Welcome to this module on fire protection systems and HVAC for Substations, Fire Protection System. This topic explains the importance of fire protection system, fire and its classification, fire protection system and its types. Working principles of hydrant system and water spray system. A fire protection system reduces damage to expensive electrical equipment assets and documents. It prevents loss of life due to fire incidents. It enables the facility to recover easily after the fire incident. It also enables resumption of operation as soon as possible, since the damage is less as compared to that an unprotected building. Thus it prevents all reduces loss of life and revenue. Fire protection system for the substation shall be proposed based on the potential fire hazard perceived. The following are the potential fire hazards in substation. Explosion in oil filled transformer, arc flash in LV or MV switchgear, short circuit in electrical equipment like transformers, LV or MV switchgear and cables will lead to spark and fire. Loose connection or termination of power cables may increase the temperature at the terminal and we lead to spark and fire. Increase in concentration of hydrogen in battery room may lead to explosion. Improper ceiling of openings will spread the fire from one room to another room. Fire is a chemical reaction, it occurs between oxygen in the air and combustible substance with the help of ignition source. The combustible substance must be heated to its ignition temperature for compassion to occur, the reaction will continue to take place only as long as there is enough ignition source combustible substance and oxygen. Fire protection system shall have proven efficacy in removing or subduing any one of these three elements. A substation by and large is designed without using combustible materials. However, usage of some combustible materials like transformer oil and insulating materials cannot be avoided and hence fire protection system have been designed to either deplete oxygen or cool ignition sources. Fire and its classification. The three classes of fire are Class A, class B, and class C. The class they fired includes fired in ordinary combustible materials such as wood, cloth and paper. The class B fire includes fire in flammable liquids, combustible liquids, petroleum greases, tars, oils, oil based paints, solvents and alcohols. The class A fire is due to live electrical equipment. Some important systems in fire protection are active system, passive system and life safety. Active system includes portable extinguisher fire hydrant fire sprinkler, fire detection and alarm system, water spray system and gas based suppression system. The passive system includes fire doors, small curtain, fire sealants and fire retardant paints. The life safety includes compartmentation, minimize escape paths, means of egress and safety signage. The different types of extinguishers are water extinguishers, form extinguisher carbon dioxide extinguisher and dry chemical extinguishers. The different class of fire class A, class B and class C are shown on the screen. For class A of fire, water extinguisher, yes, form extinguisher, yes, carbon dioxide extinguisher, no, dry chemical extinguisher, yes. For class B of fire, water extinguisher, no, form extinguishers, yes, carbon dioxide extinguisher, yes, dry chemical extinguisher, yes. For class C of fire, water extinguisher, no, form extinguishers, no, carbon dioxide extinguisher, yes, dry chemical extinguisher, yes. Fire hydrant system provides, pressurized water at designated outlets so that by using host pressurized water can be forced upon the fired location. Next, let us learn the components of a hydrant system. The fire hydrant system comprises off water storage tank, fire bumps, pipes and valves, hydrant valves, hose boxes, hoses and branch pipe nozzle. Fire pump house consists of electrical motor driven pump and diesel engine driven pump and jockey pump. Motor driven pump will function as main fire pump and engine driven pump will function as standby. Electrical motor revenge jockey pump will act as a pressure maintenance pump. How does a fire hydrant system work? The hydrant pipe ring main is laid underground or above the ground throughout the switchyard peripheral with hydrant valve spaced as per standard interval. The hose box consisting of horses and branch pipes is placed adjacent to the hydrant valves. The entire pipeline networks are pressurized to the required pressure and connected to the pumping system. In case of fire, the personnel will operate the hydrant by connecting the host branch pipe and hydrant valves by coupling. Once the hydrant valve is opened, the water will come out through the hose nozzle at high pressure. This water has to be targeted at the fire location to suppress the fire. When the water discharges at high pressure, a pressure drop in ring main will be sensed by the pressures, which at set limits. This drop in pressure will switch on the fire pumps automatically to pump water from the water storage tank to support the operation of hydrant. If the pressure drop is minimal due to any leak in the system, jockey pump will be switched on instead of fire pump. Periodic maintenance should be carried on the bumps and the system for proper functioning of the system during an incident. Nitrogen injection system. Nitrogen injection system is provided for very large transformer. It enables forceful injection of nitrogen into the transformer on detection of heat beyond permissible limits. Injection of nitrogen will deplete oxygen and thus quenching the fire. Know that hydrant system is usually provided for substation up to 33 by 11 kV, only if necessary. Let us learn how a high velocity water spray system works. This system is used for the protection of large transformers and reactors in the substation. It will emulsify the inflammable liquid and does not allow fuel pool for fire. The fire is detected by the quartzoid bulbs fitted in the detection line. The network of spray nozzles arranged around the equipment to be protected. The minimum running water pressure at any projector shall not be below 3.5 bar. The quartzoid bulbs are broken at 79 degrees Celsius, thus reducing the pressure in the detection, which in turn allows the pressurized water from the deluge valves. Pressurized water is directed towards protected objects toward deluge valve, from a pipe network laid exclusively for the spray system. Next is the medium velocity water spray system. This system is used for the protection of cable walled and cables in cable tray. Water under pressure is directed to the nozzles through a deluge valve from a pipe network laid exclusively for the spray system. The minimum running water pressure at any nozzle shall not be below 1.4 bar. The deluge valve activated by mechanical means using quartzoid bulb. The deluge valve may also be activated electrically by solenoid actuator on sensing heat by heat detectors. Here is a quick recap of what you have learned thus far. Major potential fire hazards in substations are, explosion in oil filled transformer arc flash in LV or MV switchgear. Short circled in electrical equipment like transformers, lbr MV switchgear and cables will lead to spark and fire lose connection or termination of power cables may increase the temperature at the terminal and will lead to spark and fire increase in concentration of hydrogen in battery room may lead to explosion. Improper ceiling of openings will spread the fire from one room to another room, combustible substance, ignition source and oxidants are the main elements for compassion to our earth and it is known as fire triangle Fire protection system shall have proven efficacy in removing or subduing any one of these three elements. Fire due to combustible materials is class a fire fire due to flame. A Ble liquids is class B. Fire fired you to live electrical equipment is Class C. Fire. Fire hydrant system provides pressurized water and designated outlets so that by using hosts, pressurized water can be forced upon the fire location. Different types of extinguishers and their users are based on the classification of fire. Major components of fire hydrant system are water storage tank fired bumps that is made motor driven fire pump, stand by engine driven fire pump and for pressure maintenance, jockey pump, pipes, valves, nozzle and horses horse box. High velocity water spray system is used to protect large transformers and reactors. Medium velocity water spray system is used to protect the cable walls and cables in cable tray.
