Key Selection Points for Oil-Immersed Transformers

Load Character

1) When there is a large amount of first or second-class load, it is advisable to install two transformers or more. In the event that any one transformer is disconnected, the remaining transformers' capacity will be sufficient to meet the power demands of the first and second-class loads. It is preferable to concentrate the first and second-class loads as much as possible and avoid excessive dispersion.

2) Transformers should be installed during peak seasonal loads, such as for air conditioning chillers in large residential buildings and electric heating loads for heating.

3) Transformers are recommended when there is a high load concentration, such as with large heating equipment, large X-ray machines, and arc furnaces.

4) In cases where the lighting load is heavy or when the shared transformer between power and lighting significantly affects lighting quality and bulb lifespan, a lighting transformer can be installed. Generally, power and lighting use a shared transformer.

Utilizing Environment

Under normal medium conditions, oil-immersed transformers or dry-type transformers can be selected, such as those in industrial and mining enterprises, agriculture, or attached transformer substations, residential community transformer substations, etc. Available transformer options include S8, S9, S10, SC(B)9, SC(B)10, etc.

Temperature Environment

At 220°C, maintains long-term stability.

At 350°C, it can withstand short-term operation.

Maintains stable performance over a wide range of temperatures and humidity.

At 250°C, it will not melt, flow, or support combustion.

At 750°C, no toxic or corrosive gases are released.

Electricity Load

1) The capacity of distribution transformers should be determined by considering the facility capacities of various electrical equipment, calculating the load (usually excluding fire load), and the apparent capacity after compensation serves as the basis for selecting transformer capacity and quantity. Generally, the load factor of transformers is around 85%. This method is relatively simple and can be used for estimating capacity.

In the GB/T17468-1998 "Guidelines for Selection of Power Transformers," the capacity selection of distribution transformers should be determined based on the GB/T15164-94 "Guidelines for Load of Oil-Immersed Power Transformers" or GB/T17211-1998 "Guidelines for Load of Dry-Type Power Transformers" and the calculated load. These two guidelines provide computer programs and normal periodic load diagrams to determine the capacity of distribution transformers.