# Calculate Transformer Over current Protection (As per NEC 450.3)

## Calculate Transformer Over current Protection (NEC 450.3)

• Calculate Size of Circuit Breaker on Primary side of Transformer as per NEC 450.3
• Calculate Size of Fuse on Primary side of Transformer as per NEC 450.3
• Calculate Size of Circuit Breaker on Secondary side of Transformer as per NEC 450.3
• Calculate Size of Fuse on Secondary side of Transformer as per NEC 450.3
• Calculate Size of Transformer
• Calculate Transformer Full Load Losses

Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical) from Gujarat University. He has more than 14 years experience in Power Transmission-Power Distribution-Electrical energy theft detection-Electrical Maintenance-Electrical Projects(Planning-Designing-coordination-Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He is Freelancer Programmer of Advance Excel and design useful Excel Sheets of Electrical Engineering as per IS,NEC,IEC,IEEE codes. He is technical Author for "Electrical Mirror" and "Electrical India" Magazines. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

### 6 Responses to Calculate Transformer Over current Protection (As per NEC 450.3)

1. ananthanarayanan ramesh says:

Hello Jignesh,

I feel that many engineers will be glad if you could also indicate the formula for calculation also

• This program is mad on my previous post :https://electricalnotes.wordpress.com/2012/09/18/abstract-of-over-current-protection-of-transformer-nec-450-3/. Here I gave full description and gave example for that.

You are right I agree that by Formula we can easily understand the Program
I always do not lock formula of sheet. we can easily see the equation,which is indicate in excel sheet task bar.
All Program is basically combination of Formula and Logic.Some Time it is not Possible to evaluate complete formula in Program because from some reference value We have to used Table Which is not Possible to show in sheet. Logic condition also not possible to indicate in Program.
Normally the Basic equation of the Program is indicated in the end of the Program
For complete study of the Program It is easiest way to study the task bar of the sheet here we can get both Formula and Logic.

2. Khin Shwe says:

Thank you for your Electrical notes.
It is very useful for us.
I say again, thank you very much.

3. ketan says:

dear jiganesh
i like very much your artical

please understand me Transformer IDMT Over Current & Earth Fault Relay Setting.

4. MD Irfan Alam says:

Thank you for your Electrical notes.
It is very useful for us.

5. Anantha Murthy. C says:

Hi Jignesh,
I am one of the regular reader of your electrical notes & Articles. These notes are very informative and very useful. I intend to buy the un-lock sheets of electrical programs. Please tell me the method of buying the same. Once i tried through on line, but it was unsuccessful. It was indicated that I am indian. Please also clarify that does the unlocked version contains metholodogy of electrical calculation and formulas. Please reply to my e-mail id anantha.krcl@gmail.com