Question

**A 230 V, 250 rpm, 100 A separately excited dc motor has
an armature resistance of 0.5 Ω. The motor is connected to 230 V dc
supply and rated dc voltage is applied the field winding. It is
driving a load whose torque-speed characteristic is given
by**

**TL = 500 − 10ω where ω is the speed in rad/sec and TL is
the load torque in N-m. Find**

**(a) the steady state speed at which the motor will drive
the load. (b) the armature current.**

**Neglect the rotational losses of the
machine.**

Answer #1

A 220 V, 960 rpm, 20 A separately excited DC motor has
armature resistance and inductance of 1.2 ohms and 50 mH
respectively. Motor is controlled by a single phase half controlled
rectifier with source voltage of 230 V, 50Hz.
(a) Calculate no load speeds and speeds and developed torques on
the boundary between continuous and discontinuous conduction for ą
= 45°, 90° and 135°.
(b) Calculate and plot speed torque curve for ą = 45°.

A separately excited DC motor has the following parameters:
field resistance = 250 ?, armature resistance = 0.03 ?, terminal
voltage = 250 V and field voltage = 250 V. Initially the machine
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dropped to 50% of its original value, b) find the speed of the
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A separate excited DC motor is running at 1000 rpm when the
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i. Calculate the value of the resistance of the dynamic braking at
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ii. If the motor operates in regenerative braking at a speed of
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A 200 V DC, 1,800 RPM shunt connected motor has an armature
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When the motor is operated at no load the line current is 5 A and
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Calculate speed at rated load
Calculate speed at .3 rated...

A 100 hp, 250 V, 1200 rpm DC shunt motor
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Mechanical and core losses may be ignored also. The
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A 230-V DC shunt motor has armature circuit resistance of 0.25 ?
and field circuit resistance of 115 ?. At
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The field rheostat is now changed so that total field resistance is
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Assume that the armature current does not change. Assuming the
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An 800 rpm, 500 V, 120 A (armature current), series
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A 210 V, 1200 rpm, 10 A separately excited motor is controlled
by 1-
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V,
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any
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ii....

A 25-hp, 240V, DC shunt motor has
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When driving a certain load, the
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The full-load armature current of a 5 hp, 150 V shunt dc motor
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