Frequent question: What is the optimum number of steps for small and large transformers?

Can the plain walled tanks accommodate the transformer for both large and small outputs?

Explanation: The plain walled tanks are large enough to accommodate the transformer and oil has sufficient surface to keep the temperature rise within limits for small outputs. But the plain walled tanks cannot accommodate the transformers for large outputs.

What is the relationship of the space factor value with the large and small outputs?

What is the relationship of the space factor value with the large and small outputs? Explanation: The space factor is directly proportional to the output. If large output is obtained, space factor is high and vice versa.

What is the range of current density for small and medium power transformer?

What is the range of current density for small and medium power transformers? Explanation: In small and medium power transformers, the lowest value of current density is 1.1. The highest permissible value is 2.3 for small and medium power transformers.

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Why is the stepped core used for the transformer?

Stepped core reduces the area of the core and more of the limb can be utilized for placing the windings. Thus lesser copper (mean turn wise) will be used and cost will reduce. Hence I2R losses can be reduced.

What is the formula for number of tubes?

Solution: The surface area per tube will be: Sa = πDL = π (3/12) (10) ft² = 7.854 ft² – (D – tube diameter in ft). The number of tubes required would thus be: n = 178.7 ft² = 22.7 tubes (23 or 24 tubes).

What is the uses of tank with tubes?

What is the usage of the tanks with tubes? Explanation: Temperature rise in transformers is calculated with plain walled tanks. If the limits is exceeded then the plain walled tank is replaced by tank with tubes.

What is the window space factor kW )?

Window space factor is defined as the ratio of copper area in the window to the area of the window. For a given window area, as the voltage rating of the transformer increases, quantity of insulation in the window increases, area of copper reduces. Thus the window space factor reduces as the voltage increases.

What does the window space factor depend?

The window space factor is defined as the ratio of copper area in the window to total window area. It depends upon the relative amounts of insulation and copper provided, which in turn depends upon the voltage rating and output of transformers.

How do you calculate the window space factor of a transformer?

The Correct Formula for Transformer Window space factor kW is:

  1. kW = 50/(30 + kVhv)
  2. kW = 10/(30 + kVhv)
  3. kW = 10/(30 – kVhv)
  4. kW = 50/(30 – kVhv)
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What is the range of current density?

In electrical wiring, the maximum current density can vary from 4 A⋅mm2 for a wire with no air circulation around it, to 6 A⋅mm2 for a wire in free air.

What should be the range of current density in the stator windings *?

What should be the range of current density in the stator windings? Explanation: The minimum value for the current density in stator winding is 3 A per mm2. The maximum value of the current density in the stator windings should not exceed 5 A per mm2.