Energy Conversion(uptu) Dcm/c Iec Assignment

DEPARTMENT OF ELECTRICAL ENGINEERING IEC COLLEGE OF ENGINEERING GREATER NOIDA TUTORIAL SHEET-1 Instructor: Ramesh Singh Due Date: 1.

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16-03-09

A 4 pole DC motor is lap wound with 400 conductors, the pole shoe is 20cm long and the average flux density over one pole pitch is 0.4 T, the armature diameter is 30cm. Find the torque and gross mechanical power developed when the motor is drawing 25 a and running at 1500 RPM. A 220 V DC generator supplies 4 KW at a terminal voltage of 220 V, the armature resistance is 0.4 Ω. If the machine is now operated as a motor at the same terminal voltage with the same armature current, calculate the ratio of generator speed to motor speed. Assume that the flux per pole is increased by 10%as the operation is changed from generator to motor. A DC shunt generator driven by a belt from an engine run at 750 RPM while feeding 100 KW of electrical power in to 230 v mains. When the belt breaks it continues to run as a motor drawing 9 KW from the mains. At what speed would it run? A 250 KW, 400 V, 6 pole, DC generator has 720 lap wound conductors. It is given a brush lead of 2.5 angular degrees (mech.) from the geometric neutral. Calculate the cross and demagnetizing turns per pole. Neglect the shunt field current. Calculate the number of conductors on each pole piece required in a compensating winding for a 6 pole lap wound DC armature containing 286 conductors. The compensating winding carries full armature current. Assume ratio of pole arc to pole pitch = 0.7. A 440 V, 4 pole, 25 KW, DC generator has a wave connected armature winding with 846 conductors.The mean flux density in the air gap under the interpoles is 0.5 Wb per square meter on full load and the radial gap length is 0.3 cm. calculate the no. of turns required on each interpole. A compensated Dc machine has 20000 Ampere turns per pole. The ratio of pole arc to pole pitc is 0.8. the interpolar air gap length and the flux density are 1.2 cm and 0.3 T respectively. For rated armature current of 1000 A, calculate the compensating winding ampere turns per pole and the no. of turns on each interpole. Find the resistance of the load which takes a power of 5 KW from a shunt generator whose external characteristics is given by the equation V = 250 – 0.5 IL A 6 pole DC machine has 300 conductors and each conductor is capable of carrying 80 A without excessive temperature rise. The flux per pole is 0.015Wb and the machine is driven at 1800 RPM. Compute the total current, emf, power developed in the armature and electromagnetic torque, if the armature conductors are: a) wave connected b) lap connected. A 24 KW, 250 V, 1500 RPM separately excited DC generator has armature circuit resistance of 0.1Ω. The machine is first run at rated speed and the field current is adjusted to give an open circuit voltage of 260 V. compute terminal voltage of the generator under these conditions. Field flux remains unaltered.