Electrical Engineering - Transformers - Discussion

Discussion Forum : Transformers - General Questions (Q.No. 7)
7.
To step 110 V ac down to 20 V ac, the turns ratio must be
5.5
18
0.18
0.018
Answer: Option
Explanation:

Vp/Vs = Np/Ns

Vs = (Ns/Np)Vp

We required turns ratio i.e., (Ns/Np)

= Vs/Vp

= 20/110

= 0.181818182

[Note: p - primary; s - secondary]

For step down transfer, the turns ratio will be less than 1.

For simulation: Step-Down Transformer Circuit Simulator.

Discussion:
29 comments Page 2 of 3.

Amani naidu said:   9 years ago
n2/n1 is the transformation ratio.
n1/n2 is the turns ratio.
n1/n2 = v2/v1.

So, the answer is 0.1818.

Pintu kumar said:   9 years ago
I am confused please give me the correct answer.

Masroor said:   10 years ago
As the t/f is step down t/f, so the secondary is 20 V & the primary is 110 V.

And according to formula:

Ns/Np=Vs/Vp.

Ns/Np=20/110.

Hence; Ns/Np=0.18.

Lavkesh said:   10 years ago
n2/n1 = v2/v1 and i1/i2.

But here we required only n2/n1 = 20/110 = 0.18.

Vinit Ghone said:   1 decade ago
What is the main turns ratio? Am way to confused. Please help me. What's is the relation v2/v1 = i1/i2 = n2/n1 or what?

Rajashekhar said:   1 decade ago
When I solved this problem am getting as 5.5 value. Kindly confirm me.

Sainath goud said:   1 decade ago
Turns ratio is N1/N2.

We know that N1/N2 = V2/V1.

N1/N2 = 20/110 = 2/11 = 0.181.

Bharath reddy said:   1 decade ago
I'm confused 0.18, 5.5 I think correct answer 0.18.

Akash.bhure said:   1 decade ago
Solution:

Primary voltage(V1) = 110V.
Secondary voltage(V2) = 20V.
Turns ratio(K) = N2/N1 = V2/V1.
(K) = 20/110 = 0.18.

Vivek prasad said:   1 decade ago
According to IEEE, Turns ratio = high voltage turns / low voltage turns
So turn ratio = 110 / 20 = 5.5.


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