A number of safety issues are emerging from archives relating to industry and power plant safety. According to IndustriALL, a global union of workers, 30 industrial accidents occurred in India during May-June 2020, killing at least 75 workers. From 2014 to 2017, 8,004 such incidents occurred in Indian workplaces, killing 6,368 employees. Most mishaps occurred while operating machinery, followed by general industrial accidents.
The power sector has also seen some severe industrial accidents in the recent past. In July 2020, the Neyveli thermal power plant (TPP) in Tamil Nadu suffered a boiler blast, resulting in the death of 14 workers who were engaged in a routine maintenance operation. Thermal power station II (TPS-II) was under shutdown and maintenance activities were being carried out, but a fire broke out in the boiler area following an explosion, resulting in injuries to NLC India Limited’s maintenance team. In August 2020, a major fire accident at the Srisailam left bank hydroelectric power station resulted in a loss of lives in Telangana. These incidents have brought the spotlight back on industrial and power plant safety. Also, safety assumes greater significance in light of the Covid-19 pandemic, as ensuring uninterrupted power supply is a very challenging task. Therefore, appropriate strategies should be planned to make sure that operations and infrastructure are properly supported to provide reliable electricity in any emergency.
Policy guidelines
For power utilities, the Central Electricity Authority (CEA) regulations on (Safety Requirement for Construction, Operation and Maintenance of Electrical Plants and Electric Lines) have been formulated to avert or minimise damages that may be caused by any disaster.
Also, the CEA issued an advisory to all TPPs in the country in January 2019. The key recommendations to be followed by power utilities as per the advisory are: all systems and facilities including control and instrumentation (C&I), control loops, wall soot blowers and long retraceable soot blowers should be completed before the commissioning of the unit/plant; ash handling capacity of the bottom ash handling system, economiser ash handling system, air preheater ash handling system and electrostatic precipitator for fly ash handling system should be designed, keeping in view the likely maximum ash content of coal; water injection for dislodging ash build-up over the furnace bottom should be avoided; standard operating procedures/local management instructions of the plant should be periodically reviewed; the plant’s operating guidelines should be in line with the original equipment manufacturers’ recommendations; the permit system of undertaking operations and maintenance (O&M) activities should be endorsed by the safety department, in addition to the O&M department; and no maintenance work should be undertaken when the boiler is in operation. Besides, proper communication regarding maintenance work should be made to avoid any risky operations; persons working in the ash handling area should be provided with thermal wear, which can withstand high temperatures; plant engineers deployed at different levels should have adequate and relevant experience; the control room logbooks should be filled in a proper manner, indicating the prevailing status of key unit parameters, operating parameters of major equipment/systems and shift activities in a chronological order.
Recently, the CEA has also unveiled the Disaster Management Plan for Power Sector, providing a framework and direction to utilities in the power sector for all phases of the disaster management cycle (that is, mitigation, preparedness, response and recovery). It is intended to guide all agencies within the sector with a general concept of potential emergency and roles and assignments before, during and following emergency situations.
Mitigation strategies
Enhancing plant safety saves money for the utility by reducing medical expenditure and workers’ compensation insurance costs, and adds value to its business by improving work efficiency and productivity.
The key requirements for successful plant management are identifying the centre of the entire plant safety management, ensuring appropriate and timely documentation and record-keeping, and knowledge sharing involving all levels of the plant workforce from the management to workers. Further, protecting people on the job is in the best interests of the plant owner. The enhancement of plant safety will add value to the plant by uprating work efficiency and improving plant economy, which will help the utility build a good reputation in the sector.
As per the CEA, an analysis of causes of fire incidents reveals that the majority of fires could have been perhaps be prevented and the extent of damage be minimised, if fire safety measures had been strictly enforced. Fire safety measures must be adopted right at the design stage. Proper upkeep of the fire protection equipment/systems will ensure timely availability of the system for putting out the fire, before it could result in a disaster. The crisis on account of fire could be greatly reduced or by averted adopting modern and state-of-the-art technology for fire detection and monitoring systems. The success of fire safety measures would lie in minimising damages and an early restoration of plants and equipment. The early detection of fire and swiftness in firefighting can definitely turn a major disaster into a minor accident.
Also, in large power plants, electrical systems covering voltages from 110 V to 400 kV are distributed in a complex network. Thus, in a power generation environment particularly, chances of electrocutions are quite high. Electrical current can damage or destroy property and seriously injure anyone in close proximity. Electrical flashover is a common kind of accident that disturbs the smooth running of systems. Many workers are injured and killed every year while working on energised equipment. Those who work with or near electrical current on a regular basis need safety training to protect themselves and their co-workers. With proper training, electrical workers can learn vital hands-on skills and complete their duties efficiently and safely.
These skills will help understand which personal protective equipment (PPE) is appropriate for each job and the proper way to use this equipment, recognise the signs of potential danger and the safety steps to take, safely perform repairs and maintenance in areas with high voltage, avoid serious accidents that could cost lives or millions of rupees in equipment, product or output, and learn about the official safety standards, recommendations and guidelines related to work.
For example, the National Safety Council comes out with publications on industrial and power plant safety, while the National Power Training Institute (under the power ministry) conducts such training programmes.
Some design-related safety measures that can be incorporated include ensuring that busbars in the switchgear, motor control centres and panel boards are insulated so as to reduce the arc fault and also to help in the self-extinction of arc fires. Further, current-limiting devices such as fuses and circuit breakers may be used, instead of current-protective devices. Splitting of large load, single distribution boards to different independent sections can be done to limit the fault current. For high capacity LT motor feeders, dual element fuses can be used. Also, the use of residual earth leakage, circuit breakers in low voltage circuits, particularly in welding supply sources, can be promoted.
For NTPC, the country’s largest power generator, health and safety are key priorities. There is a three-tier structure for occupational health and safety management at stations/projects, at the regional headquarters and at the corporate centre. The business unit head and senior management carry out regular plant inspection and review. Internal safety audits of all project sites by their own safety officers as well as external safety auditors are regularly carried out and complied with. Cross-functional safety task forces are functional at all projects and stations to monitor unsafe working conditions and rectify them accordingly. Effective engineering controls are provided at all operating stations to indicate and handle on-site emergencies. Detailed emergency plans have been developed and responsibilities assigned to each concerned to handle such situations. Mock drills are also conducted regularly to check the health of the system.
The way forward
Over the past few years, the risk of cyberattacks across various segments of the power sector has increased. This is due to the increasing complexity of the system; new customer touchpoints in utilities; introduction of a smart grid infrastructure such as advanced metering and demand-side management; and increase in interconnections and integration, among others. Ensuring physical security is one of the primary ways to prevent cyberattacks. Vulnerable areas such as control centres should be notified as restricted, allowing entry only to authorised persons. The control room and computer room doors should be equipped with access security systems for protection against intrusion and surveillance should be undertaken for integrity checks. Moving ahead, there is a need for the harmonisation of various standards and guidelines on cybersecurity of power systems in India. The formulation and enactment of a cybersecurity policy for the Indian power sector must be in sync with CERT-In response teams for transmission, thermal and hydro.
An emerging trend in power plant safety is the use of digital solutions. Apart from this, depending on plant requirements, developers are using robots that can be remotely operated for monitoring operations in areas that have security concerns. With robots, the task can be completed in a more safe and efficient manner. The digitalisation of plant operations also helps maintain safety. With the use of internet of things and predictive maintenance tools, real-time plant performance data can be obtained and anomalies in performance parameters identified. Besides, with a detailed analysis of plant performance, potential hazards can be averted. Further, power utilities must stay connected with the nodal agency to get the necessary assistance for cybersecurity.
Ensuring safety in power plant operations is essential as any negligence could lead to accidents. These accidents could range in severity from minor incidents to major boiler blasts. There must be regular safety audits across the country’s thermal power fleet, besides stepping up routine maintenance and repair works. Going forward, there is a need to have a system for the early detection of equipment issues as soon as pressure builds up to dangerous levels and temperatures rise beyond the accepted safety level.