Internship at Bharat Heavy Electricals Ltd.
For the first few weeks I was working in the transformer manufacturing department which dealt with the complete fabrication of different types of transformers (Power Transformers of up to 400 kV class / Traction Transformers Dry Type Transformers / Inst Transformers of up to 400 kV class and voltage transformer and current transformers) in 9 different bays.
I was assigned work in 2nd Bay where i assisted in performing following after assembly tests also known as NON DESTRUCTIVE TESTs (NDT).
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Ultrasonic test: To detect the welding fault on the transformer structure, high frequency ultrasonic energy was propagated through the material in the form of waves and at the fault place high amplitude waves were obtained.
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Dye Penetration test: This technique was used to detect the surface flaws. Red solution Dye was applied at the welding and then cleaned. After some time white developer is sprayed. Appearance of a red spot indicated a fault at the welding.
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Magnetic crack detection: This technique was used to detect the surface and sub-surface flaws. Magnetic field was created around the material followed by sprinkling of iron magnetic material powder at the welding. Sticking of the iron powder at the welding indicated a fault. Black Light (Ultra violet ) was used to detect the flaws.
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X-Ray Test:This technique was used to detect the surface and sub-surface flaws volumetrically. The weld spot was exposed to X or Gamma rays by using Industrial Radiography Exposure Divice (IRED) and the image was developed and the fault was seen in X-ray film. The commonly used source for gamma ray was Co-60 and high energy X-rays through linear accelerators.
I performed the listed Non destructive tests on :-
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Power transformers : a) Generator Transformers b) Auto Transformers
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Special types of transformers:- a) Freight loco transformers b) ESP transformers c) Instruments transformers
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Image of an ESP Transformer being taken down for NDTs
For the next weeks i spent my time in the Diesel electric shunting locomotives :
Diesel-electric locomotives come in three varieties, according to the period in which they were designed. These three are:
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DC - DC (DC generator supplying DC traction motors)
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AC - DC (AC alternator output rectified to supply DC motors) and
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AC - DC - AC (AC alternator output rectified to DC and then inverted to 3-phase AC for the traction motors).
I performed the study for all the three types and documented a report listing all the important parametrs of diesel locomotives at BHEL Jhansi.