Parallel operation of transformers is a common practice in power systems where multiple transformers are connected together to share the load. However, for transformers to operate in parallel, certain conditions must be met to ensure that the transformers operate safely and efficiently. The first condition for parallel operation is that the transformers must have the same voltage ratio and phase shift. This means that the transformers must be identical or have the same impedance ratio. Otherwise, if the transformers have different voltage ratios, the transformers may not share the load equally, and some transformers may be overloaded.

The second condition is that the transformers must have the same phase sequence. This means that the polarity of the primary and secondary windings must be the same for all transformers. If the phase sequence is not the same, the transformers may not share the load equally, and the circulating current between the transformers may cause overheating and damage.

The third condition is that the transformers must have the same impedance or impedance ratio. This is to ensure that the transformers share the load equally and that there is no voltage unbalance between the transformers.

In addition to these conditions, the transformers should have the same cooling characteristics, insulation class, and impedance voltage drop. Proper protection devices and control circuits should also be installed to ensure the safety and reliability of the parallel operation. In conclusion, parallel operation of transformers can increase the power supply reliability and flexibility. However, to ensure safe and efficient operation, the transformers must meet certain conditions and requirements.

When two or more transformers are connected in parallel, it is important to ensure that they share the load equally. This requires that the transformers be of identical rating, have the same percentage impedance, and be connected with proper phase rotation. In addition, the voltage ratios of the transformers must be the same, or else a circulating current may flow between the transformers, causing overheating and reducing efficiency. Parallel operation can be achieved by using external load tap changers, which can adjust the output voltage of each transformer to achieve equal sharing of the load. Alternatively, transformers can be designed with on-load tap changers, which allow the voltage ratio to be adjusted without interrupting the load. In either case, proper maintenance and monitoring is essential to ensure the safe and efficient operation of the parallel transformers.

LuShan, est. 1975,  is a Chinese professional manufacturer specializing in power transformers and reactors for 48 years. Leading products are single-phase transformer, three-phase transformers, DC inductors, AC reactors, filtering reactor, expoxy resin high-voltage transformer and intermediate, high-frequency products. Our transformers and reactors are widely used in 10 application areas: rapid transit, construction machinery, renewable energy, intelligent manufacturing, medical equipment, coal mine explosion prevention , excitation system, vacuum sintering, central air conditioning.

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