# Electrical Engineers And Master Electricians EEAME Portal

...references, ebooks, standards and tutorials

## Time-Current Curves with Excel II

In this part of the tutorial, we shall be able to produce a Normal Inverse time-current curve. Given the values below, we will be plotting the values on an XY Scatter graph with data points connected without markers.

Normal Inverse Curve 400A Setting
I (A) t (s)
600 2.75
800 1.60
1200 1.01
1600 0.80
1600 0.80
1600 0.14
4800 0.14
4800 0.10

Try plotting the values and I presume that you will be getting a graph similar to Figure 1.

Figure 1

To plot a graph similar to Figure 2, the technique is to chunk the data into separate data series.

Data Series 1
I (A) t (s)
600 2.75
800 1.60
1200 1.01
1600 0.80
Data Series 2
I (A) t (s)
1600 0.80
1600 0.14
Data Series 3
I (A) t (s)
1600 0.14
4800 0.14
Data Series 4
I (A) t (s)
4800 0.14
4800 0.10

Figure 2

As I have said in the first part of this tutorial, I presume that you know how to use MS Excel. In the next part, we shall be learning about how to calculate curves for normal inverse, very inverse, extreme inverse and long time inverse.

### Design Stages

Successful projects were not developed overnight. They have undergone through several stages. Missing any one stage may have caused disastrous effect on the projects causing failure.

Conceptual Design
To develop your project ideas into a more tangible perspective.
Front End Engineering and Design (FEED)
To explore possibilities to enable better control on the outcome of ideas, getting the final result without delay but more importantly without overshooting your budget.
All ideas need to be developed at this stage of the project.
Detail Design
The final stage of the design aspect of your project. Only minor, unforeseen and uncontrollable by the project team need to be implemented at this stage.
Injecting radical changes at this stage could mean redevelopment of the project concepts leading to project delays and budget overshoot.

We could offer the Electrical Engineering aspect of your project ideas. If you want to seek our help, contact us at [email protected].