Selection between dry-type and oil-immersed transformers
Thread Content
Last edited by zxg.wylton on 2022-5-28 06:36 in this post. Question: There are double-circuit 35kv overhead lines outside the plant area. The calculated load of this chemical plant is 9100kw, with electrical equipment mainly operating at 10kv and 0.4kv levels, at the secondary level. In the future, a 10kv waste heat power generation unit will also need to be installed. For the reduction from 35kv to 10kv, it is planned to install two transformers with a capacity of 16,000 kva each. 1. The comprehensive building in the plant area (substation + control room + offices) is equipped with 35kV and 10kV high and low voltage substations, all of whose transformers are dry-type transformers. Saves space. 2. For 35KV, an oil-transformer is used (options for indoor or outdoor installation can be considered), and it is installed on the ground near the overhead lines. After stepping up to 10kv, enter the complex building. The space on site is quite limited; there is a lot of dust, rain, and thunderstorms, with humidity remaining above 85% throughout the year, and temperatures ranging from 25 to 32 degrees. Based on the above basic situation, by how many tens of thousands will the investment estimates for the two options differ? How to make a choice? Thank you!
Ahah, I’m here to complain about this poster! Based on what the poster has described, dry-type transformers are used in distribution systems of 10 KV and below; they are the preferred choice. Not only do they help reduce construction costs, but they also save on the costs associated with the distribution buses between the transformer room and the low-voltage MCCs. Installation and subsequent maintenance are also simpler, and the maintenance costs are lower compared to oil-immersed transformers. The downside is that when dry-type transformers are installed adjacent to the low-voltage MCCs, the heat generated by the transformers may increase the costs related to air conditioning operation Regarding the main transformer on the high-voltage side, which is connected directly to the external power grid and requires frequent operation or on-load voltage regulation, an on-load voltage-regulating oil-immersed transformer is a more reliable choice ； At the same time, land savings can be considered by using an indoor installation method; this not only protects it from external factors such as weather and pollution, but also enhances operational reliability! The above power distribution system approach is now very common and widely used! Regarding the cost issue, it is possible to entrust a professional to conduct a price comparison.
There is no dispute that 10KV transformers definitely use dry-type transformers. 35kv dry-type transformers are now being used more frequently, with a maximum capacity of 50,000. This power grid operates as an isolated system abroad; therefore, there is no need for on-load voltage regulation, nor is it necessary to consider the costs associated with air conditioning.
You can find a few suppliers and get several proposals to consider
The supplier doesn’t matter; the transformer products are definitely of good quality. But they have not done system design, so they are unable to provide targeted and comprehensive advice. A design institute needs to be found. It is not prohibited by regulations.
Dry-type transformers are much more expensive than oil-immersed transformers, but they require simple maintenance and can be placed in the same room as the distribution panel. Oil-immersed transformers require a separate transformer room, and their maintenance is somewhat more complex than that of dry-type transformers. When comparing the two options, the cost of dry curing is higher. The recommendation is to use oil-immersed transformers for 35KV and dry-type transformers for 10KV; this configuration is preferable.
It still depends on your civil engineering and land costs; if you only consider the equipment, then dry-type transformers will definitely be more expensive.
I just want to know the actual case data from everyone, including comparisons made by taking into account various factors such as the choice between aluminum and copper for dry-type transformers
Some people are very averse to having 35kv systems near administrative offices, as if they were time-triggered bombs