Question

410 Volt, 60 Hz, 600 hp, 0.6 pf-leading, four-pole Triangle connected synchronous motor has 0.9Ω synchronous reactance. Friction; wind; core losses and armature resistance are neglected.

a) If the motor is operating under magnitude of phase current (ia) 230 Ampere and power factor of 0.6 lagging,

1. Find the input power of motor in hp (10p)

2. Find the generated voltage, EA (10p)

3. Find the torque and the maximum inducible torque in current state. (10p)

b) If EA is increased by 18% find,

1. Magnitude of new armature current (ia), (10p)

2. New power factor of motor. (10p)

Answer #1

(360) Volt, 60 Hz, 600 hp, 0.6 pf-leading, four-pole -connected
synchronous motor has 0.9Ω synchronous reactance. Friction; wind;
core losses and armature resistance are neglected.
a) If the motor is operating under magnitude of phase current
(ia) (180)
Ampere and power factor of 0.6 lagging,
1. Find the input power of motor in hp
2. Find the generated voltage, EA
3. Find the torque and the maximum inducible torque in current
state.
b) If EA is increased by 18% find,...

The 400 V, 50 kVA, 0.8 power factor leading delta connected
synchronous motor has synchronous reactance of 3-ohm, resistance
neglected. It is supplying a 12-kW load with initial power factor
of 0.86 lagging. The windage and friction losses are 2.0 kW and the
core losses are 1.5 kW. Determine
(a) the motor efficiency; the line current; armature current;
and excitation voltage.
(b) If the flux of the motor is increased by 20 percent
determine the excitation voltage; armature current; and...

a 460-V 100-hp 60-Hz 4 pole Y connected synchronous motor has a
operating power factor 0.85 leading the aramature resistance is o.2
ohms and synchronous reactance is 12 ohms at full load the
efficiency is 85% find the sum of mechanical loss core loss and
stray loss when meachine is operating at full load

Question
A 208 V 10 Hp four pole 60 Hz Y connected induction motor has a
full load slip of 5%.
a)-What is the synchronous speed of this motor?
b)-What is the shaft speed of this motor at full load?
c)-What is the frequency of rotor current at full load?
d)-What is the shaft torque of this motor at full load?
e)-If the efficiency of this motor is 90% at full load what is
the input power
f)-If the efficiency...

Please be clear in concept and handwriting.
A 20HP, three-phase, Wye-connected synchronous motor is
connected to a 277VAC, 60Hz
power supply. At rated conditions, the motor runs at 3600 rpm and
presents a 0.85 lagging
power factor to the power supply. The per-phase armature reactance
is 350m?. Armature
resistance is negligible, as are all other sources of power
loss.
Considering rated conditions,
a. draw a single-phase equivalent circuit showing V?, Ea and IA,
with values.
b. draw a phasor diagram...

A 75-kW, 440-V, 0.8-PF-leading Y-connected synchronous generator
has an armature resistance of 0.22 Ω and a synchronous reactance of
3.0 Ω. Its efficiency at full load is 89% (1 Hp=746 watt).
(a) What is the line current of the generator at rated
conditions?
(b) What is the internal generated voltage EA of this motor at
rated conditions?

3) A three-phase, nozzle, 4-pole cylindrical pole synchronous
generator feeds a 400 Volt, 50Hz conversion center. The synchronous
reactance of the synchronous generator is 0.72 Ove armature
resistance is neglected. The relation between the pole voltage E
'induced in the induction of the synchronous generator and the
excitation current, is selected as E, = 824. In this working
environment of the synchronous generator,
a.) On the consumer screen, find the excitation current (U),
load values, internal phase values, the moment...

A three phase Y connected synchronous motor has negligible
armature resistance and a synchronous reactance of 12 ohm/phase.
The motor takes 12,000kW at a line voltage of 13,200V. If the line
current is adjusted so that the excitation voltage is
9000V/phase:
a. What is the torque angle?
b. At what power factor is the motor operating?
c. What is its armature current?

4) A three-phase synchronous motor of 4000 hp nominal, 13,200 V,
60 Hz, 2 poles, connected in star, operating at 0.84 of power
factor in advance, has an efficiency of 96.5%.
The synchronous reactance per phase is 49.33 Ω:
• Draw the phasor diagram on the grid sheet
• Determine the loading angle
• Determine the load torque

A 3-phase, 1.2 MVA, Y-connected, 6.6 KV, 6-poles, 60 HZ,
synchronous generator has a synchronous reactance of 30W and
negligible resistance. The generator is connected to an infinite
bus at 6.6 KV and 60 Hz.
a)Determine the excitation voltage (Ea) when the machine is
delivering rated power at o.8 PF lagging.
b)The field excitation current is increased by 10% without
changing the power input from the prime mover. Find the stator
current (Ia), the power factor and the reactive power...

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