Question

1.
A single phase circuit has a load of 500kVa at a power factor of
0.707 lagging. Calculate the kVA of the capacitors needed to
improve the power factor to unity

3. When connected to a 120-v(rms), 60Hz power line, a load
absorbes 4 kw at a lagging power factor of 0.8. Find the
capacitance necessary to raise the pf to 0.9

4. A three phase motor draws 20kva at 0.707 power factor
lagging from a 208V source. Determine the kVa rating of the
capacitors to make the combined power factor 0.9 lagging and
determine the line current before and after the capacitors are
added.

Answer #1

A single-phase motor takes 8.3 A at a power factor of 0.866
lagging when connected to a 230 V, 50 Hz supply. Two similar
capacitors are connected in parallel with each other to form a
capacitance bank. This capacitance bank is now connected in
parallel with the motor to raise the power factor to unity.
Determine the capacitance of each capacitor

THESE ARE QUESTION FROM THE TOPIC POWER FACTOR IMPROVEMENT FROM
THE SUBJECT POWER SYSTEM FUNDAMENTALS PLEASE DO THE QUESTIONS STEP
BY STEP AND IN NEAT HAND WRITTING THE ANSWERS ARE GIVEN WITH THE
QUESTIONS
1) 1. What should be the kVA rating of a capacitor which would
raise the power factor of load of 100 kW from 0·5 lagging to 0·9
lagging
ANS (125 KVA)
2) A 3-phase, 50 Hz, 3300 V star connected
induction motor develops 250 H.P....

A 3 phase, 3.3 kV industrial plant has an overall power factor
of 0.88 lagging. A 200 kVA synchronous motor is added to the system
and is run at zero power
factor and slightly reduced rating to provide power factor
correction only. The total load is then 350 kVA at unity power
factor. It was then decided to run the synchronous machine at its
rated kVA and use it as a source of mechanical power, what gross
mechanical power would...

A 15kw single phase load connected to an alternator at 230v and
a power factor of 0.6lag. Determine
?minimum alternator rating, current carrying capacity of the
cables, minimum kVA rating of capacitor bank to increase power
factor to 0.8

Electrical Circuit
A) A factory (with frequency 60 HZ)
has the following electrical loads:
Induction motors
of 16 kW at a lagging power factor of 0.8.
Induction motors
of 20 kW at a lagging power factor of 0.7.
Load of 12 KVA at a lagging factor
of 0.9. Load of 10 KVAR at a leading factor of 0.8
a-what is the overall power factor
of the factory.
b- Assume that the voltage at the
input to the factory is 440...

A single-phase load consumes 10kW at 0.9 power factor, power
factor lagging at 220V.What is the magnitude and phase angle of
current drawn from the source? If another single-phase load rated
at 10kW and 0.8 leading power factor is connected in parallel to
the sources, what is the magnitude of the current drawn? What is
the current drawn from Source? Give your answer in polar form.

A
motor draws 12A rms from 210 V rms, a 60 hz ac source at 0.85 pf
lagging. If a capacitor is connected to make the power factor
unity, the approximate capacitance of the capacitor will be:

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...

Two AC loads connected in parallel draw power from a 60 Hz,
120-Vrms source. Load 1 draws 350 W at a lagging power factor of
0.7. Load 2 draws 500 VA at a leading power factor of 0.5. a. (5)
Calculate the effective (rms magnitude) current drawn by load 1. b.
(10) Calculate the impedance of Load 1. c. (5) Calculate the total
complex power drawn by both loads combined. d. (5) Determine the PF
of the combined load. Specify...

A 10-kVA, 250 / 100-V, 50-Hz single-phase transformer gave the
following open and short circuit test results:
Open circuit test: 250 V, 2.6 A, power factor: 0.3 on HV
side.
Short circuit test: 18 V, 80 A, input power: 240 W on HV
side.
Calculate the following:
4.1 The equivalent circuit parameters of the transformer. (6)
4.2 The efficiency at full load unity power factor. (NB the test
current is not at full load) (6)
4.3 The load at which...

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