CS219957B1 - Connection of the circuit of the indication of the disconnection,short circuit and resistance alteration of the input circuit of the electric protecting device - Google Patents

Description

This principle of capacitor discharge is used mainly for high speed, small dimensions and especially for low energy consumption during operation. The output circuit of the belay device is not live when the device is in operation and all of the device inputs are within the given limits. At this time, there is no information about the state of the output circuit, although the state of the output circuit is of paramount importance for the proper functioning of the belay device. In case of disconnection, short-circuits and unauthorized change of resistance of the output circuit, the circuit breaker of the device does not fulfill its function if necessary.

These disadvantages are eliminated by the circuit of the trip indication. short circuit and unauthorized changes in resistance of the output circuit of the electric breaker device according to the invention. The principle of the invention is that the output of the switching circuit of the belay device is connected both to the first input of the amplifier and to the body of the belay device via the first, second and third resistors. The output of the stabilized voltage source is connected to the connector of the first and second resistors and the second input of the amplifier is connected to the connector of the second and third resistors. The output of the amplifier is connected via a comparator to the first input of the logic circuit, the second input of which is connected to the output of the DC supply voltage with a high internal resistance, and whose third input is connected to the control input of the switching circuit. The output of the logic circuit is connected to the input of the indication circuit.

The advantage of wiring the indication circuit according to the invention is continuous indication of disconnection, short circuit and unauthorized change of resistance of the output circuit of the protection device, which is necessary for perfect function of the protection device in its operating mode. function of protection of the protected device.

An exemplary embodiment of the invention is shown schematically in the drawing, which represents the circuit of the circuit breaker itself and the indication circuit according to the invention.

In the protection device 7, the output of the DC supply voltage U2 from the high internal resistance source is connected to the frame of the protection device 7 via a capacitor C from which the power output of the switching circuit 5 is supplied. an electronic circuit by an electrical physical quantity sensor from a fused device, the output of which is connected to the frame of the protection device 7 via a power element 6. The output of the switching circuit 5 is connected to the first input of the amplifier 1 and to the first, second and third resistors R1. R2 and R3 are connected to the frame of the protective device 7. The output of the stabilized voltage U1 is connected to the first resistance R1 and the second resistor R2, and the second amplifier 1 is connected to the second resistance R2 and the third resistor R3. comparator 2 on first input logick his circuit 3, whose second input is connected to the output of the DC supply voltage U2 with high internal resistance, and whose third input is connected to the control input of the switching circuit 5. The output logic circuit 3 is connected to the input circuit indicator fourth

The circuit of the indication circuit 8 according to the invention is characterized in that the output circuit of the electric circuit breaker 7 is the fourth branch of the Wheatstone bridge formed by the power member 6 and the electrical connection between it and the output of the switching circuit 5 on one side thereof. its other side. The first branch of the Wheatstone bridge is formed by a first resistor R1 connected by its first terminal to the output of the switching circuit 5 and its second terminal to a stabilized voltage U1 and to the first terminal of the second resistor R2 forming the second branch of the Wheatstone bridge. to a first terminal of the third resistor R3 forming a third branch of the Wheatstone bridge, wherein the second terminal of the third resistor is connected to the frame of the belay device 7. The Wheatstone bridge has a diagonal formed by interleaving the first and fourth branches. The first link is connected to the first input of the amplifier 1 and the second link is connected to its second input. Amplifier 1 amplifies the voltage proportional to the weighting of the Wheatstone bridge. The output voltage of the amplifier 1 is compared in the comparator 2 of the unauthorized change in resistance of the output circuit of the belay device 7 with a voltage that corresponds to the limits of the allowed weighting of the Wheatstone bridge. The output circuit of the circuit breaker 7 consists of a power member 6 and an electrical connection between it and the switching circuit 5 and between it and the frame of the circuit breaker 7. The comparator 2 output has a logic zero level in case the Wheatstone bridge within the allowed tolerances, and a logical level of 1 in case the weighting of the Wheatstone bridge is greater than the allowed tolerance. The output of the comparator 2 of an unauthorized change in the resistance of the output circuit of the belay device 7 is routed to the logic circuit 3. In order not to indicate a failure of the protected device while the belay device 7 is not in operating mode, i.e. when either the switching circuit 5 In the conductive state or when the switching circuit 5 is in the non-conductive state, but the voltage at the capacitor C has not yet reached its nominal value, further signals are supplied to the logic circuit 3, namely the supply voltage U2 and the control voltage U3. The logical product of said signals provides an indication of an unauthorized change in the resistance of the output circuit of the protection device 7 only in its operating mode.

In logic circuit 3, the signals applied to its three inputs have the following selected logic levels:

- if the Wheatstone bridge weighing is within the permitted tolerances, the logic zero level is at the first input of logic circuit 3; independently variable, xi = O. If the balance is not within the allowed tolerances, the logic one is at the first input; independent variable xi = I.

When the switching circuit 5 is closed and the supply voltage U2 is on capacitor C, the logic 1 level is at the second input of logic circuit 3; independently variable variable X2 = I. With open circuit 5, when there is no supply voltage U2 at capacitor C, the logic zero level is at the second input; independently variable X2 = 0.

- if a fault is indicated by one of the electrical sensors of the physical quantity, the control voltage U3 and the third input of the logic circuit 3 are at logic level 1; independently variable X3 = I. If no fault is indicated, the control voltage U3 and the third input have a logic zero level; independently variable X3 = 0.

The output of logic circuit 3 will then be the logical levels of the dependent variable y according to the truth table:

line

Independent variable XI X2 X3

Dependent variable y

O ^!

O o

O

AND

AND

AND

AND

I o

I o

I o

I o

o o

AND

I o

O

AND

I o

o o

□

I o

o o

It is apparent from row 5 of the truth table that the output of logic circuit 3 will be level 1 only when the Wheatstone bridge is weighed above the allowable tolerances when the electrical protection device is in operating mode, that is, it is ready to perform the protection function in case of failure. The output of the logic circuit 3 is connected to the input of the indicator circuit 4.

In practice, the circuitry of the invention is used in an electrical circuit breaker used in a long-term rotating disk test apparatus. Conditions dangerous to the test equipment and the rotating disc, such as overspeeding, lubricating oil pressure drop, and shutdown of the electrical power supply to the test electronics are protected. When a fault occurs on any of the; from these conditions, the electrical circuit breaker immediately interrupts the test being performed. In the event of a fault in the power member 6 and its electrical connection, the electric breaker device cannot take its protective action. This is when the winding of the power element 6 and / or its electrical connection is interrupted or short-circuited, or if there is an unauthorized change in resistance caused by partial short-circuits or transition resistors. The circuit according to the invention indicates the state of occurrence and, if necessary, it can either visually or acoustically alert the operator or perform another function automatically.

The circuitry of the indication according to the invention can be used wherever a change in operating conditions can lead to a breakdown of the equipment being operated, especially where a very short response time is required, i.e. the time between the moment of failure indication by the electrical physical quantity sensor.

Claims (1)

SUBJECT Circuit wiring Indication of disconnection, short circuit and unauthorized change of resistance of the output circuit of the electric protection device, where in the protective device the output from the DC supply voltage with high internal resistance is connected to the protective device ground through a capacitor. the control input is connected to an output from a logic circuit controlled via an electronic circuit by an electrical sensor of a physical quantity from a fused device, and whose output is connected to the protective device frame through a power element, characterized in that the output of the switching circuit (5) is connected to the first input amplifiers (lj, and on the other hand via INVENTION the first, second and third resistors (R1, R2 and R3) to the frame of the protective device (7j), the output of the stabilized voltage source (U1) is connected to the connector of the first resistor (R1) and the second resistor (R2), a second resistor (R2) and a third resistor (JRQ) are connected to the second input of the amplifier (1), the output of which is connected via a comparator (2) to the first input of the logic circuit, (3). and a third input is connected to the control input of the switching circuit (5), the output of the logic circuit (3) being connected to the input of the indicating circuit (4).