KR200344438Y1 - Digital output part circuit of digital protective relay - Google Patents

Abstract

The present invention relates to a digital output circuit of a digital protection relay, and by using two output ports of a CPU, the photocoupler operates normally only when two output ports output a desired signal, There is an effect that can improve the reliability for.

The digital output circuit of the digital protection relay according to the present invention is a signal input unit for stepping down the input voltage by receiving a three-phase power, and a digital signal from the signal input unit, voltage transformer (PT) and current transformer (CT) A digital input unit that receives the received signal and outputs the combined signal, and outputs a signal for determining whether the relay is driven by receiving the output voltage of the signal input unit, and outputs the calculated and combined signal by receiving the signal from the digital input unit. A digital protective relay comprising a calculation and a control unit, wherein a signal output from the first and second output ports of the calculation and control unit is input to a first terminal and a second terminal, and a power supply voltage is input to a fourth terminal. A photo coupler for outputting an output signal through A signal amplifier for amplifying and outputting a signal received from the third terminal of the photocoupler; And a relay for inputting the output signal of the signal amplifier and the power supply voltage to the first and fourth terminals and outputting the output signal to the second and third terminals.

Description

DIGITAL OUTPUT PART CIRCUIT OF DIGITAL PROTECTIVE RELAY}

The present invention relates to a digital output circuit of a digital protection relay, and more particularly, to a digital input circuit of a digital protection relay that prevents the circuit from malfunctioning due to noise of an external environment.

In general, protection relays are devices installed in electric circuits, communication lines, etc., to accurately detect overcurrent, phase loss, phase imbalance, and reverse phase by a set operating time to protect devices or lines more accurately.

In addition, the digital protection relay has a voltage transformer PT and a current transformer CT therein, and detects the voltage and current of the system of the protection range through the two transformers. As protective relays move from inductive or stationary relays to digital relays in the past, protective relays are required to have a wider range of correction and to operate correctly. In particular, digital protection relays must operate correctly by detecting the voltage and current of the system without distortion even at low currents of less than 1A and low voltages of less than 10V to hundreds of A and hundreds of V.

Hereinafter, a digital input circuit of a digital protection relay according to the prior art will be described with reference to the accompanying drawings.

1 is a configuration diagram schematically showing a conventional digital protection relay.

As shown in FIG. 1, the digital protection relay includes a signal input unit 110, an input unit display unit 120, an operation and control unit 130, a digital input unit 140, a digital output unit 150, and a trip coil driver ( 160). Here, reference numeral 200 denotes a load, reference numeral 300 denotes a circuit breaker, reference numeral 310 denotes a trip coil of the circuit breaker, and reference numeral 400 denotes an external connection circuit.

As described above, the digital protective relay receives the input of the relay through the voltage transformer (PT) and the current transformer (CT) and the digital input unit 140 in the electric line, and through the operation and control unit 130, the digital output unit ( 150).

The signal input unit 110 receives a three-phase power source to step down the input voltage, and the input unit display unit 120 functions to display an input voltage input to the signal input unit 110 to the outside.

The digital input unit 140 receives a digital signal from an external (for example, switchboard, etc.), a voltage transformer (PT) and a current transformer (CT), the signal input unit 110, and the like and calculates and combines (for example, , AND or OR) is output to the operation and control unit 130.

The operation and control unit 130 receives the output voltage of the signal input unit 110 and outputs a signal for determining whether to drive the relay, and receives the signal from the digital input unit 140 and outputs the operation and combined signal do.

The digital output unit 150 inputs an output signal of the operation and control unit 130 to output a signal for controlling the operation of the component. For example, the digital output unit 150 may control to sound an alarm by the signal received from the operation and control unit 130.

The trip coil driver 160 generates a signal for controlling the driving of the trip coil 310 of the circuit breaker by inputting the calculation and the output signal of the controller 130.

2 is a circuit diagram of a digital output unit of a digital protection relay according to the prior art.

As shown in FIG. 2, the conventional digital output unit includes a first resistor Nd1 for inputting a power supply voltage VCC and a first resistor connected to the first node Nd1 and the second node Nd2. (R1), a third node (Nd3) connected to the output port (Port1) of the operation and control unit 130, a fourth node (Nd4) for inputting a power supply voltage (+ 24V), and the fourth node ( A second resistor R2 connected between Nd4 and node Nd5, a first terminal is connected to the second node Nd2, and a second terminal is connected to the third node Nd3, and the fifth A photocoupler 152 having a fourth terminal connected to the node Nd5 and a third terminal connected to the sixth node Nd6, an input terminal connected to the sixth node Nd6, and an output terminal connected to the node Nd7. A signal amplifier 154 connected thereto, an eighth node Nd8 for inputting a power supply voltage (+ 24V), a diode D1 connected between the seventh node Nd7, and the eighth node Nd8; , The seventh node (Nd7) is the first terminal A relay 156 connected to the eighth node Nd8 to a fourth terminal, a second terminal to a ninth node Nd9, and a third terminal to a tenth node Nd10; And a varistor TNR connected between the node Nd9 and the tenth node Nd10.

As shown in FIG. 2, the digital output unit of the conventional digital protection relay receives input signals such as a current transformer CT, a voltage transformer PT, and the digital signal input unit by the calculation and control unit 130. When the output signal is sent to the digital output unit 150, when the output port Port1 connected to the third node Nd3 is converted from 'high' to 'low', the first node ( The power supply voltage VCC applied to Nd1 is applied to the first and second terminals of the photocoupler 152 through the first resistor R1. Accordingly, the photocoupler 152 is turned on and outputs a power supply voltage (+ 24V) input to the fourth node Nd4 to the sixth node Nd6. At this time, the sixth node Nd6 has a 'high' signal.

When the 'high' signal is input through the sixth node Nd6, the signal amplifier 154 amplifies and outputs a voltage and a current capable of driving the relay 156. As a result, the relay 156 outputs a signal amplified to the second and third terminals 2 and 3 by the power input to the first and fourth terminals 1 and 4. Therefore, the digital output unit 150 operates in conjunction with the external wiring circuit 400.

However, in the digital output circuit of the conventional digital protection relay having the above configuration, when noise is applied to the outside, the output port Port1 of the operation and control unit 130 is changed from the 'high' state to the 'low' state. The photocoupler 152 is turned on to drive the relay 156. For this reason, the digital output circuit has a problem of malfunctioning in connection with the external wiring circuit 400.

In order to solve this problem, the digital output circuit of the conventional digital protection relay is 'high' when the 'high' signal applied to the output port Port1 of the operation and control unit 130 maintains its state for a long time. Although the circuit can be configured to recognize as a signal, there is a problem that the signal is delayed in this case.

Therefore, the present invention was made to solve the above problems, and an object of the present invention is to operate the photocoupler only when two output ports output a desired signal by using two output ports of the CPU. The present invention provides a digital output circuit of a digital protection relay with improved reliability for noise.

1 is a schematic view showing a conventional digital protection relay

2 is a circuit diagram of a digital output unit of a digital protection relay according to the prior art.

3 is a circuit diagram of a digital output unit of a digital protection relay according to the present invention.

<Description of Symbols for Main Parts of Drawings>

152: photo coupler 154: signal amplifier

156: relay

The digital output circuit of the digital protection relay according to the present invention for achieving the above object,

A signal input unit for receiving a three-phase power supply and stepping down an input voltage; a digital input unit for receiving a digital signal from the signal input unit, a voltage transformer (PT), and a current transformer (CT) and outputting a calculated and combined signal; In the digital protection relay comprising an operation and control unit for receiving a signal from the input unit to determine whether the relay is driven, the operation and control unit for receiving a signal from the digital input unit and outputs a calculated and combined signal,

A photocoupler configured to input signals output from the first and second output ports of the operation and control unit to first and second terminals, input a power supply voltage to a fourth terminal, and output an output signal to a third terminal;

A signal amplifier for amplifying and outputting a signal received from the third terminal of the photocoupler; And

And a relay for inputting the output signal of the signal amplifier and the power supply voltage to the first and fourth terminals and outputting the output signal to the second and third terminals.

The digital output circuit includes: a first resistor connected between the first terminal of the operation and control unit and the first terminal of the photocoupler; A second resistor connected between the node for inputting the power supply voltage and a fourth terminal of the photocoupler; A diode connected between the first terminal and the fourth terminal of the relay; And a varistor connected between the second terminal and the third terminal of the relay.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention.

3 is a circuit diagram of a digital output unit of a digital protection relay according to the present invention.

As shown in FIG. 3, the digital output circuit includes a first node Nd1 connected to a first output port Port1 of the operation and control unit 130 of FIG. 1, and the first node Nd1. And a first resistor R1 connected to the second node Nd2, a third node Nd3 connected to the second output port Port2 of the operation and control unit 130, and a power supply voltage (+ 24V). A first terminal is connected to an input fourth node Nd4, a second resistor R2 connected between the fourth node Nd4, and a node Nd5, and a first terminal is connected to the second node Nd2. A photocoupler 152 having a second terminal connected to a third node Nd3, a fourth terminal connected to the fifth node Nd5, and a third terminal connected to a sixth node Nd6, and the sixth node ( A signal amplifier 154 having an input terminal connected to Nd6 and an output terminal connected to node Nd7, an eighth node Nd8 for inputting a power supply voltage (+ 24V), the seventh node Nd7, and the Connected between the eighth node Nd8 The diode D1 and the seventh node Nd7 are connected to a first terminal, the eighth node Nd8 is connected to a fourth terminal, and the second terminal is connected to a ninth node Nd9 and a third terminal. Is configured to include a relay 156 connected to the tenth node Nd10, and a varistor TNR connected between the ninth node Nd9 and the tenth node Nd10.

As shown in FIG. 3, the digital output unit of the digital protection relay receives the input signals of the current transformer CT, the voltage transformer PT, and the digital signal input unit, and receives the digital signals by the operation and control unit 130. When sending an output signal to the output unit 150, the first output port Port1 connected to the first node Nd1 is converted from 'high' to 'low' and the second node Nd2 When the second output port (Port2) connected to is converted from 'low' to 'high', the 'high' signal is the first of the first resistor R1 and the photocoupler 152. And the photo coupler 152 is turned on by being applied to the second terminals 1 and 2. Accordingly, the sixth node Nd6, to which the output signal of the photocoupler 152 is output, becomes 'high', and the signal amplifier 154 amplifies a voltage and a current capable of driving the relay 156. To the seventh node Nd7. As a result, the second and third terminals 2 and 3 of the relay 156 are driven to operate the digital output unit 150 in connection with an external wiring circuit.

If noise is applied from the outside to cause a malfunction in which both the first and second terminals 1 and 2 of the photocoupler 152 are 'high', all of the input portions of the photocoupler 152 are ' Since the high 'is applied, the photocoupler 152 is not turned on, so no malfunction occurs. In addition, when a malfunction occurs in both the first and second terminals 1 and 2 of the photocoupler 152 with a low, the input coupler of the photocoupler 152 is applied with a low so that the photocoupler is applied. It is impossible to turn on, so no malfunction occurs.

Preferred embodiments of the present invention as described above are disclosed for the purpose of illustration, those skilled in the art will be possible to various modifications, changes, additions, etc. within the spirit and scope of the present invention, such modifications and modifications are the following utility model registration claims Should be seen as belonging to.

As described above, according to the digital output circuit of the digital protection relay according to the present invention, the photocoupler is used only when the two output ports output the desired signals using the two output ports of the CPU. By making it operate normally, the reliability with respect to noise is improved.

Claims (2)

A signal input unit for receiving a three-phase power supply and stepping down an input voltage; a digital input unit for receiving a digital signal from the signal input unit, a voltage transformer (PT), and a current transformer (CT) and outputting a calculated and combined signal; In the digital protection relay comprising an operation and control unit for receiving a signal from the input unit to determine whether the relay is driven, the operation and control unit for receiving a signal from the digital input unit and outputs a calculated and combined signal, A photocoupler configured to input signals output from the first and second output ports of the operation and control unit to first and second terminals, input a power supply voltage to a fourth terminal, and output an output signal to a third terminal; A signal amplifier for amplifying and outputting a signal received from the third terminal of the photocoupler; And And a relay for inputting the output signal of the signal amplifier and the power supply voltage to the first and fourth terminals and outputting the output signal to the second and third terminals. The digital output circuit of claim 1, A first resistor connected between the first terminal of the operation and control unit and the first terminal of the photocoupler; A second resistor connected between the node for inputting the power supply voltage and a fourth terminal of the photocoupler; A diode connected between the first terminal and the fourth terminal of the relay; And And a varistor connected between the second terminal and the third terminal of the relay.