# Merits and Demerits of Current transformer secondary winding turns

#### Touseef

Sep 29, 2015
5
Hi..
this is my first post in this forum, please give me details on the current transformer
what is the impact of having secondary turns lesser than 100 turns
& vice verse.

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
12,733
Less turns = higher secondary current
More turns = less secondary current

Where do you take the magic number 100 from? You can have current transformers with widely varying turns ratios, depending on your application.

#### Touseef

Sep 29, 2015
5
Less turns = higher secondary current
More turns = less secondary current

Where do you take the magic number 100 from? You can have current transformers with widely varying turns ratios, depending on your application.
have designed my own CT(ferrite core coil) with just 30 turns, bcuz of lesser primary current about 0.1A, does it have any drawbacks in long run. thanks for your reply

#### duke37

Jan 9, 2011
5,364
The number of turns affects the impedance of the transformer secondary. This should be considerably higher than the load resistance. I expect that you are using a high frequency if you have a ferrite core.

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
12,733
does it have any drawbacks in long run
What are you thinking of?
If the transformer and the circuit surrounding it are designed properly (i.e. with respect to impedances, wire gauges, current flowing etc.) and works correctly, which long term effects would you expect?

#### Touseef

Sep 29, 2015
5
someone give some basics of burden resistor, design guide, applications for it. please ignore my lack of knowledge on it by degrading questions. i appreciate your response.

#### Touseef

Sep 29, 2015
5
The number of turns affects the impedance of the transformer secondary. This should be considerably higher than the load resistance. I expect that you are using a high frequency if you have a ferrite core.
how to calculate impendance by no of turns, can u give me an example of it. thanks

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