SU720557A1 - Timer - Google Patents

Description

I

The invention relates to automation and can be used in relay protection and automation of power systems.

Known semiconductor time relays, built on the principle of recalculation, pulses and containing a pulse generator, a scaling circuit and a decoder with a block of switches and actuators l. However, they are complex in design. Electromechanical time relays are not accurate enough 2.

Closest to the proposed relay is a multi-stage (software) time relay containing one time; specifying an RC circuit, to which cher.rection diodes are connected, by the number of CTyneHsAj comparators with their own sources of reference voltage and executive elements 3.

Such a time relay is characterized by relatively low reliability due to the complexity of the circuit, and a large number of comparators connected simultaneously to the time of the master KS circuit increases leakage and thereby reduces the accuracy of the relay and reduces the capacity utilization time of the master circuit.

In addition, with a small difference in the settings of the neighbor of the xy steps, due to additional errors and scattering of time exposures, a violation of the sequence of their operation can be observed.

The purpose of the invention is to improve the reliability of the relay by simplifying the circuit, as well as improving the accuracy of time delay and expanding the functionality of the relay.

This is achieved by the fact that the software time relay, which contains the time specifying an RC circuit connected to one comparator output, resistors in terms of the number of stages, which form the voltage sources connected to the second input of the comparator, the power source and the actuators, are additionally introduced elements AND and OR, with each of the resistors of the sources of the voltage being connected to the power source through a circuit of successively connected contacts of the executive elements of the preceding ones, which close when they are activated contact of the actuator of its stage, which opens when it is triggered, the input of each of the actuators is connected to the output of the element OR of its stage, and the output to its first input, the second input of the element OR of the first stage is connected to the output of the comparator, and from the second inputs of the elements OR of the subsequent stages to the output of the element AND its own stage, each of the first axes of which are connected to the output of the comparator, and each second input to the output of the actuating element of the previous stage. In addition, each of the AND elements mentioned is provided with a delay of & output signal. The drawing shows the functional SRI program relay diagram for. couple ex arthen. To the input of comparator 1 there are connected an l RCA circuit, consisting of a resistor 2 and a capacitor 3, and one of the sources of the reference voltage, a ciocte circuit: of a constant resistor 4 and variable resistors 5, 6, 7 and 8 adjusting the time delay of the steps The output of the comparator 1 is connected to the first entrances of the eschyments OR 9, AND 10, AND 11 and I12, and the outputs of the elements AND lOt AND 11 n And 12 are connected to the first steps of the elements OR 13, OR 14, and OR 15. The outputs of the elements OR 9 „OR 13, OR 14 and OR 15 are connected to the actuators of the executive elements of the stages: 16 (first stage), 17 (second stage), 18 (third stage) and 19 (fourth stage), the outputs of which are connected respectively to the second input of the elements OR of their stage and the elements of the subsequent stage, and that to the inputs of the control voltages of the reference voltages connected to one or another source reference voltages (resistors 5, 6, 7, and 8) and power supply. The circuit works a trace in a skinny way. When the power is reached, the time delay set begins. When the voltage on the clock signal of the 1st stage is equal to the reference pulse of the first stage, determined by the size of the resistor 5 connected at this time to the power source, the comparator 1 is activated and through element I / B1 9 turns on the actuator 16 first stage. The last signal passing through the second trip of the element OR 9 becomes self-blocking, and also prepares the element AND 1O for passing the control command to the actuator of the second stage 17, In addition, the switch 20 k, the comparator 1 is connected instead of the source voltage of the first stage. the source of the reference voltage of the second stage. At the same time, the signal at the comparator 1 disappears. When the voltage on the capacitor 3 compares with the new value of the reference voltage taken from the resistor 6, the comparator 1 is activated again and through the prepared element AND 10 turns on the actuating element of the second stage 17, which through the element OR 13 is self-blocking and switches off Comparator 1 is a second-stage reference voltage source (resistor 6), and connects the next-stage reference voltage source (resistor 7). In this case, the signal at the output of comparator 1 disappears again and appears again when comparing the voltage level for the time of the master capacitor 3 with the level of the new value of the reference voltage on the resistor 7. Then the process repeats. To eliminate the possibility of simultaneous actuation of the actuating elements, the neighbor X of the stages, the elements 10 and 11 and 11 12 are provided with a delay in the appearance of the output signal, the magnitude of which is determined by the time the signal disappears at the comparator output after the actuating element of the corresponding stage has been activated. In the proposed time relay, the connection of only one comparator to the time of the descending RC circuit greatly increases the accuracy of operation and the capacity utilization factor (specific time delay); the sequence of operation of the steps is not disturbed even if an error is set in the time delay: the subsequent stage can only work after the operation of the previous step, 11 which is necessary in relay protection in a number of cases.

Claims (2)

Claim 1. A software time relay, which contains a time-giving RC circuit, connected to one output of the comparator, resistors by the number of steps, forming reference voltage sources connected to the second input of the comparator, a power source and actuators., Characterized in that, in order to improve the accuracy and reliability of operation, as well as expand the functionality, it is additionally equipped with AND and OR elements, with each of the resistors of the voltage reference sources connected to the power source through a circuit from the Remarkably: the connected closing contacts of the actuators of the previous stages and the NC contact of the actuator of its stage, the input of each of the actuators is connected to the output of the OR element of its stage, and the output is connected to its first input, the second input of the OR element of the first stage is connected to the output of the comparator, and each of the second inputs of the OR elements of the following steps - to the output of the AND element of its own stage, each of the first inputs of which is connected to the output of the comparator, and each of the second inputs - to the output to the actuator of the previous stage. 2. Time relay in π. 1, characterized in that each of the mentioned elements AND is equipped with a delay for the appearance of the output signal.