Question

A 25kW 125-V separately excited DC machine is operated at a constant speed of 3000 rpm with a constant field current such that the open circuit armature voltage is 125V. The armature resistance is 0.02 ?. Compute the armature current, the electromagnetic power and torque when the terminal voltage is a) 128 V, and b) 124 V. In both cases determine whether the machine is operating as a motor or a generator. Note: P_terminal = V_a I_a, P_em = E_back-emf I_a

          A 25kW 125-V separately excited DC machine is operated at a constant speed of 3000 rpm with a constant field current such that the open circuit armature voltage is 125V. The armature resistance is 0.02 ?. Compute the armature current, the electromagnetic power and torque when the terminal voltage is a) 128 V, and b) 124 V. In both cases determine whether the machine is operating as a motor or a generator.
Note: P_terminal = V_a I_a, P_em = E_back-emf I_a

A 25kW 125-V separately excited DC machine is operated at a constant speed of 3000 rpm with a constant field current such that the open circuit armature voltage is 125V. The armature resistance is 0.02 ?. Compute the armature current, the electromagnetic power and torque when the terminal voltage is a) 128 V, and b) 124 V. In both cases determine whether the machine is operating as a motor or a generator.
Note: Pterminal = Va Ia, Pem = Eback-emf Ia

Added by Ricardo S.

University Physics with Modern Physics

Hugh D. Young 14th Edition

Instant Answer

Solved by Expert Adi S

09/06/2023

Step 1

- The DC machine has a power rating of 25 kW and operates at a constant speed of 3000 rpm with a constant field current. - The open circuit armature voltage is 125 V, and the armature resistance is 0.02 Ω. - We need to calculate the armature current (I_a), Show more…

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A 25 kW, 125 V separately excited DC machine is operated at a constant speed of 3000 rpm with a constant field current, such that the open circuit armature voltage is 125 V. The armature resistance is 0.02 ̐. Compute the armature current, the electromagnetic power, and torque when the terminal voltage is a 128 V and b 124 V. In both cases, determine whether the machine is operating as a motor or a generator. Note: P_terminal = V_a I_a, P_em = E_back-emf I_a