Help choose the transformer capacity
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Now, it is necessary to supply power to a chemical plant. Due to insufficient information, it can only be determined that the rated capacity of all low-voltage equipment is around 3700 kW, including the backup equipment. This figure represents the total load, not the calculated load. What size transformer should I choose? Would two units of 2500 KVA each be sufficient? What are the capacities of transformers these days? Also, when selecting capacity based on the computational load, is it necessary to take into account the capacity of the uninterruptible power supply? Are there any other loads as well?
1# Yuebing, in accordance with GB/T6451 – “Technical Parameters and Requirements for Three-Phase Oil-Immersed Power Transformers”, has voltage levels ranging from 10kv to 220kv. The capacity is as follows (in kVA): Lower grades: 30, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800; Medium grades: 1000, 1250, 1600, 2000, 2500, 3150, 4000, 5000, 6300, 8000; Higher grades: 10000, 12500, 16000, 20000, 25000, 31500, 40000, 50000, 63000, 90000; Ultra-high grades: 120000, 150000, 180000, 240000, 300000, 360000. For 24/7 continuous operation, two transformers of 3150 KVA each should be selected
When selecting the capacity of a transformer, it is necessary to take into account the type of load – whether it is a secondary load, a primary load, or a tertiary load. The power supply methods for these different types of loads vary. According to the information provided, which seems incomplete, if all the loads are primary loads, then two 2500 kVA transformers will not be sufficient. On the other hand, if it are tertiary loads and a significant portion of them constitutes standby loads, then two 2000 kVA transformers will suffice. The capacity of the transformers is 1000 kVA and 1250 kVA; it seems that each subsequent level is 1.25 times the previous one. Determining the capacity of the transformer is quite important; it is recommended to identify the types of loads, determine the power supply method, consider the amount of backup load, as well as the calculated load level.
The utilization rate in chemical enterprises is at most 50%; that is, one unit is kept as a backup so that the other cannot operate at full capacity. Based on the load requirements, a multiplier is applied, and two 1600KVA transformers are sufficient.