Hello learners. I am here to discuss about HVAC and fire protection systems for substation under working principle requirement and importance. To start with this session, let me ask how many of you are aware of air conditioning system and how does it work? Of course, all of us will have air conditioner at our homes. It is required not only in home, but almost in all sectors such as airports, shopping malls, laboratories, hospitals, hotels, and factories, etc. Now, let us learn what is cooling, and what is air conditioning, and what is their importance in substation? Cooling is nothing but removal of heat from the space, and air conditioning is a process in which both temperature and humidity is being controlled simultaneously in the given space. As an electrical engineer, I hope you are aware that the substation comprises of heat dissipating components such as electrical panels, switch gears, light fittings, batteries, and cables, etc. Power dissipation or energy loss in these components takes place in the form of heat and temperature of these components rise. This will increase the room temperature, which in turn will affect the equipment performance. Also, you can note that humidity is playing a major role. Humid, the excess moisture in the space will start condensing on surface of the panels, which leads to corrosion. If condensed water enters inside he electrical equipment, or if condensation occurs inside of the electric equipment it may lead to flash over, thus, life of equipment is reduced. To control both the temperature and humidity, air conditioning system is required. Next we'll see the sources of heat. We are going to learn about the sources of heat for arriving air conditioning requirement. We have two forms of heat, namely sensible heat and latent heat. What is sensible heat? Heat that causes a change in temperature is called sensible heat. What is latent heat? Heat that causes a change in state with no change in temperature is called latent heat. I am giving you the example for this. Water will get evaporated when reaches its boiling point. Here, what is happening, temperature is changing from 35 degree Celsius to 100 degrees Celsius. This change in temperature is called sensible heat. Now, I'm going to explain what is latent heat. If the water further getting heated up, what will happen? It tends to evaporate. I'm I right? Here, liquid phase to vapor phases change. This change in phase is called latent heat. Next, let's see the sources for sensible and latent heat. Solar and transmission heat gain through the wall, floor, glass, roof, and heat gain from equipment, lighting, ventilation, and fan motors are called sensible heat. Heat gained from human beings, outdoor air, infiltration are called latent heat. I hope all of you understood the two forms of heat and its sources. Now, let us learn about the inputs requirement for HVAC design. It is common that electrical equipment in the substation will dissipate heat. So it is the responsibility of electrical engineer to give the heat dissipation details. These details will be obtained from electrical equipment manufacturer. Now, let's see the inputs required from electrical and civil engineer to estimate HVAC capacity. Inputs required from electrical engineers are: equipment heat dissipation detail, number of personnel in the room, lighting loads, and temperature to be maintained if specified by manufacturer. Input required from civil engineers are: architectural layout, u-factor for walls, roof, and floor. Thus after receiving all the able inputs, we estimate heat load calculations, and finally, air conditioning capacity has been derived. Hope you understood the required basic details for HVAC design. Next, let's discuss about the fire protection system and its importance in substation. From self-paced learning, we learned about what is fire. That it is a chemical reaction. It consists of three elements. If any one of the elements is removed, the fire will not prolong. But we may be less aware about the impact of fire. The major impacts are: it disrupts power supply to customers, failure of measuring equipments leads to huge financial loss, threats to human life and surroundings. First and foremost, we must assess fire hazards and risks involved in substation, and we should get up it's appropriate fire protection measures in substation. When we talk about fire protection, we all think about higher-end system, sprinkler system, and spray system. For instance, in this operation, we are using fire extinguisher to suppress small fire to avoid further fire propagation. This extinguishers will be located not only in substation, but almost in all the buildings because it comes in handy and easily operated by anyone. Imagine that there is a small fire in substation, but you do not know how to operate the extinguisher. Don't worry, now I'll give you a simple tip to make you a savior, that is how to operate the extinguisher. One thing you remember the word PASS. What is PASS? It is a symbol abbreviation, P stands for pull the pin, A stands for aim at base of fire, S stands for squeeze the lever, and S stands for sweep side-to-side of fire location. Hence, remember always the keyword PASS. I hope you all understood how to operate extinguishers in case of small fire. Now, let us see what is high velocity water spray system, which is being used for protecting the transformers or reactors. Based on the oil capacity, the requirement of high protection system will be designated as per national standards and specification. Now, as you see, transformer comprises main tank, radiator bank, and conservator. To arrive water quantity, the surface area of the other components to be estimated fast. We can get the details from the GA drawing, which can be obtained from transformer manufacturers. Also, note that we are to get transformer foundation layout to locate pipe support which will be fitted surrounding the transformer. After adding all the surface area of the transformer components, water demand has been calculated by multiplying the design density with overall surface area of transformer. Now, let us see a visual regarding HVWS system operation. In fire condition, the quadrat bulbs are broken at 7-9 degrees Celsius, thus reducing the pressure in the direction line, which in turn allows the pressurized water from the deluge valve. The pressurized water will flow through the nozzles, which is fitted in a ring network around the transformer. Thus it cool the surface and does not allow oil to form pools, which will control or reduce the spread of fire to nearest building or equipment. I hope this session was interesting and you understood MEP system used in substation.
