Transformer selection recommendations

First of all, you can choose according to the transformer implementation standard. At present, the standard implemented by my country's transformers is GB 20052-2020 "Energy Efficiency Limit Values and Energy Efficiency Grades for Power Transformers". This national mandatory implementation standard will be implemented on June 1, 2021, replacing the old version of GB 20052-2013 and GB 24790-2009. In the new version, the no-load loss and load loss indicators have been greatly improved, and the first-level energy efficiency is better than the EU, US, and Japanese standards, which has promoted the popularization of high-efficiency and energy-saving transformers. According to the "Transformer Energy Efficiency Improvement Plan (2021-2023)", starting from 2023, new transformers added to the power grid must comply with the level 1 or level 2 energy efficiency standards of GB 20052-2020, and the proportion of high-efficiency and energy-saving transformers must reach more than 75%. Transformers certified by the China Quality Certification Center (CQC) can be marked with the "Save" logo, which can be used as a reference when purchasing.

The name of the transformer can also help in selecting a transformer. According to JB/T 3837-2016 "Method for Compiling Models of Transformer Products", the model includes information on structure, material, capacity, voltage and energy efficiency level. For example: SM·RL-2000/10-NX1, S: three-phase; M: sealed; RL: three-dimensional wound core; 2000/10: capacity 2000kVA, high-voltage side 10kV; NX1: first-level energy efficiency (NX2 is second-level energy efficiency).

In addition, parameters are particularly important when purchasing transformers. If you choose according to the use environment, oil-Immersed Transformers (such as S11-M) or dry-type transformers (such as SCB13) are recommended in normal environments. In high-rise buildings and where there are fire protection requirements, it is recommended to choose non-flammabledry-type transformers (epoxy resin cast SCB series) or high-ignition-point oil transformers. In dusty and corrosive environments, you can choose closed or gas-filled transformers (such as SF6 insulation). If you choose according to capacity and load, you can refer to GB/T 17468-2019 "Guidelines for the Selection of Power Transformers". Combined with the calculated load to determine the capacity, dry-type transformers must comply with GB/T 1094.12-2013 load guidelines. Oil-immersed and dry-type transformers can be selected according to the insulation level: the oil-immersed level is A (heat resistance 105℃). The dry level is F (155℃) or H (180℃). There are two loss indicators, one is no-load loss and the other is load loss. No-load loss is the active power loss when there is no load (low-loss models are preferred), and load loss is the active power loss under rated current (refer to GB 20052-2020 limit).

When selecting a transformer, you need to consider all aspects to ensure that the product complies with national standards (such as oil-immersed transformers comply with GB/T 6451, and dry-type transformers comply with GB/T 10228); you should give priority to Class 1 or Class 2 energy-efficient transformers (marked with NX1/NX2) to reduce long-term operating costs; Evaluate the manufacturer's technical strength, product life and after-sales service; comprehensively consider initial investment, operating losses (no-load/loaded) and maintenance costs.