Paralleled Transformers: Why Overload & How to Prevent It?

In summary, when paralleling transformers with different kVA ratings, the smaller transformer may become overloaded while the larger one is lightly loaded due to differences in impedances and power/current sharing. To prevent overloading, accurate calculations or load-flow programs must be used to determine the splits in current and power between the parallel branches. Additionally, creating a loop through both transformers may cause issues and should be done with caution.
  • #1
Nahian
4
0
When transformers with the same turns ratio, but different kVA ratings are paralleled , it is possible for the smaller transformer to be overloaded and the larger transformer to be lightly loaded.Why is it so? Can anyone please show mathematical and theoretical explanation?And what can be done to stop the overloading of the transformer?
 
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  • #2
The impedances will be different. Therefore, the sharing of power and current between the parallel branches will not necessarily be in proportion to their KVA ratings.

If you can't do the calculations by hand, any load-flow program modeling those transformers in parallel will calculate the splits in current and power.
 
  • #3
Thanks
 
  • #4
Nahian said:
When transformers with the same turns ratio, but different kVA ratings are paralleled
Then you are creating a loop - through transformer A and back through transformer B. Be very careful!
 

FAQ: Paralleled Transformers: Why Overload & How to Prevent It?

Why do paralleled transformers experience overload?

Paralleled transformers can experience overload due to imbalanced loading, unequal distribution of load, or incorrect sizing of the transformers. This can lead to one transformer taking on more load than it can handle, causing it to overheat and potentially fail.

How does overload affect paralleled transformers?

Overloading can cause damage to the transformers, leading to reduced efficiency, increased energy consumption, and potential failure. It can also result in power outages and disruptions to the electrical system.

How can I prevent overload in paralleled transformers?

To prevent overload in paralleled transformers, it is important to ensure that the transformers are properly sized and matched to the load. Regular maintenance and monitoring of the transformers can also help identify any imbalances or issues that could lead to overload. Implementing load-sharing techniques and using protective devices such as fuses and circuit breakers can also help prevent overload.

What is the effect of unequal distribution of load on paralleled transformers?

Unequal distribution of load can cause one transformer to carry more load than the others, leading to overload and potential damage. It can also result in decreased efficiency and increased energy consumption.

What are some common signs of overload in paralleled transformers?

Some common signs of overload in paralleled transformers include increased temperature, excessive noise, flickering lights, and a burning smell. These signs should not be ignored and should be addressed immediately to prevent further damage.

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