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UNO [17]
3 years ago
6

A three-phase, Y-connected, 75MVA, 27kV synchronous generator has a synchronous reactance of 9.0/phase. Using rated MVA and volt

age as the base values, determine the per-unit reactance. Then refer this per-unit value to a 100-MVA, 30kV base.
Engineering
1 answer:
Tatiana [17]3 years ago
3 0

Given Information:  

ZΩ = 9 per phase

Sbase = 75 MVA

Sbase = 100 MVA

kV = 27 kV

kV = 30 kV

Required Information:  

Zpu = ?

Zpu_new = ?

Answer:  

Zpu = 0.925 pu

Zpu_new = 1 pu

Explanation:  

Zbase = (kVbase)²/Sbase

Zbase = (27x10³)²/75x10⁶

Zbase = 9.72

Zpu = Zactual/Zbase

Zpu = 9/9.72

Zpu = 0.925 pu

Now base MVA is changed to 100 MVA and base kV is changed to 30kV so the per unit value becomes

Zbase = (kVbase)²/Sbase

Zbase = (30x10³)²/100x10⁶

Zbase = 9

Zpu_new = Zactual/Zbase

Zpu_new = 9/9

Zpu_new = 1 pu

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Viefleur [7K]

Answer:

The flow of a real fluid has <u>more</u> complexity as compared to an ideal fluid owing to the phenomena caused by existence of <u>viscosity</u>

Explanation:

For a ideal fluid we know that there is no viscosity of the fluid hence the boundary condition need's not to be satisfied and the flow occur's without any head loss due to viscous nature of the fluid. The friction of the pipe has no effect on the flow of an ideal fluid. But for a real fluid the viscosity of the fluid has a non zero value, the viscosity causes boundary layer effects, causes head loss and also frictional losses due to pipe friction hugely make the analysis of the flow complex. The losses in the energy of the flow becomes complex to calculate as frictional losses depend on the roughness of the pipe and Reynolds number of the flow thus increasing the complexity of the analysis of flow.

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3 years ago
What is A roofed structure that is similar to a porch, but is detached from the house.
agasfer [191]

Answer:

a gazebo

Explanation:

6 0
4 years ago
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A projectile is launched vertically with a velocity of 30 mxs . How long will it take to return to the original launch position?
rewona [7]

Answer: If the projectile is launched vertically, then you only aply velocity on the y axis.

The velocity 30 m/s is the initial velocity and if it is fired on the ground, then the initial position is 0m (this doesn't really matter), and now, let's analyze the forces on the projectile.

Once it is fired, the only force acting on the projectile is the force of gravity, and we know that the gravity acceleration is -g =  -9.8\frac{m}{s^{2} }, where the negative sign is there because this acceleration points downward.

so A(t) =  -9.8\frac{m}{s^{2} }

For the velocity, we need to integrate the acceleration in the time, this is:

v(t) = -9.8\frac{m}{s^{2} }*t + v0

where v0 is the initial velocity, in this case 30m/s

And for the position, we need to integrate again, so:

r(t) = -4.9\frac{m}{s^{2} }*t^{2}  + 30\frac{m}{s} *t + r0

where r0 is the initial position, in this case 0m.

now the question is "How long will it take to return to the original launch position?"

So now we need to find the time in which r(t) is zero again (so the projectile is in the ground again

so r(t) = 0 = r(t) = -4.9\frac{m}{s^{2} }*t^{2}  + 30\frac{m}{s} *t + r0

this is: r(t) =  t*(-4.9*t + 30) = 0

so is easy to see that t = 0 (because it is fired in the ground) is a solution, but is not the one that we are looking for,

so we only look inside the parentheses:

-4.9*t + 30 = 0

t = 30/4.9 = 6.12 s

So 6.12 seconds after the projectile is fired, it returns to the ground, or the original launch position.

6 0
4 years ago
If a light draws 220 watts on a 120 volt circuit, how many amperes of electricity is it using?
vazorg [7]

Answer:

About 1.84 amperes

Explanation:

Since calculating amperes is dividing w/v, we can divided 220 by 120.

220/120 = 1.83333333333

Which can be rounded to:

1.84

8 0
3 years ago
The output side of an ideal transformer has 35 turns, and supplies 2.0 A to a 24-W device. Ifthe input is a standard wall outlet
Crank

Answer:

The current drawn from the outlet is 0.2 A

The number of turns on the input side is 350 turns

Explanation:

Given;

number of turns of the secondary coil, Ns = 35 turns

the output current, I_s = 2 A

power supplied, P_s = 24 W

the standard wall outlet in most homes = 120 V = input voltage

For an ideal transformer; output power = input power

the current drawn from the outlet is calculated;

I_pV_p = P_s\\\\I_p = \frac{P_s}{V_p} = \frac{24}{120} = 0.2 \ A

The number of turns on the input side is calculated as;

\frac{N_p}{N_s} = \frac{I_s}{I_p}  \\\\N_p = \frac{N_sI_s}{I_p} \\\\N_p = \frac{35 \times 2}{0.2} \\\\N_p = 350 \ turns

4 0
3 years ago
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