How many transformers are used to create an open delta connection?
Group of answer choices 4 1 2 3
The correct answer and explanation is:
Correct Answer: 2
Explanation:
An open delta connection (also called a V-connection) is a special configuration of transformers used in a three-phase power system. It functions using only two transformers instead of the usual three required for a complete delta connection.
How It Works:
In a standard delta transformer connection, three transformers are used. Each transformer connects between two phases (A-B, B-C, and C-A). This forms a closed triangle or delta shape.
However, in an open delta, only two transformers are used, and the third side of the triangle is left open. Despite this, the system can still supply three-phase power. It is commonly used when:
- One transformer in a delta system fails, and the remaining two are temporarily used to keep the system running.
- The load is light enough that a full delta connection is not necessary.
- A cost-saving or emergency setup is needed.
Key Points:
- Number of transformers used: Only 2
- Power output: An open delta provides 57.7% (or √3/3) of the power output compared to a full delta connection, assuming equal transformer ratings.
- Applications: Ideal for light loads, temporary service, or where cost efficiency is needed.
Example:
Suppose a factory has a 3-phase motor system and one of the delta-connected transformers fails. Instead of shutting down, they can reconfigure the system into an open delta using the two remaining transformers. Although it won’t deliver full power, it allows continued operation at reduced capacity until repairs are made.
Conclusion:
An open delta transformer connection uses 2 transformers to provide three-phase power under limited capacity.