Question Solved1 Answer A 25 kW, 50 V separately excited DC drive is operated at a constant speed of 3000 rpm with a constant field current such that the open-circuit armature voltage is 50 V. The armature resistance of the drive is measured to be 0.012 12. The effects of armature reaction may be assumed to be negligible. a) Calculate the armature current, input power, mechanical power and torque when the terminal voltage is 55 Volts. b) Calculate the armature current, input power, mechanical power, and torque when the terminal voltage is 44 Volts. c) The drive design is now modified to include a variable resistance (Rv), in series with the armature, increasing the overall armature resistance. Ry has a range between 0.01 12 (minimum) to 0.1 12 (maximum). If the terminal voltage is 60V, calculate new range (maximum and minimum values) of armature current, input power, mechanical power and torque with the variable resistance added. d) State whether the drive is operating as a motor or a generator for this operating condition. Give reasons for your answer. Suggest an application for the new design.

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Transcribed Image Text: A 25 kW, 50 V separately excited DC drive is operated at a constant speed of 3000 rpm with a constant field current such that the open-circuit armature voltage is 50 V. The armature resistance of the drive is measured to be 0.012 12. The effects of armature reaction may be assumed to be negligible. a) Calculate the armature current, input power, mechanical power and torque when the terminal voltage is 55 Volts. b) Calculate the armature current, input power, mechanical power, and torque when the terminal voltage is 44 Volts. c) The drive design is now modified to include a variable resistance (Rv), in series with the armature, increasing the overall armature resistance. Ry has a range between 0.01 12 (minimum) to 0.1 12 (maximum). If the terminal voltage is 60V, calculate new range (maximum and minimum values) of armature current, input power, mechanical power and torque with the variable resistance added. d) State whether the drive is operating as a motor or a generator for this operating condition. Give reasons for your answer. Suggest an application for the new design.
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Transcribed Image Text: A 25 kW, 50 V separately excited DC drive is operated at a constant speed of 3000 rpm with a constant field current such that the open-circuit armature voltage is 50 V. The armature resistance of the drive is measured to be 0.012 12. The effects of armature reaction may be assumed to be negligible. a) Calculate the armature current, input power, mechanical power and torque when the terminal voltage is 55 Volts. b) Calculate the armature current, input power, mechanical power, and torque when the terminal voltage is 44 Volts. c) The drive design is now modified to include a variable resistance (Rv), in series with the armature, increasing the overall armature resistance. Ry has a range between 0.01 12 (minimum) to 0.1 12 (maximum). If the terminal voltage is 60V, calculate new range (maximum and minimum values) of armature current, input power, mechanical power and torque with the variable resistance added. d) State whether the drive is operating as a motor or a generator for this operating condition. Give reasons for your answer. Suggest an application for the new design.
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Given data,(1)Separately excited DC Dóve 25kw,50V" Speed "(N)=3000" rpm "If E > V=> machine acts as generatolE < V=> machine acts as motor.a){:[" Terminal voltage "{:(V_(t))=55(V)}∈<V=>" Drive acts as motor. "],[k=50V],[" Ra "],[V_(t)=E+I_(a)R_(a)],[T_(a)=(V_(t)-E)/(R_(a))=(55-50)/(0.012)=416.67A],[I_(a)=416.67A],[" Armature current "],[rarr" Input power "(f_(in))=V_(t).I_(a)=55 xx416.67=22916.85WquadP_("in ")=22916.85w],[rarr" mechanical power dweloped "(P_(m))=E_(b)*T_(a)=50 xx416.67=20883.5WquadP_(m)=20883.5W]:}rarr" Torque dweloped "(T)=(P_(m))/(omega)quad;quad omega=(2pi N)/(60)=(2pi xx3000)/(60)=314.16rad//sScanned with CamScannerT=(20883.5)/(314.16)=66.47N-mquad T=66.47Nm(2)(b) Terminal voltage {:[(V_(t)),=44V],[epsi,=50V]}E > V=> machine ats as generctor{:[rarr" mechanicaf poower deculoped "(P_(n))=E*I_(a)],[" Armature current "(I_(e))=500A],[P_(n)=50 xx500=25000WquadP_(m)=25kW],[rarr" Outsut town "(P_("out "))=v_(t)*" I "_(a)=44 xx500=22000wquadP_("out ")=22kw],[rarr" Torque dealopen "(T)=(P_(m))/(omega)=(25000)/(314.16)=79.57Nmquad T=79.57Nm]:}(c) Te ... See the full answer