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 1 of 3.

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

K.Ashok kumar said:   1 decade ago
When i solved the problem i am getting 5.5v
given that v1=110,v2=20
we know,turns ratio means n2/n1
so n2/n1=v2/v1
n2/n1=(110/20)
n2/n1=5.5

Debraj said:   1 decade ago
I am confused.

It seems both are correct.

Please tell me the right ans and the right process.

Sushama said:   1 decade ago
My ans is 0.18.

Here,

Given data v1=110 v2=20
We know ratio=n2/n1
So,n2/n1=v2/v1
n2/n1=20/110 = 0.1818182

J.khan said:   1 decade ago
Its so simple

V2/V1= 20/110
0.1818182 ans
Where
v2 Secondry voltage
v1 peri voltage

Amit said:   1 decade ago
N2/N1=V2/V1.

N2/N1= 20/110.

0.18 Answer C.

Tanusri said:   1 decade ago
Can anyone tell me definition of turns ratio? is it N2/N1 or N1/N2 ?

Darshan said:   1 decade ago
N2/N1 is correct N2=secondary turns, N1= primary turns.

Che Lee said:   1 decade ago
The basic formula is
Vs/Vp = Ns/Np where: Vs secondary voltage 20 V
Vp primary voltage 110 V
Ns Secondary turns
Np primary turns

Using the formula gives
20/110 = Ns/Np
0.18 =Ns/Np Remember that turn ratio is Np/Ns
this will give:
Ans: Np/Ns = 5.5 A

* Note: Ns/Np may sometimes use in case of a step up transformer. In this problem it is a step down so Ns/Np is not consider.

Amarjyoti Sarmah said:   1 decade ago
Can anyone correctly give the definition of Turns ratio & Transformation ratio? Is both are the same or inverse to each other? I am very much confused for this two ratios? the above solutions are very much confused. So please help me?


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