Question

1. A dc motor connected to a 240 V line produces a mechanical output of 160 hp.Knowing that the losses are 12 kW, calculate the input power and the line current.

2. An electric motor driving a skip hoist withdraws 1.5 metric tons of minerals from a trench 20 m deep every 30 seconds. If the hoist has an overall efficiency of 94 percent, calculate the power output of the motor in horsepower and in kilowatts.

Answer #1

A 200 V DC, 1,800 RPM shunt connected motor has an armature
resistance of 0.4 ohm and a brush resistance of 0.4 ohm; brush
voltage drop of 6.0 V, independent of load. The resistance of the
shunt field is 230 ohm. The full load rated line current is 40 A.
When the motor is operated at no load the line current is 5 A and
the speed is 1750 RPM.
Calculate speed at rated load
Calculate speed at .3 rated...

A 208 V 10 Hp four pole 60 Hz Y connected induction motor has a
full load slip of 5%.
What is the output power of this motor in kW?
If friction and windage loss is 350 watts, what is the gross
mechanical output at full
load?
What is the gross torque of this motor at full load?
What is the rotor cupper loss at full load?
If the efficiency of this motor is 90% at full load what is...

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