Development of a Substation Fire Management Strategy and the implementation of a Hypoxic Fire Prevention System

摘要

ISO55001 defines asset management as the coordinated activity of an organisation to realise value from assets. One aspect of "value" includes the minimisation of risk and liabilities. Good asset management of substations requires the consideration of asset risks, e.g. substation protection and control rooms contain critical equipment that is vulnerable to fire damage. Risk is considered in substation design, procurement of equipment, during construction and in operation and maintenance. One of the significant asset risks within a substation is the potential for fire, with its management being considered in terms of prevention, minimisation or suppression. It is considered in respect of individual asset classes, as well as specific issues and the entire substation. The consequence of a fire is considered in regards if it is acceptable (manageable) or must be avoided at any level. There is also consideration in regards to existing older/aged substations versus more modern designs. The development of a substation fire management strategy has allowed TasNetworks (transmission and distribution network operator, Tasmania, Australia) to evaluate both existing and future fire management techniques to identify if existing practices are sufficient, and the locations where additional management should be considered and introduced. By using a defined approach to fire risk management, a consistent methodology could be applied across all the transmission substations owned by TasNetworks with detailed plans developed into short to medium term capital investment programs. Consideration for active or passive fire control in the event of a fire starting in a substation environment can include fire prevention or suppression. Traditional fire suppression (passive) methods activate post fire start and include sprinklers or gaseous suppression systems. These systems require significant ongoing maintenance and compliance checks. Fire suppression systems are prone to accidental discharges, can only operate once before requiring recharging and have high ongoing costs. In contrast, a hypoxic fire prevention system (active) is simple in concept, can operate continuously and has moderate ongoing costs. The hypoxic system is, in theory, superior to a fire suppression system in that it prevents the fire starting/spreading before any action occurs. Any smoke being produced is able to be detected by suitable smoke alarm system. Hypoxic fire systems operate by taking normal atmospheric air, separating the oxygen and nitrogen molecules, and injecting oxygen reduced/nitrogen rich air into the space to be protected. As a result, the normal oxygen level of 21 percent within the enclosure can be reduced to a level below the fire ignition threshold. The oxygen reduction system is not new technology, typically only used in areas to prevent deterioration of archives and cool stores to prevent oxidation of fruit. Modern applications include the prevention of fires within communications and data centres. Within a utility substation environment TasNetworks has the only known hypoxic fire prevention system in Australia. Reducing oxygen in the atmosphere can increase the risk to personnel health and safety, but is nominally considered a safe environment to undertake minor short duration tasks such as site inspections. In Australia, atmospheres with less than 19.5 percent oxygen are considered hazardous, and appropriate risk management must be undertaken. A trial installation at three transmission substation sites, including one approximately 60 years old, enabled the development of a specification around the key design and installation components of the hypoxic fire system including establishment of room tightness, overall control architecture and fresh air flushing requirements. This paper highlights: 1. the key aspects of the processes behind the development of a substation wide fire management strategy that TasNetworks has developed to ascertain the existing fire risk