Three phase Oil Immersed Grounding /Earthing Transformer Manufacturer 15kV-35kV

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Key attributes

Brand	ROCKWILL
Model NO.	Three phase Oil Immersed Grounding /Earthing Transformer Manufacturer 15kV-35kV
Rated voltage	33kV
Phases	Three-phase
Frequency range	50/60Hz
Series	JDS

Description

Rockwill three-phase oil-immersed Z-type earthing transformers are designed for medium-voltage power systems requiring a reliable artificial neutral point. Featuring a fully sealed oil-immersed structure with optimized zigzag (ZN) winding, these transformers provide stable neutral grounding for ungrounded or low-current grounded systems from 15 kV to 35 kV.

They effectively suppress arc grounding overvoltage, limit ground fault currents, and enhance grid stability. Manufactured in compliance with IEC standards, these units are suitable for distribution substations, renewable energy plants, and industrial power distribution.

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Key Features

Medium-Voltage Neutral Grounding ：Provides an artificial neutral point for ungrounded or delta-connected systems, enabling connection of arc suppression coils or neutral grounding resistors.
Optimized Z-Type Winding ：Zigzag (ZN) winding configuration delivers low zero-sequence impedance, ensuring efficient fault current path and sensitive relay protection.
Oil-Immersed Fully Sealed Construction：Durable sealed tank design with mineral oil insulation ensures long service life, strong overload capacity, and maintenance-free outdoor operation.
Flexible Cooling Options ：Available with ONAN, ONAF, AN, or AF cooling systems to match application load profiles and ambient conditions.

Technical Parameters

Parameter	Value
Highest voltage for equipment (Um)	17.5 / 24 / 36 / 40.5 kV
Rated frequency	50 / 60 Hz
Number of phases	Three
Connection group	ZN (zigzag)
Rated neutral current	Up to 3000 A
Rated short-time duration	10 s / 30 s / 60 s (customizable)
Zero-sequence impedance (Zo)	Per project specification (tolerance ≤ ±10 %)
Cooling method	ONAN / ONAF / AN / AF
Insulation medium	Mineral oil
Auxiliary winding	Optional
Ambient temperature	–40 °C to +40 °C
Installation	Indoor or outdoor
Enclosure options	IP-rated cabinet; optional CT, VT, or isolation switch

Insulation Levels by Voltage Class

System Voltage	Um (kV)	PF (kV)	LI (kV)
15 kV	17.5	38	95
22 kV	24	50	125
30 kV	36	70	170
33 kV	36	70	170
35 kV	40.5	95	200

Applications

Medium-voltage distribution network neutral grounding
Wind farm and photovoltaic power station grid connection
Industrial and mining enterprise power distribution
Utility substations and switching stations
Urban power grid upgrading and renovation

Solutions for Earthing Transformer

Intelligent Maintenance Services and Sustainable Solutions for Z-Type Grounding Transformers

Intelligent Maintenance Services and Sustainable Solutions for Z-Type Grounding TransformersZ-type grounding transformers are critical for stabilizing ungrounded or delta-connected power systems by providing a low-impedance path for zero-sequence currents during faults. Integrating intelligent maintenance and sustainability practices enhances their reliability while minimizing environmental impact. Below is a structured analysis of advanced solutions:I. Intelligent Maintenance Services Real-Time

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Documentation Resource Library Earthing Transformer

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FAQ for Earthing Transformer

Q: What are the characteristics of the "no-load loss" and "load loss" of earthing/grounding transformers, and do they have a significant impact on operating costs?

Its loss characteristics are highly related to operating characteristics: ① No-load loss refers to the iron loss (core hysteresis and eddy current loss) during normal operation. Due to long-term no-load/light load status, it is the main operating loss; ② Load loss refers to the copper loss (winding resistance loss) during faults, which is only generated during short-time faults and accounts for a very low proportion. The impact on operating costs needs to be divided by scenarios: For low-voltage and medium-voltage distribution networks (earthing transformers operate for a long time), the impact of no-load loss is obvious, and models with low no-load loss (such as national standard level 1 energy efficiency) should be preferred during selection; for high-voltage/extra-high voltage systems (earthing transformers work for a short time during faults), the proportion of no-load loss is small, and fault tolerance performance can be prioritized. Overall, its annual loss is much lower than that of ordinary power transformers, and the operating cost is relatively low

$5760.00

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Model

JDS-33KV

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