How to choose the capacity of the distribution substation transformer?
1. When we usually choose distribution substation transformer, if the capacity is too large, the phenomenon of big horse-drawn trolley will be formed, which will not only increase equipment investment, but also keep the transformer in a no-load condition for a long time. If the transformer capacity is too small, the transformer will be in an overloaded state for a long time, and it is easy to burn the transformer, whether it is an autotransformer or a three-phase transformer, it is the same. Therefore, the correct selection of transformer capacity is one of the important measures to reduce losses and save energy in the power grid. In practical applications, we can choose the transformer capacity according to the following simple methods.
2. We should adhere to the principle of capacity, dense distribution, distribution substation transformer should be located in the load center as much as possible, and the power supply radius should not exceed 0.5 kilometers. The load rate of the distribution transformer is the highest between 0.5 and 0.6, and the capacity of the transformer at this time is called the economic capacity. However, if the load is relatively stable, the transformer capacity can be selected according to the economic capacity in the case of continuous production.
3. According to the characteristics of scattered rural power grid users, small load density, strong load seasonality and strong intermittent, capacity-adjusting transformers can be used. The capacity-adjusting transformer is a transformer that can adjust the capacity without load according to the size of the load. It is suitable for use in places with obvious seasonal changes in the load. For substations or industrial and mining enterprises with a large power load, the mother and child transformers are generally used for power supply. One (mother) is configured according to the maximum load, and the other (secondary) is selected according to the low load state, which can greatly improve the power distribution. Transformer utilization, reduce no-load loss of distribution transformers. In view of the fact that some distribution substation transformer in rural areas are in low-load operation for a long time except for a small amount of peak electricity load in a year, for users with conditions, the power supply mode of parallel operation of mother-son transformers or transformers can also be used. When the load changes greatly, according to the principle of the lowest power loss, put into transformers of different capacities. For special transformers that only supply power to power loads such as irrigation and drainage, the capacity of the transformer can generally be selected according to 1.2 times the nameplate power of the asynchronous motor. Generally, the starting current of the motor is four to seven times the rated current, and the transformer should be able to withstand this impact. The capacity of the largest one of the directly started motors should generally not exceed 30% of the transformer capacity. It should be pointed out that the special transformer for drainage and irrigation should generally not be connected to other loads, so as to stop the operation in time during the non-drainage and irrigation period and reduce the loss of electric energy.
4. For the selection of the capacity of comprehensive power transformers for power supply and lighting, agricultural and sideline product processing, etc., the simultaneous power of the electrical equipment should be considered. The capacity of the transformer can be selected according to 1.25 times the actual maximum load that may occur. In short, we are choosing a transformer You should pay attention to the capacity.
