Electrical funda

 SCR- silicon control rectifier Construction 1. Anode and cathode region are highly drop where gate as moderately drop and drift layer are lightly drop. 2. SCR can be visualized as too BJT (PNP) and ( n p n) connected together 3. SCR is the minority carrier device and it has three p n junction . Disadvantage of SCR 1. Switching is very least while T-off highest  2. More switching loss 3. More conductivity modulation , least R-oN  4. Minimum oN state drop and minimum conductivity loss  # SCR contains three p n junction J1 anode and drift - anode is highly drop , depletion low J2 drift and gate - lightly drop , depletion low J3 gate and cathode - highly drop , depletion low Since there is light dropping on both side of J2  So breakdown voltage is high for junction J2  Reverse blocking Let ,            Anode is connected to negative terminal of supply which cathode is connected to positive terminal of supply  1. J1 and J2 rev...

definition of air preheater air preheater increase the temperature  of the air. It is most commonly used in thermal power plant. And it is increase the efficiency of the boiler. Working of air preheaters (APH) 1. The hot fuel gas from the economist first enters the air preheater. Then those gases go through the tube to the chimney. The air mass then enters the preheater through the air inlet.  2.  Then both air and fuel gas flow in opposite directions.  3. baffles are provided in the air preheater to provide more time for exchanging heat from fuel gas to air   4. thus heat is absorbed by the air from the fuel gas. 5. this preheater air is supplied to the furnace.  construction   1. A tubular type air preheater is a large number of tube . 2. the fuel gas pass through the tube. 3. air flows over the tube. 4. baffles are provided to pass the air b number of time over the tube.  5. a soot hopper is provided at the bottom to collect the soo...