IF A CAR AHEAD OF YOU HAS STOPPED AT A CROSSWALK, YOU SHOULD:

Two balanced Y-connected loads in parallel, one drawing 15kW at 0.6 power factor lagging and the other drawing 10kVA at 0.8 powe

NemiM [27]

Answer:

(a) attached below

(b) $pf_{C}=0.85$ $lagging$

(c) $I_{C} =32.37 A$

(d) $X_{C} =49.37$ Ω

(e) $I_{cap} =9.72 A$ and $I_{line} =27.66 A$

Explanation:

Given data:

$P_{1}=15 kW$

$S_{2} =10 kVA$

$pf_{1} =0.6$ $lagging$

$pf_{2}=0.8$ $leading$

$V=480$ $Volts$

(a) Draw the power triangle for each load and for the combined load.

$\alpha_{1}=cos^{-1} (0.6)=53.13$ °

$\alpha_{2}=cos^{-1} (0.8)=36.86$ °

$S_{1}=P_{1} /pf_{1} =15/0.6=25 kVA$

$Q_{1}=P_{1} tan(\alpha_{1} )=15*tan(53.13)=19.99$ ≅ $20kVAR$

$P_{2} =S_{2}*pf_{2} =10*0.8=8 kW$

$Q_{2} =P_{2} tan(\alpha_{2} )=8*tan(-36.86)=-5.99$ ≅ $-6 kVAR$

The negative sign means that the load 2 is providing reactive power rather than consuming

Then the combined load will be

$P_{c} =P_{1} +P_{2} =15+8=23 kW$

$Q_{c} =Q_{1} +Q_{2} =20-6=14 kVAR$

(b) Determine the power factor of the combined load and state whether lagging or leading.

$S_{c} =P_{c} +jQ_{c} =23+14j$

or in the polar form

$S_{c} =26.92$ °

$pf_{C}=cos(31.32) =0.85$ $lagging$

The relationship between Apparent power S and Current I is

$S=VI^{*}$

Since there is conjugate of current I therefore, the angle will become negative and hence power factor will be lagging.

(c) Determine the magnitude of the line current from the source.

Current of the combined load can be found by

$I_{C} =S_{C}/\sqrt{3}*V$

$I_{C} =26.92*10^3/\sqrt{3}*480=32.37 A$

(d) Δ-connected capacitors are now installed in parallel with the combined load. What value of capacitive reactance is needed in each leg of the A to make the source power factor unity?Give your answer in Ω

$Q_{C} =3*V^2/X_{C}$

$X_{C} =3*V^2/Q_{C}$

$X_{C} =3*(480)^2/14*10^3$ Ω

(e) Compute the magnitude of the current in each capacitor and the line current from the source.

Current flowing in the capacitor is

$I_{cap} =V/X_{C} =480/49.37=9.72 A$

Line current flowing from the source is

$I_{line} =P_{C} /3*V=23*10^3/3*480=27.66 A$

8 0

3 years ago

1. Which of the following is NOT an example of a lever?

Umnica [9.8K]

A staircase what makes it a lever is another objects used to displace the force better

8 0

4 years ago

How to make a shopping cart move with ease without a motor. Like if the carts front wheels were smaller than the ones in the bac

Anastasy [175]

Answer:give the cart another shape

Explanation:an aeroplane shape makes it fast,,in physical science,the streamlined body makes a body fast

3 0

4 years ago

Help please all of the numbers b4 the equal sign are wrong

Nostrana [21]

Answer:

3/5" = 12'
1 3/4" = 35'
1 1/4" = 25'
9/10" = 18'
2 13/20" = 53'

Explanation:

One number is wrong; they all lack units.

The basic ratio is 1" = 20', so you can divide feet by 20 to find inches.

3/5" = 12'
1 3/4" = 35'
1 1/4" = 25'
9/10" = 18'
2 13/20" = 53'

Perhaps you want decimal inches:

0.60" = 12'
1.75" = 35'
1.25" = 25'
0.90" = 18'
2.65" = 53'

7 0

3 years ago

A farmer wants to buy a 10 kg bag of fertilizer (organic soil). They have the choice between two merchants. Merchant A sells the

sergejj [24]

Answer:

Since the farmer wants to buy a 10 kg bag of fertilizer, he should buy it from merchant A. However, Merchant A and B are selling at the same price for a unit value. In other words, Both Merchant A and B are selling 1kg of dry fertilizer for $1.

Explanation:

Which merchant has the better deal means which merchant offers the farmer a better deal.

For Merchant A, 10 kg bag = $10

meaning it contains a real 10 kg bag of dry fertilizer which the farmer can use without losing any Kg to drying.

While for Merchant B, 10 kg bag = $8

where the 10kg = 80% dry fertilizer + 20% water content

But the farmer can only use the solid constituents of the bag which means,

Merchant B is giving 80/100 x 10Kg of dry fertilizer for $8

That is, 8kg for $8

Since the farmer wants to buy a 10 kg bag of fertilizer, he should buy it from merchant A. However, Merchant A and B are selling at the same price for a unit value. In other words, Both Merchant A and B are selling 1kg of dry fertilizer for $1.

5 0

3 years ago