Discuss in detail about armature speed control of DC shunt motor. 8 U CO1 May 2014 May 2012 A 500 V DC shunt motor running at 700 rpm takes an armature 8 Ap CO3 current of 50 A. its effective armature resistance is 0.4 What Ω. resistance must be connected in series with the armature to reduce the speed to 600 rpm, the torque remaining constant? Explain in detail the construction and working operation of 10 U CO1 Nov 2015 Retardation test on DC motor. Derive in detail the condition for maximum efficiency of DC machine. 6 Ap CO3 Explain the method to obtain efficiency at full load by conducting 16 U CO1 May 2016 Hopkinson’s test. The no-load test of a 44.76 kW, 220 V, DC shunt motor gave the 16 Ap CO3 May 2016 following figures: Input current = 13.25 A; field current = 2.55 A; resistance of armature at 750C = 0.032 and brush drop = 2 V. Estimate the full load current and Ω efficiency. With a circuit, explain how to obtain efficiency of D.C. generator by 16 U CO1 Nov 2016 conducting Swinburne’s test. In a Hopkinson’s test on a pair of 500 V, 1000 kW shunt generators, the 16 Ap CO3 Nov 2016 following data was obtained: Auxiliary supply, 30 V at 500 V: Generator output current, 200A. Field currents, 3.5 A 1.8 A. Armature circuit resistances, 0.075Ω each machine. Voltage drop at brushes, 2V (each machine). Calculate the efficiency of the machine acting as a generator. The speed of a 500 V DC shunt motor is raised from 700 rpm to 1000 6 An CO3 May 2011 rpm by field weakening, the total torque remaining constant. Ra and Rsh are 0.8 and 750 ohms respectively and the current lower speed is 12 A. calculate the additional shunt field resistance required assuming the magnetic circuit to be unsaturated. A 230 V motor has an armature resistance of 0.3 ohms and takes an 8 An CO3 May 2010 armature current of 40 A on a certain load. By how much must the main flux be reduced to raise speed by 50% and 25% if the developed speed is constant? Neglect saturation and armature reaction.
Discuss in detail about armature speed control of DC shunt motor. A 500 V DC shunt motor running at 700 rpm takes an armature current of 50 A. its effective armature resistance is 0.4 Ω. What resistance must be connected in series with the armature to reduce the speed to 600 rpm, the torque remaining constant? 8 8 U Ap CO1 CO3 May 2014 May 2012 Explain in detail the construction and working operation of Retardation test on DC motor. Derive in detail the condition for maximum efficiency of DC machine. 10 6 U Ap CO1 CO3 Nov 2015 Explain the method to obtain efficiency at full load by conducting Hopkinson’s test. 16 U CO1 May 2016 The no-load test of a 44.76 kW, 220 V, DC shunt motor gave the following figures: Input current = 13.25 A; field current = 2.55 A; resistance of armature at 750C = 0.032 Ω and brush drop = 2 V. Estimate the full load current and efficiency. 16 Ap CO3 May 2016 With a circuit, explain how to obtain efficiency of D.C. generator by conducting Swinburne’s test. 16 U CO1 Nov 2016 In a Hopkinson’s test on a pair of 500 V, 1000 kW shunt generators, the following data was obtained: Auxiliary supply, 30 V at 500 V: Generator output current, 200A. Field currents, 3.5 A 1.8 A. Armature circuit resistances, 0.075Ω each machine. Voltage drop at brushes, 2V (each machine). Calculate the efficiency of the machine acting as a generator. 16 Ap CO3 Nov 2016 The speed of a 500 V DC shunt motor is raised from 700 rpm to 1000 rpm by field weakening, the total torque remaining constant. Ra and Rsh are 0.8 and 750 ohms respectively and the current lower speed is 12 A. calculate the additional shunt field resistance required assuming the magnetic circuit to be unsaturated. 6 An CO3 May 2011 A 230 V motor has an armature resistance of 0.3 ohms and takes an armature current of 40 A on a certain load. By how much must the main flux be reduced to raise speed by 50% and 25% if the developed speed is constant? Neglect saturation and armature reaction. 8 An CO3 May 2010
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