变压器的接法（Connection method of transformer）.docVIP

变压器的接法（Connection method of transformer） Connection of transformer At present, there are two common connection methods for transformers: Y and D, and Z transformers are used in distribution transformers. The advantages of 1. Y connection: the economy of the high voltage winding; can allow for the use of neutral point; grounding directly or through impedance grounding; allow to reduce the insulation level of the neutral point (graded insulation); tap can be set in each phase of neutral point switch can also point in; allowed to receive single-phase load, the neutral point can load flow. 2., D connection advantages: for large current low-voltage winding is the most economical; and Y winding used in conjunction can reduce the zero sequence impedance value. 3. advantages of Z connection method: allow the neutral current carrying load and zero sequence impedance low; can be used as a grounding transformer connection form artificial neutral point; can reduce the system voltage imbalance (system three-phase unbalanced load); can be used as a method to use thunder region distribution transformer. The above is the advantage of a single connection method, the general transformer has at least two windings, so the transformer has several combinations of methods. A., YN, YN, and O YN (YN self coupling) Zero sequence current will be converted in the windings, i.e. high voltage and low voltage winding has zero current, and to achieve the transformer ampere turns balance of zero sequence impedance is low, the system of transformer, there must be a D connected with this balance winding connection together with. B., YN, y, and Y YN There is zero sequence current winding neutral point lead, but in another winding without neutral point in the current, the zero sequence current can not be the core for ampere turn balance, a magnetizing zero current, zero sequence impedance by excitation control, according to the design of the magnetic circuit, the zero sequence impedance can be larger (