Calculate transformer Room size | Electrical Design
Let’s start:
1- The width of the transformer room is equal to or greater than the width of the transformer used for the building.
For more explanation, see the below image:
In this image you can see there are three conditions: 1, 2, and 3. let’s explain them one by one.
Condition -1
See the first condition as shown in the image: electrical equipment is installed on one wall; it should be transformers or electrical panels, and the opposite side of the electrical equipment has no live or grounded part; the minimum distance is equal to 3ft or 900 mm, as shown in the image.
Example:
First condition is, distance between transformer and Door.
Condition -2
As shown in the image opposite, the electrical panels have grounded parts, like walls. This means the distance between the panels or transformers is equal to or greater than 3 ft. 6 in. or 1 m.
Example:
The second condition is the distance between the transformer and the wall.
Condition: 3
As shown in the above image, the electrical panel opposite is another panel or live part. This means the distance between the transformer and other live parts, like panels or transformers, is equal to or greater than 4 ft or 1.2 m.
Example:
The third condition is the distance between the transformer and another transformer.
Now I will show you how to calculate the transformer room size from the given transformer size chart:
Practical example:
Given data:
- Rating: 1 MVA
- Voltage: 21 kV
- Length: 1970mm, 1.97m
- Width: 980mm, 0.98 m
Calculate transformer room size?
Solution:
As shown in the above NEC table, our transformer rating is 21 kV. We will select 9 to 25 kV.
Condition-1
The distance between the transformer and door is 5ft, 1.524 m.
Condition-2
The distance between the transformer and wall is 6ft, 1.828
Condition-3
The distance between the transformer and another transformer note (if applicable when there are two transformers in one room).
