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Alecsey [184]
3 years ago
6

Question 5 (20 pts) The rated current of a three-phase transmission line is 300 A. The currents flowing by the line are measured

with three current transformers each with ratio 250 : 5. What is the current you would measure at the secondary of each current transformer if rated current is flowing through each line. (of course the secondaries of the transformer must be part of closed circuits.) Consider the measured currents are exciting three over-current relays. Should the contacts of the relay close if rated current is circulating in the lines? If your answer is between no and yes, the current that the relay observes when rated current flows by the line must be the minimum pick-up current Ip. Hence, the tap position you should select, e.g., in the tap block of Fig. 1, must be equal o slightly greater than Ip for an over-current relay. Slightly greater when Ip is not an integer that matches the tap selection.
Engineering
1 answer:
prisoha [69]3 years ago
3 0

Answer:

Check the explanation

Explanation:

Question 1.

The secondary current of 250/5 amps CT when 300 amps(rated current of transmission line ) flow in TL is

(5/250 ) X 300 = 6 amps

Question 2

The correct answer to this second question is yes, when Over current relay coil will operate and relay contacts gets close, if the pickup value( Ip) of relay is set as 6 amps in relay. ( because primary current of TL is 1.2 times of CT primary)

Question 3

Tap Block figure (Fig 1) is not available/uploaded in your question.

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2 years ago
Read 2 more answers
Water steam enters a turbine at a temperature of 400 o C and a pressure of 3 MPa. Water saturated vapor exhausts from the turbin
yulyashka [42]

Answer:

a) -505.229 kJ/Kg

b) -1.724 kJ/kg

Explanation:

T1 = 400°C

P1 = 3 MPa

P2 = 125 kPa

work output   = 530 kJ/kg

surrounding temperature = 20°C = 293 k

<u>A) Calculate heat transfer from Turbine to surroundings </u>

Q = h2 + w - h1

h ( enthalpy )

h1 = 3231.229 kj/kg

enthalpy at P2

h2 = hg = 2676 kj/kg

back to equation 1

Q = 2676 + 50 - 3231.229  = -505.229 kJ/Kg  ( i.e.  heat is lost )

<u>b) Entropy generation </u>

entropy generation = Δs ( surrounding )  + Δs(system)

                                =  - 505.229 / 293   + 0

                                = -1.724 kJ/kg  

6 0
2 years ago
How do performance expectation change over time for a technology?
dusya [7]

Answer:

The digitization of performance management not only provides more precise data but also positively influences management processes and strategic development. Technology-enabled performance management tools simplify the manager's evaluation process and turn employees into active participants in their review sessions

4 0
3 years ago
Consider an adiabatic throttling valve with water entering at pressure of 1.5 MPa, a temperature of 150°C and a velocity of 4.5
Marta_Voda [28]

Answer:

So the exit velocity of water is 4.5 m/s

Explanation:

Given that

Water entering pressure = 1.5 MPa

Temperature = 150°C

Velocity = 4.5 m/s

From first law of thermodynamics for open system

h_1+\dfrac{V_1^2}{2}+Q=h_2+\dfrac{V_2^2}{2}+W

Here given that valve is adiabatic so Q= 0

In valve W= 0

Wen also also know that throttling process is an constant enthaply process so

h_1=h_2

h_1+\dfrac{V_1^2}{2}+Q=h_2+\dfrac{V_2^2}{2}+W

h_1+\dfrac{V_1^2}{2}+0=h_1+\dfrac{V_2^2}{2}+0

So from above equation we can say that

V_2=V_1

So the exit velocity of water is 4.5 m/s

5 0
2 years ago
You wish to design a cantilever beam with a square cross section and length L that can support an end load of F without yielding
koban [17]

Answer:

with a square cross section and length L that can support an end load of F without yielding. You also wish to minimize the amount the beam deflects under load. What is the free variable(s) (other than the material) for this design problem?

a. End load, F.

b. Length, L.

c. Beam thickness, b

d. Deflection, δ

e. Answers b and c.

f. All of the above.

8 0
3 years ago
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