Thanks for your help.Transformer Ratings: Questions & Answers

In summary, a transformer's kVA rating refers to both the input and output side and power per phase in a three phase transformer is one-third of the overall power rating.
  • #1
Lunat1c
66
0
Hi,

I have a couple questions regarding transformers:

1. When you're told that a particular transformer is rated at 2000kVA, is that referring to the output or to the input rating of the TX? Or is it correct to say that the apparent power on both windings will be equal to that?

I view the 2000kVA as the maximum loading of the transformer (even though it can be overloaded a bit with the correct setup) however with this in mind I'm having doubts whether I can use S=VI on any of the two windings.

2. If you have a 2000kVA three-phase 30000/6000V transformer connected as delta-star, then is the apparent power per phase equal to 2000kVA or is that the total?
 
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  • #2
Seeing how this post is a couple of months old and no one has replied, I'll assume that the OP has either given up, or found the answer to his questions.

In the interest of answering these questions for those interested, I have decided to post my answers even though this is a homework forum.


1. The kVA rating of a transformer refers to both the primary (input) and secondary (output) side of the transformer. Remember, power in equals power out. Of course, there is a bit of loss due to heat, but for the sake of calculations, a "perfect" transformer is considered (that is, one that loses no power to heat).

2. The power per phase of a three phase transformer is one-third the overall power rating of the transformer (whether delta- or wye-connected). So, there would be approximately 667 kVA per phase.



For more information, see: http://ecmweb.com/mag/electric_understanding_basics_wye/
 

1. What is the purpose of transformer ratings?

The purpose of transformer ratings is to ensure that the transformer is able to safely and effectively convert electrical energy from one voltage level to another without exceeding its capacity.

2. What are the different types of transformer ratings?

The different types of transformer ratings include voltage rating, current rating, power rating, and frequency rating. These ratings indicate the maximum voltage, current, power, and frequency that the transformer can handle.

3. How are transformer ratings determined?

Transformer ratings are determined through testing and calculations based on the transformer's design, materials, and intended use. The manufacturer will also take into account safety standards and regulations when determining the ratings.

4. Can transformer ratings be changed?

No, transformer ratings cannot be changed without significant modifications to the transformer itself. The ratings are determined during the design and manufacturing process and should not be altered without proper testing and approval.

5. What happens if a transformer is operated above its ratings?

If a transformer is operated above its ratings, it can overheat and potentially fail. This can lead to electrical fires, damage to equipment, and power outages. It is important to always operate transformers within their designated ratings to ensure safety and efficiency.

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