Grounding Transformer

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产品摘要

The effect of grounding transformer is to lead out the neutral point to connect to the arc suppression coil or resistance when the system adopts △ connection or Y connection and the neutral point cannot be led out. Such transformer adopts Z connection (or called zigzag connection), and it is a manmade neutral point used to connect the grounding resistance. When a ground fault occurs to the system, the transformer will provide high impedance for positive and negative sequence current, and provide low impedance for zero sequence current, so as to ensure reliable operation of ground protection.

产品介绍

1. Brief Description
    The effect of grounding transformer is to lead out the neutral point to connect to the arc suppression coil or resistance when the system adopts △ connection or Y connection and the neutral point cannot be led out. Such transformer adopts Z connection (or called zigzag connection), and it is a manmade neutral point used to connect the grounding resistance. When a ground fault occurs to the system, the transformer will provide high impedance for positive and negative sequence current, and provide low impedance for zero sequence current, so as to ensure reliable operation of ground protection. 
    The grounding transformer is classified into oil type and dry type according to the filing medium, and classified into three-phase grounding transformer and single-phase grounding transformer according to the phase number. 
    The effect of grounding transformer is to lead out the neutral point to connect to the arc suppression coil or resistance when the system adopts △ connection or Y connection and the neutral point cannot be led out. Such transformer adopts Z connection (or called zigzag connection), and its difference from the ordinary transformer lies in, the coil of each phase is divided into two groups, which are reversely wound on the magnetic pillar of such phase respectively, with the advantage that the zero sequence flux may flow along the magnetic pillar, while the zero sequence flux of ordinary transformer flows along the magnetic leakage path. Therefore, the zero sequence impedance of Z-type grounding transformer is tiny (about 10Ω), but that of ordinary transformer is much higher. According to the regulations, if the ordinary transformer carries arc suppression coil, its capacity may not exceed 20% of the transformer capacity. However, Z-type transformer may carry 90% ~100% capacity of arc suppression coil. In addition to the arc suppression coil, the grounding transformer may also carry secondary load to replace the used transformer, so as to save the investment. 

Single-phase grounding transformer 
    The single-phase grounding transformer is mainly applied to the power generators with neutral point and the neutral-point grounding resistor cabinet of Satons transformer, so as to lower the cost and volume of resistor cabinet. 

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