Last Answer : The type of dc generator used for arc welding purposes is a Differentially compound generator.
Description : The required DC voltage for arc welding is- (1) 6 to 9 V (2) 50 to 60 V (3) 200 to 250 V (4) 90 to 100 V
Last Answer : (3) 200 to 250 V
Description : When MMA welding what will be the effect on the weld f the power source was changed from AC to DC-ve? a) None b) Higher deposition rate c) It would slightly increase the depth of penetration d) The arc would become unstable
Last Answer : b) Higher deposition rate
Description : A butt weld has been made by MMA in a 50mm thick impact tested steel plate. The welding electrode used was a basic type, 5mm diameter. The measured welding parameters for one of the runs was 250 amps, 24 volts, using DC ... given to calculate the arc energy b) 1.9 kJ/mm c) 1.87 kJ/mm d) 2.0 kJ/mm
Last Answer : d) 2.0 kJ/mm
Description : Arc welding uses following electric supply (A) ac (B) dc (C) both ac and dc (D) spiral waveform
Last Answer : both ac and dc
Last Answer : Arc blow is a welding defect which is encountered in arc welding using a.c. current.
Description : Argon is used in arc welding because
Last Answer : Argon is used in arc welding because A. low reactivity with metal B. ability to lower the ... of metal C. flammability D. high calorific value
Description : What type of arc welding equipment is necessary when participating in arc welding?
Last Answer : The most important equipment you can have is your safety equipment, your gloves, visor and heavy-duty clothing. You have to have some sort of a power source to generate the electricity necessary for arc welding, so I'd say a power source is your most important arc welding equipment.
Description : In arc welding, Argon is used because of its - (1) Low reactivity with metal (2) Ability to lower the melting point of the metal (3) High flammability (4) High calorific value
Last Answer : (1) Low reactivity with metal Explanation: In arc welding, Argon is used as a shielding gas because it is chemically inert and forms no compounds. At the high temperatures that welding requires, the ... to brittle welds and instability in the welding arc. So,argon and other inert gases are sprayed.
Description : Projection welding is (i) Electric arc welding (ii) Gas welding (iii)Spot welding (iv) None
Last Answer : (iv) None
Description : Which type of welding is generally used in automobile sector? a) Electric arc welding b) Electric resistance welding c) Gas welding d) Forge welding
Last Answer : b) Electric resistance welding
Description : Among gas and electric arc welding, which has the higher rate of heating? a) Gas welding b) Electric arc welding c) Gas welding and electric arc welding have equal rate of heating d) Cannot be determined
Last Answer : b) Electric arc welding
Description : Rails in the field are generally welded by using a) Thermit welding b) Gas welding c) Electric arc welding d) Forge welding
Last Answer : a) Thermit welding
Description : The electric arc welding is a type of ............. welding. (a) forge (b) fusion
Last Answer : b) fusion
Description : Thermit welding is categorised as the __________ welding. (A) Forge (B) Fusion (C) Resistance (D) Arc
Last Answer : (B) Fusion
Description : Consumable electrodes are used in the __________ welding. (A) Gas (B) Arc (C) Thermit (D) Resistance
Last Answer : (B) Arc
Description : Projection welding & stud welding is categorised as the __________ welding. (A) Pressure (B) Thermit (C) Resistance (D) Arc
Last Answer : C) Resistance
Description : Which of the following mainly decides the current to be employed is arc welding? (A) Electrode size (B) Plate thickness (C) Voltage across the arc (D) Welded portion length
Last Answer : (A) Electrode size
Description : Coating provided on the electrodes used in the arc welding is not expected to (A) Add alloying elements (B) Prevent electrode from contamination (C) Stabilise the arc (D) Provide protective atmosphere to weld
Last Answer : (B) Prevent electrode from contamination
Description : Cold cracking in the heat affected zone of a high strength steel weld can take place because of the (A) Retained austenite (B) Martensite formation (C) Relatively high sulphur content in the base metal (D) Sufficient hydrogen present in the welding arc
Last Answer : (B) Martensite formation
Description : Stainless steel is welded using (A) Oxy-acetylene flame (B) Oxy-hydrogen flame (C) Arc welding (D) Inert gas arc welding
Last Answer : (D) Inert gas arc welding
Description : What is a typical ARC voltage setting when welding with the TIG (GTAW) process? a) 18-20V b) 24-26V c) 10-12V d) 70-90V
Last Answer : c) 10-12V
Description : Explain the shielded metal arc welding (SMAW) processes with neat sketch. State its two advantages and disadvantages.
Last Answer : Working : Shielded metal arc welding uses a metallic consumable electrode of a proper composition for generating arc between itself and the parent work piece. The molten electrode metal fills the weld ... . 2. Weld may contain slag inclusions 3. Fumes make difficult the process control.
Description : List common equipments used for arc welding process.
Last Answer : 1. A.C. or D.C. machine 2. Electrode (bare or coated) 3. Electrode Holder 4. Cables and its connectors 5. Chipping Hammer 6. Earthing Clamps 7. Wire-brush 8. Helmet 9. Safety Goggles 10. Hand Gloves 11. Apron Sleeves etc.
Description : Describe the working principle of Arc Welding.
Last Answer : Arc welding is the most extensively employed method of joining metal parts. Here the source of heat is an electric arc. The arc column is generated between an anode which is the positive pole of D.C. ... also melted and is transferred in to the metal in the form of globules of molten metal.
Description : Compare resistance welding and arc welding.
Last Answer : Sr. No Resistance Welding Arc Welding 1 It is plastic welding It is fusion welding. 2 Arc is produced by heat due to resistance of flow of current by work and by application ... 8 Less skilled operator can do the job. More skilled operator is required to the job
Description : Draw a schematic of a set up of shielded metal arc welding.
Last Answer : Fig. Shielded metal arc welding set-up
Description : In arc welding, Argon is used because of its (1) Low reactivity with metal (2) Ability to lower the melting point of the metal (3) High flammability (4) High calorific value
Last Answer : Low reactivity with metal
Description : Compare between Resistance welding and Arc welding on any six points.
Last Answer : Sr.No Parameters Resistance Welding Arc Welding 1 Type of welding Plastic/Pressure/Non-fusion welding Fusion/Non pressure welding 2 Principle of heat developed Heat ... It is suitable for mass production It is suitable for heavy job, maintenance and repair work
Description : The commonly used gases in tungsten arc welding are 1.Hydrogen and oxygen 2.Hydrogen and organ 3.Hydrogen and helium 4.Helium and argon
Last Answer : The commonly used gases in tungsten arc welding are Helium and argon
Description : For arc welding current range is usually (1) 10 to 15 A (2) 30 to 40 A (3) 50 to 100 A (4) 100 to 350 A
Last Answer : For arc welding current range is usually 100 to 350 A
Description : Identify the correct combination of respective Electric arc welding and Electric resistance welding methods : (A) Butt welding and Seam welding (B) Hydrogen shielding and Projection welding (C) Seam welding and Coated electrode welding (D) Coated electrode welding and Hydrogen shielding
Last Answer : Identify the correct combination of respective Electric arc welding and Electric resistance welding methods : (A) Butt welding and Seam welding (B) Hydrogen shielding and Projection welding ... Seam welding and Coated electrode welding (D) Coated electrode welding and Hydrogen shielding
Description : The supply for arc welding is :
Last Answer : The supply for arc welding is : Low voltage, high current ac or dc voltage
Description : What is the other name used for DC generators? A. Dynamos B. Alternator C. Capacitor D. Dynamotor
Last Answer : Dynamos is the other name used for DC generators.
Description : When using multiple SAW arc systems (twin wires etc), the arcs often have different polarities or use all AC rather than DC polarity, this is to? a) Prevent arc blow between arcs b) To maximize productivity c) To even out the power factor on the mains supply d) Make it easier to initiate the arc
Last Answer : a) Prevent arc blow between arcs
Description : Compare the AC and DC Arc lamps.
Last Answer : AC Arc Lamp DC Arc Lamp Cross section area of electrode is same Cross section area of electrode is positive rod is twice that of negative rod Series inductor is used for stability ... supply is used for DC arc lamp Luminous efficiency is less Luminous efficiency is high
Description : Which of the methods listed is used to maintain the division of load between two compound-wound, DC generators operating in parallel? A. The shunt fields are interconnected. B. The shunt ... generators are connected in series. D. The equalizer connection parallels the series fields of all machines.
Last Answer : Answer: D
Description : An equalizing connection between two compound-wound DC generators when paralleled, serves to _____________. A. reverse the polarity of the incoming generator as the series field weakens B. automatically ... the series field of the incoming generator D. parallel the series fields of the generators
Description : AC and DC generators are similar in that they _____________. A. both generate alternating voltages B. both rectify the voltage before delivery C. are constructed at the same physical size for the same kilowatt rating D. both supply three-phase power
Last Answer : Answer: A
Description : Modern DC generators are fitted with commutating poles to _____________. A. prevent motorizing B. reduce sparking C. reduce the load on the main poles D. reduce spring pressure on the brushes
Last Answer : Answer: B
Description : Which of the methods listed is used to maintain equal load sharing between two compound wound DC generators operating in parallel? A. The shunt fields are interconnected. B. The shunt field rheostats ... are connected in series. D. The series fields of both generators are connected in parallel.
Description : In a diesel electric plant, raising the generator's field excitation will cause the DC propulsion motor to ________. A. increase in speed B. decrease in speed C. affect generator speed only D. affect main motor speed if done in conjunction with higher generator engine speeds
Description : What Is Basic Principle Of Operation Of Alternators/dc Generators?
Last Answer : They are working on the fundamental principle based on Faraday’s Laws of Electromagnetic Induction. This law states that, When a current carrying conductor moves in magnetic field, it induces an EMF.
Description : What Are The Major Parts Of The Dc Generators?
Last Answer : Yoke Poles Field winding Armature Armature winding Commutator brushes
Description : What Are The Conditions To Be Satisfied For Parallel Operation Of Dc Generators?
Last Answer : The polarities of the generators must be same or the connections must be interchanged till they become same. The voltages of both the generators must be equal. The change of voltage with ... and negative terminals of generators must be connected properly to the positive and negative of busbar.
Description : What is the basic difference between the primaries of ac and dc rate generators?
Last Answer : The method of primary excitation (ac and permanent magnet).
Description : What are the three classifications of dc generators?
Last Answer : Series-wound, shunt-wound, and compound-wound
Description : Why are drum-type armatures preferred over the Gramme ring armature in modern dc generators?
Last Answer : Drum-type armatures are more efficient, because flux lines are cut by both sides of each coil.
Description : In DC generators, armature reaction is produced actually by (A) Its field current. (B) Armature conductors. (C) Field pole winding. (D) Load current in armature.
Last Answer : Ans: D Because load current in armature gives rise to armature mmf which react with main field mmf.
Description : DC GENERATORS MCQ
Last Answer : 101. Wave winding is composed of (a) any even number of conductors (b) any odd number of conductors (c) that even number which is exact multiple of poles + 2 (d) that even number ... increase the field resistance (c) increase the speed of primemover (d) check armature insulation resis¬tance Ans: a