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Safety comes from prevention; danger lies in control, and accidents occur when control is lost. We believe that, apart from irresistible natural disasters, through our efforts, all accidents should be preventable and any potential hazards should be under control. Hazard identification and preventive control 0 Introduction Safe production is the foundation of all activities in power enterprises, and it remains an eternal theme for such companies. Especially under the current extremely severe electricity situation, ensuring safe production to maintain the stable operation of the power grid is of particular importance. After 1998, under the specific guidance of their superior authorities, local bureaus across the country began to implement comprehensive pre-control methods for work safety on a full scale. Through continuous refinement and development in practice, significant results were achieved. This article mainly introduces the background of hazard pre-control, the general concept of hazard pre-control, as well as the characteristics and causes of hazards. It also explains the methods for identifying and controlling hazards in substation operation. The main task of the duty officer is to operate and manage the maintenance of electrical equipment. The challenge lies in the large number of devices that need maintenance, the heavy workload, and the fact that potential hazards affecting safe production exist or lurk at various stages. Therefore, ensuring safety through the preemptive control of hazard points has become an important task. Background of the preemptive control method for hazard points: In the past, to prevent accidents caused by human errors during operations, safety organizational measures and safety technical measures specified in the Ministry of Energy’s \"Power Safety Work Regulations\" were primarily employed. However, in practice it was found that, when formulating these organizational and technical measures, workers were often limited by the experience and knowledge of those who prepared them; as a result, they lacked a comprehensive understanding of the risks associated with the entire operation process. The safety measures devised also often simply copied those outlined in the \"Power Safety Work Regulations\", or were even simpler still. Phrases like \"be careful\" became mere routine reminders, leading to safety measures that were not tailored to specific situations. 2. General concept of pre-control of hazard points Hazard points refer to the working environments that may cause harm during production operations, the machinery and equipment as well as workers who may pose a risk, as well as irregular operations that violate safety regulations and habitual violations. The so-called risk prediction and control method involves analyzing each task in power production based on factors such as the nature of the work, working methods, working environment, personnel conditions, and the actual condition of equipment. It aims to identify potential risk factors that could lead to human error accidents. Based on relevant regulations and procedures, preventive measures are then established, and systematic and standardized operations are carried out at the production site in order to prevent such accidents from occurring. A hazard is a potential cause of accidents; if it is not addressed and prevented, it may develop into an accident under certain conditions. By conducting prior research, analysis, and prediction, as well as taking preventive measures, such hazards can be averted and safety ensured. Hazard prediction and control is precisely such an effective method for proactive prevention. Generally speaking, hazard points arise under the following circumstances: 1. They emerge as a result of operational activities ； 2. Generated as a result of special weather changes ； 3. Generated as a result of defects in equipment manufacturing ； 4. Caused by inadequate inspection and maintenance of the equipment ； 5. *Generated due to habitual violation of procedures. Therefore, hazard points possess four characteristics: objective reality, latency, complexity and variability, and predictability. Three Operations’ > Identification of Hazardous Points in Substation Operations The key to identifying hazardous points is accuracy. The procedure for identifying potential hazards in substation operation is as follows: 1. Comprehensive inspection: This is a fundamental step in the proactive management of substation hazards; it involves physically examining each piece of equipment, identifying potential hazards, recording them, summarizing the findings, and reporting them. This is an important method for establishing a database of such hazards. For example, during a comprehensive safety inspection at a certain control station, on-site inspections revealed many potential hazards that were previously unnoticed, both in terms of the environment and the equipment itself. For instance, in the 35kV switchgear room of a certain 110kV substation, there were no protective barriers between all the switchgear units and the wall-mounted bushings, making it easy to come into contact with live parts ； The ladders on the outdoor structures of all substations throughout the site lack protective cages ； The operation buttons on the GIS 110kV local operation panel of a certain 110kV substation lack protective covers, making it easy to accidentally press or activate them when the \"local/remote\" switch is set to \"local\" ； When a single circuit in the 10kV intermediate cabinets of two 110kV substations is taken out for maintenance, it is inconvenient to perform voltage testing; moreover, since the partitions are made of metal plates, this can lead to dangerous situations such as discharge and grounding during voltage testing. 2. Search during operation: This is an important aspect of proactive risk control in substation operations, and it is divided into three parts: during switchgear operations, during work order execution, and during equipment inspection. ⑴During switching operations, the identification of potential hazards is carried out in accordance with the East China region’s \"Six Requirements and Eight Steps\" principle. Based on the actual conditions of the equipment on site, as well as typical operation procedures for substations and on-site operating regulations, potential hazards are identified and determined through the following steps: checking whether the operations are conducted in compliance with the \"Six Requirements and Eight Steps\" guidelines ； Have protective measures been taken in accordance with safety regulations, and are insulating tools being used correctly? ； Operations that are particularly important and require a specific sequence (such as CT switching, bypass operations) ； Installation and removal of grounding wires ； Protect modified value ； Unlock operations, etc. ⑵During the execution of work orders, identification is achieved by breaking down the workflow involved in executing those work orders and analyzing each step; potential hazards are identified and determined in the following areas: whether there are any instances of *inherent violations during authorization ； Are the safety measures correct and complete? ； Have any safety hazards arisen as a result of changes to safety measures, additional tasks, or an expanded scope of work? ； Was unlocking used without authorization during maintenance? ⑶For equipment acceptance, the main considerations are whether the equipment’s condition has returned to a permissible state, whether the personal safety wires have been removed, whether any temporary wiring connections have been taken out, whether the terminal connections are in normal condition, and whether all safety measures are in place during operation. 3. Identification during routine maintenance and inspections: It serves as a verification and supplement to the proactive control of hazard points. It should be identified and determined based on the characteristics of different substations, taking into account the impact of equipment and the environment on people, as well as the impact of environmental changes on the equipment. Entering an SF6 switch room can result in injury from step voltage in cases of equipment flashover during heavy fog, or from ground fault faults during thunderstorms ； Whether the ground resistance is within acceptable limits, etc. Control of four types of hazard points The key to dealing with hazard points lies in control and rectification; preventive measures are generally taken using the following methods: 1. Implement targeted preventive controls in conjunction with major repairs (upgrades). The annual overhaul (renovation) is a period when substation switching operations and work order executions are most concentrated, making it the busiest time, as well as a critical phase for safe operation. Pre-control for major overhauls (renovations) mainly involves, prior to the start of such overhauls, actively cooperating with the maintenance department to conduct an assessment of the substation, understand the health status of the equipment and any existing problems, and formulate a detailed plan to ensure that \"personnel, tools, and spare parts\" are all properly arranged. Utilize team meetings to discuss the three types of measures, ensuring that the organizational measures, technical measures, and precautions are all clearly defined; focus on studying the tasks that require technical improvements* ； Identify the main hazard points associated with this major repair (modification) under the three measures, and determine how to prevent or eliminate them. During the major overhaul (renovation), each shift shall record in the relevant logbooks the number of grounding wires required each day and their installation locations, so as to ensure that closing the circuit with grounding wires is prevented due to the omission of such wires during the resumption of operation. At the same time, major overhauls (renovations) can also be used to address issues that are difficult to fix on a regular basis. 2. Carry out standardized operations to achieve scientific pre-control. For example, since many dangerous points were identified in the installation of grounding wires during operation, we adopted a two-end positioning method to prevent serious misoperation accidents such as installing grounding wires while the system is under voltage or closing switches while grounding wires are in place. “The “two-end positioning method” means that, based on similar equipment and wiring methods, under the same maintenance mode, the positions of the conductor end and the grounding end of the ground wire must be standardized and fixed. Unified requirements are mainly set out in the following points. (1) For switchgear where it is difficult to install ground wires with long handles, the outer phases should first be grounded using standard handles before proceeding to ground the inner phases. (2) When one side of the knife switch is live and a ground wire is installed on the non-live side, select the conductor end that ensures a safe distance from the body and the live side; preferentially use the conductor end that is farthest away from the live part. (3) It is prohibited to place a ladder at the middle position where one side of the switch is live in order to install or remove the grounding wire; it is also not allowed to hold the porcelain insulator on the side opposite the live switch while installing or removing the grounding wire. (4) The outdoor grounding terminal shall have functions to prevent connecting the grounding wire while it is under voltage and to prevent closing the switch while the grounding wire is connected (a mistake-prevention baffle can be installed). A separate grounding point can be provided at an appropriate location below the main transformer lead bridge, and all grounding points at the same location must be unique. (5) The indoor grounding terminals should all be located outside the switchgear and access doors (during arc suppression maintenance of step-up and step-down transformers), to prevent the entire grounding wire from being inside the switchgear; in special cases where it is necessary to place them inside the switchgear, error prevention mechanisms must be in place ； (6) Where possible, consider a malfunction prevention locking function between the conductor terminal and the grounding terminal; otherwise, it should be placed in a location clearly visible to the operator. (7) For GG-1A type fixed cabinets, grounding for equipment maintenance in the feeder bay: when the busbars are not shut down simultaneously, the busbar circuit breaker anti-misoperation locking pin shall be given priority as the grounding point ； When the busbars are out of service simultaneously, the grounding terminal can be the grounding screw located at the bottom of the switch mechanism. Grounding on the 10 kV side of the main transformer and on overhead outlet lines: The conductor terminal must be connected to the copper or aluminum busbars inside the rear cabinet door, and then passed through that door to be grounded at the dedicated grounding screw located outside the cabinet. Busbar maintenance grounding: The conductor terminal should be located at the copper or aluminum busbar above the corresponding busbar voltage transformer cabinet. If there are two voltage transformers on a bus, the three-phase voltage transformer cabinet located in the middle of that bus can be selected. (8) For middle-mounted cabinets, for grounding the equipment under the outgoing cable bay cabinets: prioritize closing the grounding switch; if grounding wires are required for the work, the construction personnel shall install them themselves. During 10kV bus maintenance: all feeders cabinets are set to line maintenance mode (with the drawers in cold standby status), the capacitor cabinets are set to capacitor maintenance mode, the step-up transformer cabinets and service transformers are set to maintenance mode, while the 10kV switchgear for the main transformer and the 10kV bus disconnect switches are also set to maintenance mode. Ground wires are installed on the power side (such as at the bus disconnects and the main transformer), whereas no ground wires are required on the bus itself. Based on the specific equipment in the substation, we standardized and fixed the locations of the conductor ends and grounding ends that require grounding wires in all 11 substations, and marked them in accordance with the regulations. This work is particularly important for the operation and management of unattended substations under the current centralized control station management approach, as the operators at the centralized control stations have to deal with 11 substations, and they are often not very familiar with the equipment there. By using the grounding wire positioning method, it is ensured that the installation locations of the grounding wires are consistent, which enables operators to have a clear understanding when working with similar equipment ； Secondly, on-site equipment can be fully utilized to connect to the ground wire in order to achieve forced locking, thereby strengthening the management of ground wires through technical measures ； Secondly, it is possible to strengthen the review and supervision function of subsequent operations over previous ones, thereby effectively preventing the failure to remove grounding wires. For example: Use operation package to implement typical operations. During major overhauls of 110 kV and lower voltage substations, a set of operation documents for the overhaul is prepared based on the typical maintenance procedures outlined by the maintenance department, in conjunction with the typical power outage sequences determined by the dispatching department, so as to carry out the standard operations. This model has been in use since 2003; it enhances the safety of switching operations by utilizing operation packages, improves the efficiency of various steps involved in shutting down and restarting equipment, reduces the workload on operators, and boosts the operational skills of those on duty. 3. Learn from the lessons of the accident and implement preventive measures. Carefully study the accident reports, analyze the causes of the accident, take into account the actual conditions of the centralized control station, draw conclusions from this experience, learn from the mistakes made, and put forward targeted preventive measures to prevent similar accidents from occurring again. 4. Make full use of rules and regulations to regulate human behavior. Statistical data show that 82% of accidents are caused by habitual violations of rules. People are the most active and decisive factor among all elements of productivity; therefore, regulating human behavior is key to controlling accidents resulting from human error. By establishing and improving a comprehensive set of safety assurance systems centered on the safety production responsibility system, as well as a motivation mechanism for personnel throughout the entire process, the smooth implementation of the preventive control system can be ensured. V. Conclusion Hazard prediction and control is a form of reverse thinking, which uses the possible consequences to alert workers to potential dangers. Talking about “danger” is more intuitive and concrete than talking about “safety”; it is more targeted and effective, and easier for people to understand and accept. It is more conducive to raising our safety awareness, correcting habitual violations of rules, and enhancing our self-protection capabilities. It is more conducive to putting into practice the principle of \"safety first, prevention first,\" thereby further ensuring that our work in safety production remains under control. This post was last edited by hw197358 on 2009-2-16 13:09.]