multi-pole rectangular voltage pulses, the ratio of the lengths of which grows with increasing current, due to which the time response characteristic is obtained. Regulation curve shape xa. characteristics c. The range of currents from the relay operation current to the current corresponding to the transition, an independent part of the characteristic, is provided by introducing a partial dependence of the discharge voltage on the regulated voltage proportional to the difference between the input current and the relay operation current.

At an input current equal to the relay actuation current, the charge and discharge voltage pulses are equal in magnitude and duration. This allows one to obtain a sufficiently large value of the maximum response time of the relay.

However, a disadvantage of the known device is that the relay maximum response time cannot be accurately set, since at an input current equal to the relay activation current, it tends to infinity, as a result of which this time can be excessively long and not correspond to the required relay response time this current, which reduces the reliability of the relay.

The purpose of the invention is to improve the accuracy of work by improving the matching time of the current characteristics of the relay and the protected object.

This goal is achieved by the fact that in a current relay with a dependent characteristic of time of action, containing an AC converter in proportion1 | (Ionic constant voltage to it, the input of which is connected to the terminals of the protected electrical installation, the output to the first input of a decisive amplifier with adjustable gain, the second input of which is connected to a constant voltage source, the output is connected to the input of the starting unit and the input of the unit the comparison, the second input of which is connected to the output of the generator of a triangular voltage, a potentiometer, one of the terminals of which is connected to a common, common point of the circuit, a moving contact to one of the terminals of the first controlled electronic key, output. —the starting unit is connected to the control input of the second electronic, connected in parallel to the capacitor of the resistor-capacitor integrating unit, the output of which is connected to the first input of the reacting unit) the second input of the latter is connected to the reference voltage source, the output of the reacting unit is the output of the current relay, additionally introduced are a series-connected DC voltage source and a third controllable electronic key, a NOT element, a discharge resistor, an operational device or switch and two-way switch,

0 the moving contact of the latter is connected to the output of the decisive amplifier with adjustable gain, the fixed contacts to the inverting and non-inverting inputs of the operational amplifier, the output of which is connected to another terminal of the potentiometer, the input of the HE element and the control input of the third electronic switch, the second the clamp of which is connected to one of the terminals of the resistor of the resistor-capacitor integrating unit; another is connected to the output of the latter through a discharge resistor their first controlled electronic switch,

5 whose control input is connected to the output of the element NO.

FIG. 1 shows the current circuit diagram; Fig. 2 shows the diagrams of the stresses in the characteristic strings of the circuit in Fig. 3 - time characteristics of the current relay. ;

The time dependent current relay contains an AC to 1 converter

proportional voltage, decisive amplifier 2 with adjustable gain, source of constant voltage U, determining dc current of relay operation, starting block 3, unit 4 of comparison, generator 5 of triangular voltage, potentiometer 6, first controlled electronic switch 7 , the second controlled electronic switch 8, the capacitor-capacitor unit 9, made in the form of a series-connected resistor 10 and a capacitor 11, the reacting unit 12, the reference voltage source UQ, additionally entered a constant source the third voltage, the third controllable electronic switch 13, the discharge resistor 14, the element 15, the operational amplifier 16, the two-position switch 17.

The device works as follows.

Converter 1 forms a constant voltage, proportional to it, from controlled alternating current Ig. This voltage is supplied to the first input of the decisive amplifier 2 with an adjustable gain factor, to the second input of which the operating voltage of the relay U-j is applied, corresponding to the current 1 relay 1 is activated. The input voltage of the U-solver amplifier 2 is proportional to the voltage difference (1 K (and - UOP), where K is the gain factor of the solver amplifier,

Voltage U2 is applied to the input of the starting unit 3, the first input of the comparison unit 4, and to the moving contact of the two-position switch 17. The starting unit 3 is designed as a null indicator, the output signal of which changes discretely when the sign of the output voltage changes. In the event that the input current is triggered, the relay start-up unit 3 operates, and acts on the second controlled electronic storage unit 8, which decouples the capacitor 11 in the resistor-capacitor integration unit 9 and allows the charge of the capacitor 11 to be charged through the resistor 10. The comparison unit 4 compares the voltage Uj- from the output of the generator of a triangular voltage 5 with voltage U at the output of decisively amplifier 2 and. has two discrete values of the output signal: one for U 7 U l the other for u and y

As can be seen from Fig. 2, in the time intervals (CD), when 7 U j, the voltage Id from the output of the comparison unit 4 is fed to the input of the element NOT 15 and to the control input of the third electronic key 13, with the first control The latchable electronic key 7 is in the disconnected state, since the control element HE does not have a control signal and the third controllable electronic key 13 is turned on. In this case, a pulsed charge of capacitor 11 (voltage U) from a constant voltage source through a resistor 10 occurs.

In the time intervals (), when Uj 5: the state of the first and third controlled electronic keys 7 and 13, respectively, is reversed. Due to this, a pulse discharge of the capacitor 11 occurs through the discharge resistor 14, the first controlled electronic switch 7 and potentiometer 6. To adjust the discharge intensity of the capacitor 11, which, in turn, allows the time characteristic of the relay to be changed by potentiometer 6 voltage is supplied from the output of the operational amplifier 16, which oji .nim from the inputs {depending on the position of the moving contact of the two-position switch 17) is connected with the output of the decisive amplifier 2 with adjustable gain, with At. current, greater than the switching current of the relay, the voltage U. gradually increases and when it reaches the value VQ, the reacting body 12, which supplies

Q command to disable the protected object.

At the lowest position of the movable contact of the potentiometer b, -dn., The voltage U applied to it is close to zero and does not affect the character of the discharge.

5 capacitor 11. The ratio of the charge time CS (p and discharge 1pc, capacitor 11 during each period following the output signal of the generator 5 triangular voltage minimum

0 at an input current equal to the ICP relay actuation current and increases with increasing input current.

As can be seen from the diagrams in Fig. 2, starting from a certain value of voltage and, corresponding to the transition of the characteristic of the relay to the independent part (current i), the capacitor 11 is charged during the whole time of the relay,

0 which corresponds to the minimum response time of the relay tj (Fig. 3). At current values in the interval between Igp and 1dise, with an increase in the current Ig, the ratio of the charge time increases.

- and the discharge of the capacitor 11 and, accordingly, the response time of the relay is reduced, due to which the dependent characteristic of the operating time of the current relay is obtained.

0, in the case of UO, the time characteristic of the relay is obtained, the character is determined by the values of the cp voltage and the resistance of the resistors 1and 14 and the capacitance of the capacitor 11 (curve 18 in Fig. 3). The nature of this dependence can be changed by introducing into the discharge circuit of a capacitor 11 a voltage source depending on the input level.

0 current relay. This voltage source is obtained with a corresponding adjustment of the potentiometer 6, to which the operational amplifier 16 is loaded, and a certain position of the two-position switch 17. If the voltage U5 is opposite to the voltage Ujg, then the discharge of the capacitor 11 is more intense than in the case of Ug O, which leads to an increase in the slave time delay) of the relay (curve 19 in FIG. 3). With a further increase in the voltage level Ug, at the same value of the input current, the delay time of the relay becomes even longer (curve 20

Claims (2)

5 in FIG. 3). In case of coincidence of the polarities of the stresses and. and Ug the discharge of the capacitor 11 is less intense, than in the case of Ug 0, which leads to a decrease in the relay response time (curve 21 in FIG. 3). In this case, due to a further increase in the voltage level Ug at the same input time current, the relay becomes even smaller (curve 22 in FIG. 3). The time characteristic of the current polarity Ug is required to obtain a predetermined change in nature due to a certain position of the switch 5. Therefore, this relay can clearly record the maximum and minimum response times and also obtain the necessary dependence of the relay time from the input current. The adjustment of the parameters of the time characteristic of the relay is carried out as follows. The value of the relay actuation current p is determined by the level. The current value 1kez / corresponding to the transition characteristics in the independent part. with the response time, is determined by the gain of the decisive amplifier 2, adjusted in such a way that the voltage J at I is not equal to the amplitude of the voltage U5. The minimum response time of the relay 1 is controlled by the resistance of the resistor. Resistor 10, and the maximum with the resistance of the discharge resistor 1. Finally, the required curvature of the characteristic, set by the response time at a certain current in the range between 1., and, is obtained by adjusting the level taken from potentiometer 6 and, if necessary, changing the position of the two-position switch 17. The proposed relay allows more accurate, especially when the input current is equal to the relay operation current, to get his time is a tokovuk characteristic; which improves its coordination with the characteristic of the protected object. Claims of the Invention A current relay with a dependent characteristic, operating time, contains an AC converter into a proportional constant voltage, the input of which is connected to the terminals of the protected electrical installation, the output is connected to the first input of a power amplifier with an adjustable gain factor, the second input is connected to a constant voltage source, the output is connected to the input of the starting unit and the first input of the comparison unit, the second input of which is connected to the output of the triangular voltage generator, sweat A thermometer, one of the terminals of which is connected to a common point of the circuit, a movable contact to one of the terminals of the first controllable electronic key, the output of the starting unit is connected to the control input of the second electronic key connected to a capacitor of the resistor-capacitor integrating unit, the output of which is connected. with the first input of the reacting unit, the second input of the latter is connected to the reference voltage source, the output of the reacting unit is the output of the current relay / characterized in that, in order to increase accuracy of operation, by improving the matching time of the current characteristics of the relay and the protected object, additionally introduced are series-connected DC voltage sources and a third controlled electronic key, a HE element, a discharge resistor, an operational amplifier and a two-position switch, the moving contact of the latter connected to the output of the decisive amplifier with adjustable gain, fixed contacts to the inverting and noninverting inputs of the operational amplifier, the output of which connected to another terminal of the potentiometer, the input of the element NOT and the control input of the third electronic switch, the second terminal of which is connected to one of the terminals of the capacitor-integrated integrating unit, are connected to the output of the comparator unit, another terminal is connected to the output of the latter through the discharge resistor the first controlled electronic key, the control input of which is connected to the output of the element NOT. Sources of information taken into account in the examination 1. UK Patent No. 1423748, cl. And 02 H 3/08, 1976. 2. GCCP copyright certificate according to application I 2813062 / 24-07, cl. H 02 H 3/08, 1979. Y Z Ak t-d inai№ I min tpui.3