Question

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 load.

Find power to coupling field at rated load

Find torque to mechanical load of motor at rated conditions

Find electrical power of motor at rated load

Find efficiency of motor at rated load

Find percent speed regulation of motor from no-load to full load

If the machine was driven by a generator, what speed must the shaft be turned to have 200 VDC at rated current 40A.

Find effeciency of generator at rated load

Find drive torque of generator at rated load.

Answer #1

A 100 hp, 250 V, 1200 rpm DC shunt motor
with an armature resistance of 0.03 ? and a field
resistance of 41.67 ?. The motor has compensating
windings, so armature reactance can be ignored.
Mechanical and core losses may be ignored also. The
motor is driving a load with a line current of 126 A and
an initial speed of 1103 rpm. The magnetization curve is
shown in the following figure.
1. What is the motor speed if the...

A 230-V DC shunt motor has armature circuit resistance of 0.25 ?
and field circuit resistance of 115 ?. At
full load armature draws a current of 38 A and the speed is
measured at 1050 rpm. Find the developed
torque.
The field rheostat is now changed so that total field resistance is
144 ?. Find the speed under this condition.
Assume that the armature current does not change. Assuming the
rotational losses amount to 600 W, find the
efficiency...

The full-load armature current of a 5 hp, 150 V shunt dc motor
is 30 A. The field (shunt) resistance and the armature resistance
of the motor are ????F = 125 ? and ???????? = 0.15, respectively.
At a random speed of 1800 rpm magnetization curve of the motor has
measured and is shown in the table below. ????0 (V) armature
voltage 10 90 110 140 170 185 ???????? (A) field (shunt) current 0
0.82 1 1.2 1.7 2.88 Calculate...

Question 2
The full-load armature current of a 5 hp, 150 V shunt dc motor
is 30 A. The field (shunt) resistance and the armature resistance
of the motor are ????F=125 ? and ????????=0.15, respectively. At a
random speed of 1800 rpm magnetization curve of the motor has
measured and is shown in the table below.
EO(V) armature voltage
10
90
110
140
170
185
IF (A) field (shunt) current
0
0.82
1
1.2
1.7
2.88
Calculate the following:
a....

A 152 V DC shunt motor has an armature resistance of 0.3ohm, a
brush voltage drop of 2 V, the rated full load current is 70 A.
A) calculate the current at the instant of starting as a
percentage of full load current
B) calculate the value of starting resistance of limit the motor
current at the instant of starting to 150 percent of the rated load
current

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...

A 60 kW, 400 V d.c. shunt motor has 4 poles a
2-circuit wave-connected armature winding with
450 conductors. The flux per pole is 45 mWb. The full-load
efficiency of the motor is 90.5%. The
armature and interpole windings have a total resistance of 0.1 Ω.
The shunt field resistance is
200 Ω. Calculate (i) the line current (ii) full-load speed and
(iii) armature torque.

a)Explain the shunt excitation and compound excitation of DC
generator.
b)A 240V compound DC motor has the armature, series field and
shunt field resistances are
0.22 Ω, 0.04 Ω and 200 Ω respectively. On full load, the line
current is 17.5 A and the motor runs at 1800 rpm. (short
shunt)
i) Draw the diagram and the power flow of the motor.
ii) Find the back EMF of the motor.
iii) Find the mechanical power developed.
iv) Find the output...

A 25-hp, 240V, DC shunt motor has
armature and field resistances of 0.2 ? and 120 ?, respectively. At
no load and rated voltage, the motor draws a line current of 5A and
its speed is 1250 rpm.
When driving a certain load, the
input to the motor is 15KW. For this condition, find:
a.The speed of the motor
b.The developed torque
The efficiency of the motor at this load

An 800 rpm, 500 V, 120 A (armature current), series
motor has a field resistance of 0,04 Ω and an armature resistance
of 0.11 Ω. Determine the speed of the motor: 2.1 For a supply
voltage of 550 V and a current of 60 A. (9) 2.2 For a torque of 50%
of full-load, a supply voltage of 500 V and a diverter across the
field of 0.08 Ω. (11) 2.3 With a resistance of 1 Ω in series with...

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