Three Phase Z-type winding Oil-Immersed Earthing Transformer source manufacturer 10kV-35kV

The differences between the two stem from the essential difference in functional positioning, specifically reflected in three aspects: ① Different core functions: ordinary power transformers focus on voltage transformation and energy transmission, while earthing/grounding transformers focus on constructing neutral points and providing fault current paths; ② Different capacity calibration: ordinary power transformers are marked with continuous operating capacity (long-term load capacity), while earthing/grounding transformers are marked with short-time rated capacity (capacity that can be carried within a specified time based on fault current and withstand time, such as 30 seconds); ③ Different winding designs: earthing/grounding transformers mostly adopt special winding structures such as zigzag (ZN), while ordinary power transformers mainly use conventional windings such as star and delta, and earthing/grounding transformers usually have no traditional voltage transformation ratio.

An earthing/grounding transformer is a special type of transformer that artificially creates a neutral point for ungrounded or low-current grounded power systems. It constructs a grounding circuit through a specific winding design, with two core functions: first, to provide a low-impedance path for zero-sequence current in the system, ensuring that the fault current reaches the operating threshold of the relay protection device when a single-phase ground fault occurs, enabling rapid fault location and isolation; second, to maintain system voltage balance, suppress excessive voltage rise of non-fault phases during faults, and protect the insulation safety of power grid equipment. Unlike ordinary power transformers, its core function is to "construct a grounding circuit" rather than "voltage transformation", and it is usually designed according to short-time load capacity instead of continuous operating capacity.