The heat from the failed capacitor bank completely destroyed the main inbound 400-volt distribution board of a large shopping mall and spread the fire around the substation. The radiant heat released by this fire also destroyed the control panel and the emergency generator control panel located directly opposite.
Introduction to fire-fighting protection
Plant layout and building design play a major role in reducing the spread of fire and the effects of explosions.
For example, equipment and buildings should be arranged so that they have vents that rupture instead of allowing an explosion to damage the main fabric. Site supervisors should ensure that these vents are never blocked. In fire prevention, cleanliness and neatness are very important, as is the careful maintenance of tools.
Most fires are caused either by negligence or faulty equipment.
The choice of fire-fighting equipment depends on its suitability for electric fires, but also on the cost and extent of the power supply to the point. The types of portable manuals are as follows: halon gas of various kinds, chemical carbon dioxide foam, and powder.
Use of fixed sprinkler systems for water, carbon dioxide, and halon gas. Halon gas and carbon dioxide can suffocate personnel trapped in the landfill area.
Strict precautions must therefore be taken to lock the equipment in the presence of personnel. There is also the use of sand, blankets, and fire hoses. Fire doors are a very important means of limiting the spread of fire and ventilation systems should also be provided with automatic shutdown if not with automatic dampers in the event of a fire. Fire drills are also important and should not be overlooked on a construction site.
Wiring can also be a cause of serious fires with the risk of significant damage to the installation and danger to personnel. Low Smoke and Smoke Developed (LSF) cables are now available in a variety of forms, most of which will reduce flammability and release less toxic gases when heated.
the DC-Provisions ( UPS Batteries ) are a particularly important and vulnerable part of any facility. They are generally derived from stationary batteries which give off flammable and toxic gases.
Batteries should be in a separate room with an acid-resistant floor, special fixtures, a suitable sink, and an adequate water supply. It is wise to have an acid-resistant drainage system. The room should be well ventilated, but direct sunlight should not be allowed on the cells.
Considerations for fire-fighting safety in substations
The main fire risks and detection difficulties in substations arise from the following factors:
The formation of electric arcs and the formation of static electric charges in equipment.
Overheating of electrical control equipment, switchgear, and wiring.
Once initiated, a fire can spread rapidly due to the presence of large amounts of combustible materials in the form of hydrocarbons contained in wiring and insulation.
The environment in areas of uninterrupted power supply (i.e. the battery room) can become explosive due to the build-up of high concentrations of hydrogen.
Since substations are generally unmanned, early intervention by staff may not be possible in the event of a fire.
Zones Essential advised
Switch/relay room Ceiling √
Cabinet In / On √
Control room Ceiling √
Cabinet In / On √
Empty floor √
Return vent / duct √
Battery room Ceiling √
Return vent / duct √
Cable trench √
The high air movement caused by air conditioning dilutes and disperses the smoke.
Much of the mission-critical equipment is housed Ceiling mounted detectors can take some time to detect fires in cabinets and installation cabinets, especially since cabinet fires are typically long-lasting.
Underground trenches connecting the main areas of the substation are considered hostile environments. The high levels of background pollution present in these areas will affect the proper functioning of conventional detectors and constitute a source of false alarms.
Designed for effective fire protection
Table 1 below shows the operational areas of a substation where protection is required.
The switch room accommodates high-density electronic equipment housed in cabinets and automated switches. The equipment in the cabinet performs the main functions of the installation and constitutes the switching interface between the control room and the equipment in the field.
The area can also accommodate a large amount of counting and recording equipment. Due to the high volume of critical electronic equipment, it is essential to detect a fire before compromising the operation of the plant.
The control room is the main command center of the substation. The entire operation of the site is monitored and controlled from this central location.
A control room can range from a small, unventilated room that is rarely occupied, to a large air-conditioned area containing many staff and electronic equipment ( PCs, control panels/consoles, electrical and electronic switching devices, under-wiring). floor, etc. ).
The lead-acid battery room or nickel-cadmium batteries for the uninterruptible power supply (UPS) of the substation.
Battery rooms may consist of a slightly corrosive atmosphere ( sulfuric acid ). It is recommended to use a network of polymer sampling pipes in order to eliminate the risk of corrosion. In addition, it might be necessary to incorporate a Chemical Filter – a special filter designed to absorb corrosive gaseous contaminants.
A cable trench is located under the switch/relay room, control room, and battery room to house the communication, control, and power cables between the substation operating areas, as well as the transport of the energy to external high voltage switching towers.
The most effective way to protect a cable trench is to install a network of sample pipes in the top 10% of the trench.