What are the differences between three-phase and single-phase transformers?

What are the differences between three-phase and single-phase transformers?

Today, we will mainly compare three-phase and single-phase transformers. Firstly, single-phase transformers were invented first, and three-phase transformers were developed later. This is basic historical knowledge that oil-immersed transformer manufacturers should know. Below, we will compare their differences from three main aspects: feasibility, economy, and reliability. The purpose of introducing these three points is to help users better choose transformers, and these are also areas that consumers pay attention to.

(1) Feasibility. First, it’s common knowledge that the quality of a single-phase transformer is about 40% better than that of a three-phase transformer. Therefore, if a large transformer is to be manufactured as a three-phase transformer, it will definitely be infeasible in terms of transportation and installation. In this case, a single-phase transformer is needed, which allows for better transportation and installation, and has better feasibility!

(2) Economy. First, let’s calculate the transportation cost of the transformer: the transportation weight of a three-phase transformer is about 2.5 times that of a single-phase transformer. If it’s too large, existing bridges may not be able to cross it, so the transportation cost will definitely increase significantly. Moreover, with the current high oil prices, it goes without saying that… Then, from an economic perspective, we usually add a backup transformer because the cost of adding a single-phase transformer is not high, and recovery can be completed in a few days in case of a major accident. However, adding a backup transformer to a three-phase transformer would be extremely costly, and without a backup, the recovery time after an accident could be very long, resulting in greater economic losses. Therefore, single-phase transformers are more economical.

(3) Reliability.

1) Single-phase transformers have a larger internal space, which is beneficial for controlling the electric field strength of the leads in on-load tap-changing transformers with complex tap lines. Operational experience has shown that the operational reliability of single-phase on-load tap-changing transformers is significantly higher than that of three-phase on-load tap-changing transformers.

2) Using a single-phase transformer with a backup phase requires less investment and is more acceptable. With a backup transformer, maintenance and troubleshooting can be carried out in rotation to ensure the normal operation of the transformer. Therefore, for new transformers lacking operational experience, using a single-phase transformer is beneficial for improving the operational reliability of the transformer.