Distribution transformers are crucial hubs in modern power supply systems, ensuring stable transmission and efficient distribution of electrical energy. When it comes to electrical design, many professionals wonder why the Dyn11 connection distribution transformer is preferred in most cases. This article will elaborate on the core advantages of Dyn11 connection and its wide application scenarios, with a focus on the oil filled distribution transformer and 11kv to 400v transformer, which are widely used in industrial and civil fields.
I. Main Connection Groups of Distribution Transformers
For 6~10kV power transformers with a 400V low-voltage side in a three-phase four-wire system, there are two main connection groups: Dyn11 (Δ/Y0-11) and Yyn0 (Y/Y0-12). In the past, Yyn0 connection transformers were almost universally used in China, but now Dyn11 connection has become the mainstream choice in most countries around the world, especially for the 11kv to 400v transformer and oil filled distribution transformer. The reason lies in the obvious advantages of Dyn11 connection over Yyn0 connection.
II. Core Advantages of Dyn11 Connection Transformers
First, the 3n-th (n is a positive integer) harmonic excitation current of the Dyn11 connection transformer forms a circulating current in its D-connected primary winding, which will not be injected into the public high-voltage power grid. This is more conducive to suppressing high-order harmonic currents than the Yyn0 connection transformer whose primary winding is Y-connected. For the oil filled distribution transformer with Dyn11 connection, this advantage can effectively protect the internal components of the transformer and improve the quality of power supply.
Second, the zero-sequence impedance of the Dyn11 connection transformer is much smaller than that of the Yyn0 connection transformer, which is more conducive to cutting off the short-circuit fault of low-voltage single-phase grounding. This is particularly important for the 11kv to 400v transformer used in civil and industrial fields, as it can quickly respond to faults and ensure the safety and stability of the power supply system.
Third, the Dyn11 connection transformer has a much higher ability to bear single-phase unbalanced loads than the Yyn0 connection transformer. The neutral line current of the Yyn0 connection transformer is generally not allowed to exceed 25% of the rated current of its low-voltage winding, while the neutral line current of the Dyn11 connection transformer can be allowed to exceed 75% of the rated current of the low-voltage winding. This makes the Dyn11 connection oil filled distribution transformer more suitable for scenarios with complex loads, such as residential buildings, theaters and financial buildings.
III. Standards and Specifications for Dyn11 Connection Transformers
Relevant international and domestic standards also clearly recommend the use of Dyn11 connection distribution transformers. GB50052-2009 "Code for Design of Power Supply and Distribution Systems" stipulates that in the low-voltage power grid with TN and TT system grounding forms, three-phase transformers with Dyn11 connection group should be preferred as distribution transformers. GB51348-2019 "Standard for Electrical Design of Civil Buildings" also emphasizes that distribution transformers should prioritize the Dyn11 connection group, which is particularly applicable to the 11kv to 400v transformer and oil filled distribution transformer in civil buildings.
IV. Application of Dyn11 Connection Transformers in Specific Fields
In specific fields, the advantages of Dyn11 connection are more prominent. For theaters with high harmonic usage, JGJ 57-2016 "Code for Design of Theater Buildings" clearly points out that theater distribution transformers should adopt Dyn11 connection, which can effectively suppress the impact of harmonics and three-phase load imbalance on the power supply system. In the field of financial buildings, JGJ 284-2012 "Code for Electrical Design of Financial Buildings" recommends that financial facilities should choose distribution transformers with low no-load loss and Dyn11 winding connection, which can ensure the stable operation of financial equipment.
V. Dyn11 Connection Transformers from JINSHANMEN TECHNOLOGY
As a professional manufacturer of power transmission and distribution equipment, JINSHANMEN TECHNOLOGY CO., LTD has rich experience in producing Dyn11 connection transformers. The company mainly produces oil immersed power transformers, dry-type power transformers, oil immersed three-dimensional coiled power transformers, dry-type three-dimensional coiled power transformers, mining explosion-proof dry-type transformers, mining explosion-proof mobile substations, amorphous alloy power transformers, on load capacity regulating power transformers, locomotive dry-type transformers, as well as prefabricated substations, modular substations, wind energy box type substations, high and low voltage switchgear and other transmission and distribution equipment. Our oil filled distribution transformer and 11kv to 400v transformer with Dyn11 connection are widely praised by customers for their stable performance, high efficiency and energy saving.
VI. Summary
In summary, the Dyn11 connection distribution transformer has obvious advantages in suppressing high-order harmonics, handling unbalanced loads and cutting off faults. It is the preferred choice in civil buildings, residential buildings, theaters, financial buildings and other fields. Choosing the Dyn11 connection oil filled distribution transformer and 11kv to 400v transformer can not only improve the efficiency and stability of the power supply system, but also effectively reduce energy consumption and ensure electrical safety.