Fire Safety of Industrial Buildings: Electrical Generating and Distributing Stations - Code of Practice
1993 Edition

For effective fire detection in electrical generating stations, it is recommended to install a combination of ionisation and optical smoke detectors within control and switchgear rooms, employing a cross-zoning strategy to reduce false alarms. Time delay mechanisms and intelligent microprocessor-based detection and suppression systems enhance reliability. In coal handling plants, early warning detectors like rate-of-rise heat sensors, infrared detectors, linear heat detectors, and optical beam detectors are advised to provide prompt fire alerts.

To safely operate hydrogen-cooled turbo-generators, maintaining hydrogen purity near 95% is essential to reduce explosion hazards. Continuous monitoring of hydrogen pressure and purity, use of oil pressure gland seals to prevent leaks, and locating hydrogen equipment in well-ventilated areas with proper venting to open air are critical. Additionally, preventing leaks of lubricating and hydraulic oils—which pose significant fire risks—is necessary, alongside monitoring mechanical integrity to detect vibrations or failures. Fire detection and extinguishing systems, such as CO2-based systems for stator windings, should be implemented for added safety.

Transformers under 10 MVA or with oil content up to 2000 litres generally do not require fixed fire protection systems. However, larger transformers exceeding 10 MVA or 2000 litres of oil capacity must be protected by high velocity water spray deluge systems designed for explosion risks, with deluge valve housings positioned outside fire zones and heat protected. Switchgear rooms should be equipped with automatic total flooding extinguishing systems such as Halon or CO2, controllable ventilation for smoke and heat management, and ionisation plus optical smoke detectors using cross-zoning and time delay principles. The rooms must be kept free from debris and combustible materials to minimize fire hazards.

To minimize fire hazards in coal handling and storage zones, adherence to IS 3595:1984 guidelines is essential. Key practices include segregating coal piles with fire breaks, early detection of fire location using suitable detectors, and removing heated coal by excavation to eliminate fire sources. Moisture levels should be managed carefully to prevent accelerated oxidation and spontaneous combustion. Firefighting equipment like extended branch pipes should be employed for effective water jet application, and clear access routes must be maintained for firefighting operations. Proper spacing and layout of storage piles are critical to contain fire spread.

Fire protection for oil storage tanks involves installing fixed foam systems conforming to IS 12835 (Part 1):1989 and extending external hydrant systems with 63 mm double outlets to cover tank areas. Fixed 38 mm water monitors must be positioned at strategic locations for cooling purposes. Electrical equipment, including turbo-generators and lubricating oil systems, require fixed water spray protection systems applied both beneath operating floors to manage pool fires and around bearing housings for oil fire risks. High velocity water spray systems delivering approximately 10 liters per minute per square meter should cover oil systems and associated components. CO2 or dry chemical systems can be used only as supplementary to water spray systems. Heat detectors complying with IS 2175:1988 are recommended for early fire detection.