Deepakkumar Yadav
Factors on Which Life of Insulation Depends Q. State the factors on which life of Insulation depends. Temperature : The insulation resistance decreases with temperature. The dielectric loss increase with temperature. The resistivity of the insulating material decreases by increse in temperature. The same can be expressed as Rt = R0 (1 – α0t ), … Read more
How Following Crackle Test is Carried for Transformers Q. Explain how following test is carried for transformers : Crackle test. Crackle test The objective of this test is to determine the presence of water or moisture in the oil. In this test a sample of transformer oil under test is taken in a test tube. … Read more
How to Prevent an Electrical Machine During its Inactivity Q. How to prevent an electrical machine during its inactivity? If the machine remains un-operated and kept idle for a long time it will not work properly and even may fail to operate. The reasons being : Moisture, din, dust from the surroundings is absorbed and … Read more
Methods of Purifying and Drying Out of Transformer Oil Q. State the methods of purifying and drying out of transformer oil and explain any one method brief with neat sketch Q. Explain the filtering process for transformer oil filtration. Purifying of transformer oil : There are mainly following three types of oil filter in common … Read more
Causes of Low Insulation Resistance of Electrical Equipment Q. What are the causes of low insulation resistance of electrical equipment and how will you made it high? The equipment may have : Low value of volume resistance. Surface resistance may be lower. Dielectric strength must have been lower. Dielectric constant (∈) may be lower. Dielectric … Read more
Agents which Contaminates the Insulating Oil Q. List the agents which contaminates the insulating oil. The insulating oil gets contaminated when the following impurities are present in it. The impurities will reduce the dielectric strength of oil and further in may loose its dielectric and insulating properties. Water Dirt / dust Carbon deposits Sulphur Acids … Read more
Uses of Filler Gauges Q. Explain the use of : Filler gauges The air gap should always be checked after dismantling and reassembly, it is also a part of routine maintenance, particularly in case of sleeve bearing machines. These apertures are usually plugged to exclude dirt, and the screwed plugs must be removed to permit … Read more
Measurement of D. C. Resistance of a 3-phase Induction Motor Q. State any two tests that are preferred on induction motors. Explain these tests in brief Measurement of D. C. Resistance of a 3 – phase Induction Motor : The state of the 3- phase induction motor may be star connected or delta connected. The … Read more
Types of Extinguishers Q. State different types of extinguishers. Which one is effective ? The following types of extinguishers are portable, and in smaller sizes, can be operated with ease by one person. These extinguishers are primarily intended to one against fires in their initial stage, at the seat of the fire. Dry Powder Extinguishers : … Read more
Properties of Transformer Oil Q. 10 List the properties of transformer oil Water content Acidity Density Flash point Fire point Purity Viscosity Dielectric strength Sludging