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Construction Of Welding Machine
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Now let assume a load having a power factor such that the secondary current is in phase with E2 the primary current must now have two component.
1. I1 to maintain the useful flux
2. I2 to neutralize the demagnetizing effect of the secondary current.
Since the flux of each limb is link only with the winding by which it is produced, it is referred to as leakage flux and its responsible for reducing an e.m.f. of self inductance in the winding with which it is linked.
The reluctance of the part of the leakage flux x OL is almost entirely due to the long air part and is therefore practically constant. Consequently, the value of the leakage flux is proportional to the load current whereas the value of the useful flux remains almost independent of the load.
The reluctance of the paths of the leakage flux is very high so that the value of this flux is relatively small even on full load.
From the above, it follows that the actual flux in a transformer can be regarded as being due to the two component namely:
i) The useful flux Ou, link with both winding and remaining practically constant in value at all loads.
ii) The leakage flux OL, half of which is linked with the primary winding and half with the secondary and its value is proportional to the load.
5.4 METHODS OF REDUCING LEAKAGE FLUX
The leakage flux can be reduced when the half of primary and secondary winding were placed concentrically or side by side in each limb of transformer. The primary and secondary winding were always interleaved to reduce leakage flux.
5.5 TRANSFORMER FABRICATION
The element of transformer consist of two coil having neutral inductance and a laminated steel core. The two cores are insulated from each other. The secondary parts are:
-Lamination
The core is constructed of transformer sheet metal laminated and assembled to provide continuous magnetic path with a minimum of air gap induced. The thickness of the lamination used is 0.35mm for a frequency of 50Hz. The eddy current loss is minimized by laminating the core, the core lamination is in the form of strips.
The joint in the alternate layers are staggered in order to avoid the presence of narrow gap through the cross-section of the core such staggered joints are said to be lubricated copper conductor.
In the design calculations, a 12 S.W.G. copper wire is used as a primary core land it is wound for 240 turns, copper conductor is used because of its advantage over aluminium, aluminium get burnt easily and break or cut easily when bent.
-Aluminium Conductor
From the design calculation, aluminium wire is used as the secondary coil and it is wound for 60turns. Aluminium conductor is used here in order to reduce weight of the transformer and cost. And by using a large cross sectional area of aluminium. It can withstand the high current present in the secondary side.
-Paper Insulation
Thick cement paper is used as the insulator for both the copper and aluminium conductors respectively. The cement paper is wounded round the conductors and starched to make it strong.
5.4.1 TYPES OF TRANSFORMER FABRICATION
Constructional, the transformer are of two type distinguished from each other by the manner of the primary and secondary coils which are placed around the laminated steel core. The two types of transformer are:
i) The core type transformer
ii) The shell type transformer
(i) The core type transformer: In the core type transformer, the winding surrounds a considerable parts of the core whereas the shell type
(ii) The shell type transformer: The winding surrounds a considerable portion of the winding as shown stremedically in the figure.
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ABSRACT - [ Total Page(s): 1 ]ABSTRACT COMING SOON ... Continue reading---
CHAPTER ONE - [ Total Page(s): 2 ]CHAPTER ONE1.0 INTRODUCTIONIn the past with the necessary of metals it always seems impossible to join two metals together with grooving riveting, this idea leads to alternative of finding a lasting solution to the problem. This brought about the idea of a welding machine with a well laminated core and coil wound together to form a high rated transformer which is immersed in a can of oil.Welding is the most economical and efficient way to join metals permanently. It is the only way of join ... Continue reading---
CHAPTER TWO - [ Total Page(s): 3 ]ii. OXIDIZING FLAMEOxidizing welding flame are produced hen slightly more than one volume of oxygen is mixed with one volume of acetylene. To obtained this type of flame, the flow of oxygen is then increased until the inner cone is shortened to about one tenth of it original length when the flame is properly adjusted, the inner cone is pointed and slightly purple. An oxidizing flame can also be recognized by it distinct hissing sound. The temperature of this flame is approximately 6300oF ( ... Continue reading---
CHAPTER THREE - [ Total Page(s): 4 ]CHAPTER THREE3.0 GENERAL DESCRIPTION AND ITS WORKING PRINCIPLERegarding the design and fabrication of this project several information were gathered through consultation of previous journals text books and internet.Definition: “welding is the process of joining together two pieces of metal so that bonding take place at their original boundary surface s. when two parts to be joined are melted together, heat or pressure or both is applied and with or without added metal for formation o ... Continue reading---
CHAPTER FOUR - [ Total Page(s): 4 ]Where;K = constant (Boltzman constant in joules / kelvin)A= 200m x 4 = 800mmT2 = 3500CT1 = 3150CX = 50mmQ = k x 800mm 350 – 3150C 50mm Where K =8.617 x 10-5 J/kQ = 8.673 x 10-5 x 800mm (135 50mmQ =62044.46 J/K 4.1 WINDING DESIGNThe
basic of winding is to have number of turns being wounded around an
appropriate point of the core. Winding design in transformer
construction must be done perfectly and accura ... Continue reading---
CHAPTER SIX - [ Total Page(s): 1 ]CHAPTER SIX6.0. CONCLUSION AND RECOMMENDATION6.1 CONCLUSION The project is a form of providing student with appreciable skills p4actically designed to expose or equip them with real working operation of machine and how they are being constructed and a better understanding of one’s own career goals and for the progress of the nation.The project seemed easy and simple but later on turn to be useful and interesting project for Engineering students. With all the proble ... Continue reading---
REFRENCES - [ Total Page(s): 1 ]REFERENCESFlood CR (1981) “Fabrication of welding and joining process†1st Edition, Butterworth and Co publisher limited London, P.P 21 – 25, 28 36- 37 and 39.Google: http://weldguru.com/welding-flamesFlood CR and parkin N. (1974) “craft practice “ 1st Edition pergamon press limited, New YorkDavies A.C (1984) “Welding science and technology†8th edition Cambridge Universities press. London Pg-42B.L. and A.K.Therage (1994 Textbook of Electri ... Continue reading---
