Question

*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 showing Bnet, Br, Bs, IA, ? and ?

Answer #1

Please be clear in conceot and handwriting, thank
you.
A 20 kVA three-phase synchronous machine is connected to a 480
V, 60 Hz electrical service.
The per-phase armature reactance is 80%. Armature resistance is
negligible, as are all other sources of power loss.
Part A: Motor Configuration
The machine is configured to run as a motor. Its rated mechanical
power is 20 HP and it is 94% efficient.
The motor provides rated output mechanical power.
The excitation is set such...

A three-phase Wye-connected synchronous generator is rated 3600
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XS is 0.25Ω. The rotational losses are 6kW, the core
losses are 4kW, and the stray losses are 1% of the output real
power. The generator is delivering 200kVA power at 0.85 pf lagging
at rated voltage. Taking the phase voltage at the output as a
reference, answer the following questions.
How many poles...

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threephase delta-wye connected step-down transformer that is
constructed from three individual single-phase transformers. Each
the single-phase transformers has rated power of 200 kVA has a
turns ratio of 4:1 where the rated primary voltage of 8.0 kV and a
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(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,...

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...

A 3- phase, 2 pole Y-connected synchronous machines has a
line-line voltage of 6,000V in 60Hz power line, has an armature
reactance of 2ohms/ phase and negligible armature resistance.
Compute the following
A) In case of generating action if the line current is 385 A at
a leading power factor of 0.8, the armature voltage per phase is
3464V, Compute the voltage per phase and power angle.
B) Draw the phasor diagram.
C) If the losses in the machine is...

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 three-phase, 9,375 kVA, 13.8 kV, 4-pole, 60 Hz, Y-connected
synchronous generator has a synchronous reactance, Xs = 17.9, and
is connected to an infinite bus at rated voltage. If the rotational
and electrical losses are negligivle, what is Ia, Ef, delta, theta,
Tdrive, Phasor diagram, and power flow diagram (label completely
with numerical values for,
A) the machine as a generator; the prime-throttle is opened and
If is adjusted so that the machine delivers rated kVA, 0.8 pf
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A 20kW. 3-phase, +40 V. 4 pole, delta-connected permanent magnet
synchronous motor has following parameters Xs=5 ohm, Rs
negligible rated power factor = 1.0. Machine is
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Calculate
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load torque and 750 rpm.
(ii) armature current, torque angle and power factor at half
full load torque and 1000 rpm.
(iii) The braking torque, torque angle and power factor when
working under...

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