1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
den301095 [7]
3 years ago
15

An inverse-time circuit breaker (CB) is used for branch-circuit short-circuit and ground-fault protection for a 30-horsepower, 2

08-volt, 3-phase squirrel-cage motor. Calculate the maximum rating permitted for the circuit breaker.
Physics
1 answer:
Maru [420]3 years ago
3 0

Answer:

Explanation:

Motor rating is given in horsepower (hp), it will be converted in watt (W).

Standard to install circuit breaker for an electric circuit is usually 20% ~ 25% more than the Rated Current of the circuit

while

Standard to install overload relay for an electric circuit is usually 20% ~ 25% more than the Running Current of the circuit.

So, to find the maximum capacity of the circuit breaker, rated current of the motor will be multiplied by 1.2 ~ 1.25

Step by Step Explanation:

30hp = 22371W (as 1hp = 745.7)

Assuming unity power factor (cosФ=1) and 208V phase to phase voltage:

Rated Power (watt) = √3 . V.I. cosФ

<em>{if 208V is phase to neutral voltage, then use following formula:</em>

<em> Rated Power (watt) = 3 . V.I. cosФ}</em>

\frac{22371}{\sqrt{3} * 208 * 1} = I

Rated Current = <u>62.169A</u>

So, required maximum rating for circuit breaker is:

20% to 25% of the rated current = 62.17*1.2 ~ 62.17*1.25

=74.6A ~ 77.7A

Hence, any breaker between the above mentioned rating will be appropriate.

You might be interested in
If a system has 225 kcal of work done to it, and releases 5.00 × 102 kj of heat into its surroundings, what is the change in int
vovikov84 [41]

We can solve the problem by using the first law of thermodynamics:

\Delta U = Q-W

where

\Delta U is the change in internal energy of the system

Q is the heat absorbed by the system

W is the work done by the system on the surrounding


In this problem, the work done by the system is

W=-225 kcal=-941.4 kJ

with a negative sign because the work is done by the surrounding on the system, while the heat absorbed is

Q=-5 \cdot 10^2 kJ=-500 kJ

with a negative sign as well because it is released by the system.


Therefore, by using the initial equation, we find

\Delta U=Q-W=-500 kJ+941.4 kJ=441.4 kJ

8 0
3 years ago
Which statement best describes how light behaves with liquids, gases, and solids?
juin [17]

Answer:

C number is write i think

3 0
2 years ago
In order to be considered a semi-conductor the material must
wel
First one, for instance they become conductors or insulators depending on the temperature!
4 0
3 years ago
Read 2 more answers
Which one of the following energy conversion devices has the lowest energy efficiency?
Anna35 [415]

Answer:

A) incandescent ligth bulb, its efficiency is about 10%

Explanation:

The incandescent bulb, that is, the well-known focus with its warm light, was one of the most useful inventions of the 19th century although its use is currently considered very inefficient. These lamps waste between 80 and 90 percent of the total electricity they consume by turning it into heat. The metal filament thus heated and which is the central part of the bulb, only converts the remaining energy into light. Its service life ranges from 750 to 1,000 hours.

This is why they are used in ovens for food preparation, because of the large amount of heat they generate.

The steam boiler in a power plant depends on the fuel that it is using, but a coal-fired power plant with modern technology its efficiency is about 40%

Electric motor are around 85-92%

In order to better understand the concept of efficiency it is as if we pay 100 dollars of gasoline for our weekly use, but of that 100 dollars the car only uses 10 dollars to do that activity the rest of the money the 90 dollars were lost because of the inefficiencies of the vehicle.

3 0
3 years ago
how much heat is required to raise the temperature 500 of song of iron from 50°to 250°c? (take c=480j/kg°c)​
Mars2501 [29]

Answer:

Explanation:

523 degrees

5 0
2 years ago
Other questions:
  • The volume of a liquid is often given in
    7·1 answer
  • Why is heat acclimatization important?
    14·1 answer
  • A driver of a car traveling at 15.0 m/s applies the brakes, causing a uni- form acceleration of −2.0 m/s2 . How long does it tak
    6·1 answer
  • 2.<br> The inertia of an object depends on its
    12·1 answer
  • If speed quadruples from 11 m/s to 44 m/s, what happens to the kinetic energy?
    14·1 answer
  • An ice skater accelerates backwards for 5.0 seconds to a final speed of 12 m/s. If the acceleration backwards was at a rate of 1
    8·1 answer
  • HELPPPPPPPPPPPPPPPPPPPPPPPPPP
    8·1 answer
  • How could you increase the sliding friction between the sled and track? How could you decrease it?​
    12·2 answers
  • . An experimental rocket plane lands on skids on a dry lake bed. If it’s traveling at 80.0 m/s when it touches down, how far doe
    12·1 answer
  • Which has more mass - a 5-kg bag of feathers or a 5-kg<br> cannon ball?
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!