CN118199003A - Circuit breaker tripping circuit and fault monitoring circuit thereof - Google Patents

Abstract

The present invention relates to a circuit breaker tripping circuit and a fault monitoring circuit thereof, and belongs to the technical field of circuit breaker protection control. The circuit includes a main circuit and an auxiliary circuit, wherein the main circuit includes a first detection branch and a second detection branch both provided with detection elements, and the detection element is used to act when it detects that current flows in the branch; one end of the first detection branch is used to connect the power supply of the tripping circuit, and the other end is connected to one end of the second detection branch and the connection point is used to connect the connection point between the tripping contact in the tripping circuit and the circuit breaker position auxiliary contact, and the other end of the second detection branch is used to connect the circuit breaker opening position detection contact; the auxiliary circuit includes a logic processing unit, and the input end of the logic processing unit is connected to the action signal generated by the detection element, which is used to judge the tripping circuit fault when no action signal is received. The tripping circuit includes the above-mentioned fault monitoring circuit. The present invention meets the tripping circuit fault monitoring requirements under all states of the circuit breaker.

Description

A circuit breaker tripping circuit and fault monitoring circuit thereof

Technical Field

The invention belongs to the technical field of circuit breaker protection control, and in particular relates to a circuit breaker tripping circuit and a fault monitoring circuit thereof.

Background technique

For a circuit breaker, its tripping circuit is generally used to energize the closing coil and realize the opening of the circuit breaker when receiving a tripping command, so as to isolate the power grid fault in time and ensure the safe operation of the power grid. Therefore, the tripping circuit plays an important role in the reliability of the circuit breaker operation. If the tripping circuit of the circuit breaker fails, the power grid fault cannot be isolated in time, which may cause the fault point to be tripped, resulting in large-scale power loss and huge losses. Therefore, it is very necessary to provide a fault monitoring circuit for the tripping circuit of the circuit breaker.

The prior art relates to a trip circuit monitoring circuit, as shown in FIG1 . Among them, the trip output relay normally open contact 1-1, the circuit breaker position auxiliary contact 52a and the trip coil TC are connected in series to form a trip circuit, and a circuit breaker opening position detection contact 52b is provided which is linked with the circuit breaker position auxiliary contact 52a. The contacts 52a and 52b are linked and interlocked. The circuit breaker opening position detection contact 52b is arranged in series in the circuit breaker position monitoring circuit (the circuit where the current detection element BI1 is located) to indicate the circuit breaker opening position state. When a trip command is received, the trip output relay normally open contact 1-1 is controlled to close, so that the trip coil TC is energized, thereby controlling the circuit breaker to open. When the circuit breaker is in the open state, the circuit breaker position auxiliary contact 52a is disconnected, and the contact 52b is closed at the same time. At this time, the monitoring circuit is turned on, thereby indicating that the circuit breaker is in the open state. In the open state, when the trip coil fails or the auxiliary contact of the circuit breaker position fails, the monitoring circuit where the current detection element BI1 is located cannot be turned on. At this time, a trip circuit fault alarm is issued and the closing operation is locked to prevent the line fault from occurring when the circuit breaker is closed and the trip protection cannot be performed, resulting in the expansion of the line fault (tripping of the circuit breaker at the upper level).

Although the above-mentioned prior art can monitor the trip circuit fault information of the circuit breaker in the open state, it cannot monitor the trip circuit fault in the circuit breaker closed state. Moreover, when monitoring the trip circuit fault of the circuit breaker in the open state, it is necessary to know the opening and closing state of the circuit breaker in advance to determine whether the circuit breaker trip coil is faulty. This cannot meet the needs of monitoring the trip circuit fault in all states of the circuit breaker.

Summary of the invention

The purpose of the present invention is to provide a circuit breaker tripping circuit and a fault monitoring circuit thereof, so as to solve the problem that the existing tripping circuit fault monitoring circuit cannot meet the tripping circuit fault monitoring requirements under all states of the circuit breaker.

In order to solve the above technical problems, the present invention provides a fault monitoring circuit for a circuit breaker tripping circuit, comprising a main circuit and an auxiliary circuit, wherein the main circuit comprises a first detection branch and a second detection branch, wherein the first detection branch and the second detection branch are respectively provided with detection elements, and the detection elements are used to act when current is detected to flow in the branches; one end of the first detection branch is used to connect the power supply of the tripping circuit, and the other end is connected to one end of the second detection branch and the connection point is used to connect to the connection point between the tripping contact and the circuit breaker position auxiliary contact in the tripping circuit, and the other end of the second detection branch is used to connect the circuit breaker opening position detection contact linked to the circuit breaker position auxiliary contact; the auxiliary circuit comprises a logic processing unit, and the input end of the logic processing unit is connected to the action signal generated by the detection element, and is used to judge the tripping circuit fault when no action signal is received.

Furthermore, the main circuit also includes a diode, the positive electrode of the diode is connected to the connection point between the first detection branch and the second detection branch, and the negative electrode of the diode is used to connect the connection point between the tripping contact in the tripping circuit and the circuit breaker position auxiliary contact.

Furthermore, the logic processing unit includes a logic or element and a delay function module, the input end of the logic or element is respectively connected to the action signal generated by the detection element, the output end of the logic or element is connected to the output end of the delay function module, and the delay function module is used to output the fault monitoring result after a delay set time.

Furthermore, the logic processing unit is a CPU unit capable of realizing logic processing and delay functions.

Furthermore, the auxiliary circuit also includes an alarm indication unit for giving an alarm when a trip circuit fails, and the alarm indication unit is connected to the output end of the logic processing unit.

Furthermore, the auxiliary circuit also includes a locking closing operation control unit for locking the closing operation when a tripping circuit fails, and the locking closing operation control unit is connected to the output end of the logic processing unit.

Furthermore, a power isolation unit is provided between the logic processing unit and the alarm indication circuit.

Furthermore, the detection element is a current detection element.

Furthermore, the fault monitoring circuit also includes an opening and closing position monitoring unit, and the input end of the opening and closing position monitoring unit is connected to the action signal generated by the detection element, which is used to judge that the circuit breaker is in the closed state when the detection element in the first detection branch is actuated and the detection element in the second detection branch is not actuated, and when the detection elements in the first detection branch and the second detection branch are both actuated, it is judged that the circuit breaker is in the open state.

The beneficial effect of the fault monitoring circuit of the present invention is that the fault monitoring circuit of the present invention determines that the trip circuit has a fault as long as the detection element has no action signal, whether the circuit breaker is in the open state or the closed state. Therefore, the present invention can determine whether the trip circuit has a fault in both the closed state and the open state, meeting the trip circuit fault monitoring requirements in all states of the circuit breaker. Moreover, the fault judgment process does not require the current switch position state of the circuit breaker to be known in advance, so it does not rely on the circuit breaker position monitoring circuit, so the fault monitoring circuit has strong versatility.

The circuit breaker tripping circuit with fault monitoring function provided by the present invention to solve the above technical problems includes a tripping contact, a circuit breaker position auxiliary contact and a tripping coil connected in series in sequence, and also includes a circuit breaker opening position detection contact linked with the circuit breaker position auxiliary contact, the circuit breaker position auxiliary contact and the circuit breaker opening position detection contact are both connected to one end of the tripping coil, the tripping circuit also includes the fault monitoring circuit of the circuit breaker tripping circuit described above, one end of the second detection branch of the fault monitoring circuit is connected to an end of the circuit breaker opening position detection contact that is not connected to the tripping coil, and the connection point of the first detection branch and the second detection branch is connected to the connection point between the tripping contact and the circuit breaker position auxiliary contact in the tripping circuit.

The beneficial effect of the circuit breaker tripping circuit of the present invention is that the tripping circuit of the present invention is provided with a fault monitoring circuit, and when the circuit breaker is in an open state or a closed state, it can judge whether it has a fault, thereby meeting the tripping circuit fault monitoring requirements in all states of the circuit breaker. Moreover, the fault judgment process does not require the current switch position state of the circuit breaker to be known in advance, so it does not rely on the circuit breaker position monitoring circuit, and has strong versatility.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an existing circuit breaker trip circuit fault monitoring circuit;

FIG2 is a circuit breaker trip circuit fault monitoring circuit in an open state according to an embodiment of the present invention;

3 is a circuit breaker trip circuit fault monitoring circuit in a closed state according to an embodiment of the present invention;

In Figures 2 and 3, 1-1 is the tripping contact, 1-2 is the diode D1, 1-3 is the circuit breaker auxiliary contact, 1-4 is the circuit breaker position detection contact, 1-5 is the tripping coil TC, 1-6 is the current detection element BI1, 1-7 is the current detection element BI2, 2-1 is the current detection element BI1 output signal, 2-2 is the current detection element BI2 output signal, 2-3 is the logic OR element, 2-4 is the delay function module, and 3-1 is the power isolation unit.

Detailed ways

The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

The basic idea of the present invention is to improve the hardware of the existing monitoring circuit (FIG. 1), and combine the integrated circuit or microprocessing unit that realizes the processing logic and delay processing to provide a universal monitoring circuit that realizes the full-state fault monitoring of the tripping circuit.

Based on the above basic idea, the fault monitoring circuit of the circuit breaker tripping circuit of this embodiment includes a main circuit and an auxiliary circuit, the main circuit includes a first detection branch and a second detection branch, the first detection branch and the second detection branch are respectively provided with detection elements, and the detection elements are used to act when current is detected to flow in the branch; one end of the first detection branch is used to connect the power supply of the tripping circuit, and the other end is connected to one end of the second detection branch and the connection point is used to connect to the connection point between the tripping contact and the circuit breaker position auxiliary contact in the tripping circuit, and the other end of the second detection branch is used to connect the circuit breaker opening position detection contact linked with the circuit breaker position auxiliary contact. The auxiliary circuit includes a logic processing unit, the input end of the logic processing unit is connected to the action signal generated by the two detection elements, and is used to judge the tripping circuit fault when no action signal is received.

Furthermore, in order to effectively protect the circuit from heating when the power directly flows through the detection element in the second detection branch when the tripping contact is closed, a diode D1 is added to the main circuit of the present embodiment, and the positive electrode of the diode D1 is connected to the connection point between the first detection branch and the second detection branch, and the negative electrode of the diode D1 is used to connect the connection point between the tripping contact and the circuit breaker position auxiliary contact in the tripping circuit.

The logic processing unit of this embodiment can use integrated circuits to construct logic processing and delay function modules, specifically setting up logic or elements and delay function modules, the input end of the logic or element is respectively connected to the action signal generated by the detection element in the first detection branch and the second detection branch, the output end of the logic or element is connected to the output end of the delay function module, and the delay function module is used to output the fault monitoring result after the delay setting time. The setting time here is usually 600ms. As another implementation method, the logic processing unit can also use the CPU unit to use software to implement logic processing and delay functions.

Furthermore, the auxiliary circuit also includes an alarm indication unit for giving an alarm when a trip circuit fails, and the alarm indication unit is connected to the output end of the logic processing unit.

Furthermore, the auxiliary circuit also includes a locking closing operation control unit for locking the closing operation when a tripping circuit fails, and the locking closing operation control unit is connected to the output end of the logic processing unit.

Furthermore, a power isolation unit is provided between the logic processing unit and the alarm indication circuit.

Furthermore, the detection element adopts a current detection element.

Furthermore, the fault monitoring circuit also includes an opening and closing position monitoring unit, the input end of which is connected to the action signal generated by the detection element, and is used to determine that the circuit breaker is in a closed state when the detection element in the first detection branch is actuated and the detection element in the second detection branch is not actuated, and to determine that the circuit breaker is in an open state when the detection elements in the first detection branch and the second detection branch are both actuated. In this way, the monitoring circuit of this embodiment not only realizes the fault state monitoring of the tripping circuit, but also monitors the opening and closing position state of the circuit breaker.

As a preferred implementation, the monitoring circuit of this embodiment may be integrated and mounted on a printed circuit board (PCB).

As a preferred implementation, the monitoring circuit of this embodiment can be designed as an integrated whole with the relay protection device driving the circuit breaker. As another implementation, it can also be designed as an independent module.

This embodiment is a monitoring circuit for a protection device driving a tripping circuit. When multiple devices drive a circuit breaker in parallel, multiple pairs of position auxiliary contacts of the circuit breaker can be used to design a multi-path tripping circuit monitoring circuit. However, all the multiple detection elements are connected to the tripping coil of the circuit breaker. It is necessary to match the loop current to prevent the circuit breaker coil from heating up and to prevent the circuit breaker from tripping due to excessive monitoring loop current (the circuit breaker operating current is generally between 0.25A and 2A, and the monitoring loop must be guaranteed to be within 10mA).

The technical solution of the present invention is further illustrated below by taking a specific tripping circuit.

As shown in FIG2 , a tripping circuit of a circuit breaker includes a tripping contact 1-1, a circuit breaker position auxiliary contact 52a (1-3 element) and a tripping coil TC (1-5 element) which are sequentially arranged in series between the positive and negative poles of a power source. The monitoring circuit of this embodiment includes a main circuit and an auxiliary circuit, wherein the main circuit includes a circuit breaker opening position detection contact 52b (1-4 element) which is linked and interlocked with the circuit breaker position auxiliary contact 52a, a current detection element BI1 (1-6 element), a current detection element BI2 (1-7 element) and a diode D1 (1-2 element), wherein one end of the current detection element BI1 is connected to the positive pole of the power source, and the other end is connected to one end of the current detection element BI2, and the other end of the current detection element BI2 is connected to one end of the contact 52b, and the other end of the contact 52b is connected to the connection line between the circuit breaker position auxiliary contact 52a and the tripping coil TC. The positive electrode of the diode D1 is connected to the connection line between the current detection element BI1 and the current detection element BI2, and the negative electrode of the diode D1 is connected to the connection line between the trip contact 1-1 and the circuit breaker position auxiliary contact 52a. In this embodiment, in order to set the action current in coordination with the current detection element BI1, the internal resistance of the current detection element BI2 is set to be relatively small, so the diode D1 is added to effectively protect the trip contact 1-1 element from being closed, and the power directly flows through the current detection element BI2 to cause the circuit to heat up.

The auxiliary circuit includes a logic processing unit, a power isolation unit, an alarm indication unit and a locking and closing operation control unit. The logic processing unit includes a logic or element and a delay function module. The input end of the logic or element is connected to the action output signal of the current detection element BI1 and the current detection element BI2, the output end of the logic processing unit is connected to the power isolation unit, and the output end of the power isolation unit is respectively connected to the alarm indication unit and the locking and closing operation control unit.

The working principle of the above monitoring circuit is:

1) When the circuit breaker is in the open state, as shown in Figure 2, the circuit breaker position auxiliary contact 52a (1-3 element) is in the open state, and the contact 52b (1-4 element) is in the closed state; at this time, the current signal flows as follows: positive pole of power supply → current detection element BI1 → current detection element BI2 → auxiliary contact 52b → tripping coil TC → negative pole of power supply. When the tripping circuit has no fault, both the current detection element BI1 and the current detection element BI2 are stimulated to act. At this time, the logic processing unit of the auxiliary circuit determines that both the current detection element BI1 and the current detection element BI2 are in action, indicating that the circuit breaker tripping circuit has no fault, and no alarm signal is issued and the closing operation is not locked. When any one of the auxiliary contact and the tripping coil TC fails, the above-mentioned current loop will not be conducted, and the current detection element BI1 and the current detection element BI2 cannot be energized to operate. At this time, the logic processing unit of the auxiliary circuit determines that the current detection element BI1 and the current detection element BI2 are not operating, indicating that the circuit breaker tripping circuit is faulty. The alarm indication unit sends an alarm signal and the locking closing operation control unit locks the closing operation.

2) When the circuit breaker is in the closed state, as shown in FIG3 , the circuit breaker position auxiliary contact 52a (1-3 element) is in the closed state, and the contact 52b (1-4 element) is in the open state; at this time, the current signal flows as follows: positive pole of power supply → current detection element BI1 → diode D1 → auxiliary contact 52a → tripping coil TC → negative pole of power supply. When the tripping circuit is not faulty, the current detection element BI1 is in the energized state, and the current detection BI2 (1-7 element) is in the non-triggered state. At this time, the logic processing unit of the auxiliary circuit determines that there is an action signal, indicating that the circuit breaker tripping circuit is not faulty, and no alarm signal is issued and the closing operation is not locked. When any one of the auxiliary contact and the tripping coil TC is faulty, the above current circuit will not be turned on, and the current detection element BI1 and the current detection element BI2 cannot be excited to act. At this time, the logic processing unit of the auxiliary circuit determines that there is no action signal, indicating that the circuit breaker tripping circuit is faulty, and the alarm indication unit issues an alarm signal and the locking closing operation control unit locks the closing operation.

3) During the process of the circuit breaker tripping, the auxiliary contact 52a of the circuit breaker position in the tripping circuit is in a closed state before the tripping. When the tripping is executed, the tripping contact 1-1 is controlled to close. The tripping contact 1-1 is usually closed for a set time (usually 200ms) and then automatically released (automatically disconnected), and the tripping holding current is realized inside the circuit breaker. Then, during the closing of the tripping contact 1-1, the current detection element BI1 will be bypassed. At this time, the current signal flows from: the positive pole of the power supply → the normally open contact 1-1 of the tripping output relay → the auxiliary contact 52a → the tripping coil TC → the negative pole of the power supply. At this time, regardless of whether the auxiliary contact 52a and the tripping coil TC are faulty, the current detection elements BI1 and BI2 are in a non-triggered state, which belongs to a normal working state. In order to avoid outputting the tripping monitoring signal of the tripping circuit fault in this case, a delay function module is set in the logic processing unit of the auxiliary circuit to avoid false alarms. Considering the duration of this situation, the delay time is generally set to 600ms.

4) Since the auxiliary contacts 52a and 52b of the circuit breaker are interlocked, there are discrete action characteristics in the process of the interlocking contact state change, that is, it takes a certain conversion time for the auxiliary contacts 52a and 52b to reach the final state, and there is a state in which the two contacts are disconnected at the same time during this conversion process. During the period when the two contacts are disconnected at the same time, the current detection elements BI1 and BI2 are both in a non-triggered state, and the time is usually in the millisecond level. This state belongs to the normal working state. In order to avoid outputting the trip monitoring signal of the trip circuit failure in this case, a delay function module is set in the logic processing unit of the auxiliary circuit to avoid false alarms. Considering the duration of this situation, the delay time is generally set to 600ms.

It can be seen that according to the main circuit and auxiliary circuit settings of the monitoring circuit in this embodiment, full-state monitoring of the tripping circuit can be achieved, and when a change in the state of the tripping circuit is monitored (fault), logical processing and alarm indication are performed, and a locking closing operation is performed to avoid the circuit breaker being closed on a transmission line fault and unable to trip the circuit breaker.

The output signals of the current detection element BI1 and the current detection element BI2 are transmitted to the circuit breaker opening and closing state indication module, and the opening and closing state of the circuit breaker is judged according to the states of the current detection element BI1 and the current detection element BI2. Specifically, when the current detection element BI1 has an action signal and the current detection element BI2 has no action signal, it indicates that the circuit breaker is in the closed position state at this time; when both the current detection elements BI1 and BI2 have action signals, it indicates that the circuit breaker is in the open position state at this time.

A circuit breaker tripping circuit embodiment with fault monitoring function

The tripping circuit of this embodiment includes a tripping contact, a circuit breaker position auxiliary contact and a tripping coil connected in series in sequence, and also includes a circuit breaker opening position detection contact linked to the circuit breaker position auxiliary contact, the circuit breaker position auxiliary contact and the circuit breaker opening position detection contact are both connected to one end of the tripping coil, and the tripping circuit also includes a fault monitoring circuit, one end of the second detection branch of the fault monitoring circuit is connected to the end of the circuit breaker opening position detection contact that is not connected to the tripping coil, and the connection point between the first detection branch and the second detection branch is connected to the connection point between the tripping contact and the circuit breaker position auxiliary contact in the tripping circuit. The fault monitoring circuit of this embodiment adopts the fault monitoring circuit in the above embodiment, and the specific structure and working principle of the fault monitoring circuit refer to the above fault monitoring circuit embodiment, which will not be described in detail here.

Claims (10)

1. The fault monitoring circuit of the tripping circuit of the circuit breaker is characterized by comprising a main circuit and an auxiliary circuit, wherein the main circuit comprises a first detection branch and a second detection branch, detection elements are respectively arranged in the first detection branch and the second detection branch, and the detection elements are used for acting when detecting that current flows in the branch; one end of the first detection branch is used for connecting a power supply of the tripping circuit, the other end of the first detection branch is connected with one end of the second detection branch, the connecting point is used for connecting a connecting point between a tripping contact and an auxiliary contact at the position of the breaker in the tripping circuit, and the other end of the second detection branch is used for connecting a detection contact at the breaking position of the breaker, which is linked with the auxiliary contact at the position of the breaker; the auxiliary circuit comprises a logic processing unit, wherein the input end of the logic processing unit is connected with the action signal generated by the detection element and is used for judging the tripping loop fault when no action signal is received.

2. The fault monitoring circuit of a circuit breaker trip circuit according to claim 1, wherein the main circuit further comprises a diode, an anode of the diode being connected to a connection point between the first detection branch and the second detection branch, a cathode of the diode being used to connect a connection point between a trip contact in the trip circuit and a breaker position auxiliary contact.

3. The fault monitoring circuit of a circuit breaker trip circuit according to claim 1, wherein the logic processing unit comprises a logic or element and a delay function module, wherein the input end of the logic or element is respectively connected with the action signal generated by the detection element, the output end of the logic or element is connected with the output end of the delay function module, and the delay function module is used for outputting a fault monitoring result after delaying for a set time.

4. The circuit of claim 1, wherein the logic processing unit is a CPU unit capable of implementing logic processing and delay functions.

5. The circuit of claim 1, wherein the auxiliary circuit further comprises an alarm indication unit for alerting in the event of a trip circuit failure, the alarm indication unit being coupled to an output of the logic processing unit.

6. The circuit of claim 5, wherein the auxiliary circuit further comprises a closing operation control unit for closing a closing operation in the event of a trip circuit fault, the closing operation control unit being coupled to an output of the logic processing unit.

7. The circuit of claim 5, wherein a power isolation unit is disposed between the logic processing unit and the alarm indication circuit.

8. The fault monitoring circuit of a circuit breaker trip circuit according to any one of claims 1 to 7 wherein the sensing element is a current sensing element.

9. The fault monitoring circuit of a circuit interrupter trip circuit according to claim 8, further comprising a switch-on/off position monitoring unit, wherein an input of the switch-on/off position monitoring unit is connected to an operation signal generated by the detecting element, for determining that the circuit interrupter is in a switch-on state when the detecting element in the first detecting branch is operated and the detecting element in the second detecting branch is not operated, and for determining that the circuit interrupter is in a switch-off state when the detecting elements in both the first detecting branch and the second detecting branch are operated.

10. A circuit breaker tripping circuit with fault monitoring function, the tripping circuit comprises a tripping contact, a circuit breaker position auxiliary contact and a tripping coil which are sequentially connected in series, and further comprises a circuit breaker opening position detection contact which is linked with the circuit breaker position auxiliary contact, wherein the circuit breaker position auxiliary contact and the circuit breaker opening position detection contact are both connected with one end of the tripping coil, and the circuit breaker tripping circuit is characterized by further comprising the fault monitoring circuit of the circuit breaker tripping circuit according to any one of claims 1-9, one end of a second detection branch of the fault monitoring circuit is connected with one end of the circuit breaker opening position detection contact which is not connected with the tripping coil, and a connecting point between the tripping contact and the circuit breaker position auxiliary contact in the tripping circuit is connected with a connecting point between the first detection branch and the second detection branch.