a) Draw the armature and excitation circuit of the motor and write the formulas for the equivalent circuit. b) If the load moment of the motor at the nominal armature voltage is 420 Nm, then calculate the armature current and the input power of the motor. c) If the armature voltage of the motor is kept constant at 600 V and the excitation current is decreased until the speed reaches 4000 rpm, then calculate the shaft moment. Show this working area on the M = f (W) axis.
The armature circuit of a free excited direct current motor with a nominal voltage of 600 V is fed from an adjusted direct voltage source. The excitation circuit is also powered from a regulated voltage source. It is used in an application that requires motor speed adjustment. The speed of the motor at the nominal armature voltage was measured as 1600 rpm. All losses of the motor and voltage source and the effect of armature reaction are neglected. It is accepted that the engine is not saturated.
Answer the questions below.
a) Draw the armature and excitation circuit of the motor and write the formulas for the equivalent circuit.
b) If the load moment of the motor at the nominal armature voltage is 420 Nm, then calculate the armature current and the input power of the motor.
c) If the armature voltage of the motor is kept constant at 600 V and the excitation current is decreased until the speed reaches 4000 rpm, then calculate the shaft moment. Show this working area on the M = f (W) axis.
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