Delixi circuit breaker operation failure

Operation failure is manifested by the dragging or misoperation of the circuit breaker. Because the most basic and important function of the high-voltage circuit breaker is to operate correctly and remove the fault of the power grid quickly. If the circuit breaker drags or malfunctions, it will pose a serious threat to the power grid, first of all: (1)) expand the scale of the impact of the incident, which may expand the original only circuit fault to the entire busbar, or even the whole plant and the whole plant power outage; (2) If the time of fault removal is prolonged, it will affect the operation and stability of the system and aggravate the damage of the controlled equipment; (3) The formation of non-full phase operation. As a result, it often leads to abnormal operation and vibration of power grid maintenance, which simply expands into a system incident or a large-scale power outage. For example. In a power plant, the sleeve SW2-220 type oil-less circuit breaker tie rod was broken due to the lack of strength, and the B phase was not disconnected, forming a non-full-phase operation, so that the neutral point gap of the No. 4 main transformer produced spark discharge, and the arc involved the 220kV eastward bus, which made the bus differential maintenance action, and the No. 2 generator and two lines tripped, and because of the influence of negative sequence current, the main insulation of the generator rotor pole was almost all damaged.

Delixi circuit breaker operation failure

Delixi circuit breaker operation failure

The top causes of operation failure are:

(1) Deficiencies in operating organization;

(2) Mechanical defects of the circuit breaker body;

(3) Defects of operation (control) power supply.

The specific analysis is as follows.

1. Operational organizational shortcomings.

The operating structure includes electromagnetic structure, spring structure and hydraulic structure

The field calculations show that the defects of the operating organization are the primary cause of the operation failure, accounting for about 70%. For electromagnetic and spring tissues, the primary cause of mechanical problems in its tissues is that they are not sensitive. The jamming here may not only be due to the insensitive adjustment of the original assembly, but also due to poor maintenance, and another reason for the formation of tissue mechanical problems is improper lock adjustment, and the self-tripping (tripping) of the operation circuit interrupter is most likely due to such reasons. The loosening and displacement of each joint part is mostly due to the fact that the screws are not tightened, the pins are not well attached or the original anti-loosening structure has shortcomings. It is worth noting that loosening and displacement are far more common than damage to parts, so it can be seen that the meaning of preventing loosening is no less than preventing damage to parts.

For the hydraulic structure, its mechanical defects are mainly formed by poor sealing, so it is particularly important to ensure the reliable sealing of high oil pressure parts.

The electrical shortcomings of the organization are mainly caused by the shortcomings of auxiliary switches and micro switches. Most of the problems of auxiliary switches are not switched, which often causes the operating coil to burn out. In addition, there is also a problem because of the poor contact after switching. Micro switches mainly refer to the interlocking and maintenance switches on hydraulic organizations. The incident calculation data of SW6 breaker show that the micro switch defects account for about 50% of the electrical defects of its tissue. In addition to the shortcomings of auxiliary switches and micro switches, the largest share of the electrical shortcomings of the organization is the secondary circuit fault. Attention should also be paid to these "secondary angles of secondary angles". For example.

(1) In the 220kV substation of a certain power bureau, the SW6-220 circuit breaker C phase of the main transformer secretly jumped during operation, forming non-full-phase operation, resulting in severe consequences. The reason is that the outer sheath of the lead wire of the C-phase organization opening coil is worn, and the iron yoke window is discharged, forming the negative electrode grounding of the DC system. Because the insulation monitoring equipment of the substation failed, it could not be found in time, and the appearance team accidentally touched the positive pole during the operation, forming a DC two-point grounding, so that the circuit breaker C phase jumped secretly.

(2) The SW6-220 type oil-less circuit breaker of a substation is connected to the wrong secondary line during maintenance, so that the circuit breaker refuses to divide when there is a fault, and it expands into a power outage for the whole institute.

(3) The SW6-220I. type oil-less circuit breaker of a power plant, the F4 auxiliary switch of the CY3 organization, due to poor manufacturing quality and lack of contact elasticity, seems to be connected but not connected. When the line fails, the circuit breaker can not be opened correctly, so that the circuit breaker fails maintenance action, 220kV bus power failure, less power transmission 155,000 kW · h, 75,000 kW less power generation, · h。

2. The mechanical shortcomings of the circuit breaker body

The shortcomings of the mechanical failure of the circuit breaker body are all mechanical shortcomings. These include damage to the porcelain bottle, loose joints, damaged parts and jamming of foreign objects. For example; The SW7-220 type oil-less circuit breaker of the No. 3 generator and transformer of a power plant rejects C during grid-connected operation, forming non-full-phase operation, causing the 220kV bus connection and line circuit breaker to trip, and reducing power generation by 400,000 kW ··h. The reason for the incident is that the circuit breaker has been operated 3,600 times, the parts are severely worn, the straightening structure is deformed, and it is not overhauled and replaced in time, which finally caused the incident.

The SW7-220 type oil-less circuit breaker has a special "late action" problem, and the reason is: the oil in the arc extinguishing chamber and the triangle box of the circuit breaker is isolated. In order to prevent the oil leakage of the arc extinguishing chamber into the triangle box during operation, the dynamic seal of the conductive rod is generally adjusted very tightly, when the temperature rises in summer, the dynamic seal often holds the conductive rod, when the circuit breaker receives the opening order, the conductive rod movement to overcome the holding force, often dozens to hundreds of millimeters late to complete the opening action. For this "late moving" phenomenon, it is not easy to find out only by checking the circuit breaker after the incident, and can only be found by looking at the oscilloscope of the faulty recorder. In order to prevent such incidents, in the SW7-220 type less oil circuit breaker maintenance process has been the allowable scale of the conductive rod dialing force has been ruled, as long as the maintenance process is carefully implemented, there will be no "late action" incident in operation.

3. Disadvantages of operation (control) power supply

The shortcomings of the operating power supply of the circuit breaker are also one of the three major root causes of operation failure. Among the disadvantages of operating power supplies, the lack of operating voltage is the most common disadvantage. The reason is mostly because the power station chooses the AC power supply after silicon rectification as the operating power supply, and when the system fails, the power supply voltage drops significantly, or although there is a battery pack, the voltage drop between the operating power supply and the circuit breaker is too large, so that the actual operating voltage is lower than the lower limit of the rule. For example, a substation has a problem due to a distribution line, and the circuit breaker bursts when it coincides; The phase of the 44kV line of the other substation is wrong, and the circuit breaker bursts when the switch is closed and connected to the grid. These are all caused by the power supply of the silicon rectifier supplied by the substation, and when the line is faulty, the bus voltage drops. Therefore, in 1982, the former Ministry of Water Resources and Electric Power formulated the "Interim Rules on the Operation Energy of Substations", requiring that new substations should no longer use silicon rectifier as the operating power supply, and it is recommended to promote the use of batteries and energy storage operating organizations, and to transform and improve the operating power supply of existing substations, and strengthen management.

Delixi circuit breaker operation failure

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