11kV 1500kVA Zigzag Wiring Earthing Transformer with NGR High Impedance
11kV 1500kVA Zigzag Wiring Earthing Transformer with NGR (High Impedance) is designed to provide a reliable artificial neutral point for medium-voltage power systems where controlled earth fault current is required. Utilizing a zigzag winding configuration, the transformer offers low zero-sequence impedance while maintaining balanced operation during normal conditions. The integrated high-impedance Neutral Grounding Resistor (NGR) effectively limits ground fault current, reducing thermal and mechanical stress on network equipment.
This transformer is engineered for stable performance, high fault withstand capability, and long operational life. The robust insulation system and reinforced windings ensure safe operation under fault conditions, while the optimized core design minimizes losses.
- Primary Voltage Ratings 34.5/33/24/11kV or others
- Secondary Voltage Ratings 480/277V, 400/230V, 380/220V, no LV winding or customized
- H.V. Tap Range ± 2×2.5% HV taps or others
- Type Earth transformer
- BIL 11kV or others
- Standards IEEE, ANSI, NEMA, IEC, GB
- Application utility substations, industrial plants, and renewable energy systems
- Power Rating 1500kVA
- Certificate UL ,CESI
- Cooling Method ONAN, KNAN
- Oil Mineral Oil or FR3
- Opeartion Grounding
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
11kV 1500kVA Zigzag Wiring Earthing Transformer with NGR High Impedance
Technical Specifications
Accessories
| Rated Power | 1500kVA | |
| Rating Primary Voltage | 2.4-34.5kV | |
| Secondary Voltage | 480/277V 400/230V 380/220V Customized |
|
| Frequency | 50/60Hz | |
| Vector Group | ZNd, ZN | |
| Winding Material | Aluminum/Copper | |
| Zero-Sequence Impedance | Customized | |
| Altitude | ≤1,000m or Customized | |
| Color | ANSI 70 Light gray/Munsell 7GY3.29/1.5 or customized etc | |
| Tank material | Mild Steel, 304 Stainless Steel | |
| Insulating Oil Weight | 1000 kg | |
| Total Weight | 4200 kg | |
| Outline Dimensions（L×W×H）in. | 2500×1100×2500（mm) | |
| HV Bushing |
| LV Bushing |
| Tap changer |
| Oil level gauge |
| Oil temperature indicator |
| Pressure relief device |
| CT |
| Lifting hook for complete transformer |
| Name plate |
| Radiators |
| Oil upper filtering valve |
| Oil drain valve with 3/8" sampler |
| Terminal box |
Customization Optional
11kV 1500kVA Zigzag Wiring Earthing Transformer with NGR High Impedance
The 11kV 1500kVA Zigzag Earthing Transformer with NGR can be customized to meet a wide range of grounding philosophies and protection schemes. System voltage levels, rated capacity, and zero-sequence impedance can be adjusted to suit specific network requirements. The Neutral Grounding Resistor is configurable in terms of resistance value, thermal rating, and short-time current withstand duration, allowing precise control of earth fault current magnitude. Customers may select copper or aluminum conductors depending on efficiency expectations, thermal margins, and budget considerations. Continuous and intermittent fault duty ratings can also be customized to align with protection relay coordination and clearing times.
Mechanical and environmental customization ensures adaptability to diverse installation environments. The transformer structure can be designed for indoor substations or sheltered outdoor locations. Insulation class, temperature rise limits, and cooling configuration are adjustable to suit ambient temperature and ventilation conditions. Noise-optimized core designs are available for installations near sensitive areas. Optional accessories include temperature monitoring sensors, grounding current indicators, space heaters, and protective enclosures with varying IP ratings. These customization options ensure seamless integration into existing power systems while enhancing safety, reliability, and long-term operational performance.
Packing and Shipping
11kV 1500kVA Zigzag Wiring Earthing Transformer with NGR High Impedance
Packing and shipping of the zigzag earthing transformer are carried out with strict attention to mechanical protection and insulation integrity. Before packing, the transformer undergoes a final inspection to verify assembly accuracy, terminal alignment, and cleanliness. All exposed electrical connections, grounding terminals, and insulation surfaces are covered with protective caps and impact-resistant materials.
The transformer is wrapped using moisture-resistant and dust-proof packaging suitable for dry-type or oil-filled grounding equipment. For extended transportation or export shipments, additional cushioning and vibration-damping layers are applied. The Neutral Grounding Resistor, control panels, and auxiliary components are packed separately in labeled crates to prevent damage and facilitate on-site installation.
The main unit is secured on reinforced wooden or steel pallets designed to support the transformer’s weight and maintain stability during handling. Shock-absorbing pads reduce vibration during road, rail, or sea transport. All wooden packaging materials comply with ISPM 15 international phytosanitary regulations.
Clear lifting instructions, handling symbols, and safety warnings are displayed on the packaging. Complete shipping documentation—including packing lists, factory test reports, installation manuals, and certificates—is provided to ensure smooth customs clearance and site acceptance. This systematic approach ensures the transformer arrives ready for installation and commissioning.
The transformer is wrapped using moisture-resistant and dust-proof packaging suitable for dry-type or oil-filled grounding equipment. For extended transportation or export shipments, additional cushioning and vibration-damping layers are applied. The Neutral Grounding Resistor, control panels, and auxiliary components are packed separately in labeled crates to prevent damage and facilitate on-site installation.
The main unit is secured on reinforced wooden or steel pallets designed to support the transformer’s weight and maintain stability during handling. Shock-absorbing pads reduce vibration during road, rail, or sea transport. All wooden packaging materials comply with ISPM 15 international phytosanitary regulations.
Clear lifting instructions, handling symbols, and safety warnings are displayed on the packaging. Complete shipping documentation—including packing lists, factory test reports, installation manuals, and certificates—is provided to ensure smooth customs clearance and site acceptance. This systematic approach ensures the transformer arrives ready for installation and commissioning.
32
32 years of industry experience
Manufacturer Test
11kV 1500kVA Zigzag Wiring Earthing Transformer with NGR High Impedance
Progress Test
An alternative progress testing program emphasizes process monitoring and documentation at each production milestone. Raw materials are tracked from receipt through assembly to ensure specification compliance. Core loss measurements and dimensional checks validate magnetic efficiency before coil installation.
Winding operations are monitored for correct tension, insulation overlap, and structural integrity. Drying cycles and thermal treatments are controlled and recorded. Electrical integrity tests confirm insulation health before enclosure installation.
Final inspections verify mechanical stability, grounding configuration, and accessory installation. Comprehensive records support quality assurance prior to FAT.
Design Tests
All transformer will be test after finishing the production, test items as follows:
♦ Insulation Power Factor
♦ Winding Resistance
♦ Impulse Tests
♦ On load Loss Test
♦ No Load Loss Test
♦ Leak Test
♦ DC Insulation Resistance Test
♦ Transformer Turns Ratio/TTR (All Tap Voltages)
♦ Impedance Voltage & Load Loss (Rated Voltage)
♦ Excitation & No-Load Loss (Rated Voltage)
♦ Applied Voltage
♦ Induced Voltage
♦ Lightning Impulse
♦ Insulation Resistance (Rated Voltage)
♦ Temperature Rise
Transformer Factory Acceptance Test
The Factory Acceptance Test validates that the earthing transformer meets contractual and technical requirements. Tests include winding resistance measurement, insulation resistance testing, and impedance verification. Functional tests confirm correct zigzag grounding behavior and NGR performance.
Temperature rise tests verify thermal design, while noise measurements confirm compliance with environmental standards. Visual and dimensional inspections ensure assembly quality. All results are documented in a FAT report for customer approval.
Tests verify high-impedance grounding characteristics, short-time current withstand capability, and insulation strength. Auxiliary devices such as grounding indicators and temperature sensors are functionally tested.
Routine Test - DC Insulation Resistance Test
Purpose of Testing
The purpose of DC insulation resistance testing is to measure the insulation resistance of a device by applying a DC voltage, thereby evaluating the health of the insulation material and the voltage withstand capability of the electrical device. This test helps detect potential insulation aging, moisture or damage, preventing electrical failures in the device.
Testing Equipment
Insulation resistance tester (e.g. Megger, Fluke, Hioki, Klein Tools, etc.)
Voltage source (usually 500V, 1000V, 2500V, or customized according to customer requirements)
Temperature and humidity meter (used to record the ambient temperature and humidity during the test to ensure that the test conditions meet the standard requirements.)
Voltage source (usually 500V, 1000V, 2500V, or customized according to customer requirements)
Temperature and humidity meter (used to record the ambient temperature and humidity during the test to ensure that the test conditions meet the standard requirements.)
Pre-Test Preparation
Make sure the device is properly grounded and fully discharged to prevent residual charge in the device from affecting the test results.
Perform the test under suitable environmental conditions. It is recommended to have a relative humidity below 75%, no rain, and a temperature range of 20-30°C to avoid moisture or temperature fluctuations affecting the test results.
Perform the test under suitable environmental conditions. It is recommended to have a relative humidity below 75%, no rain, and a temperature range of 20-30°C to avoid moisture or temperature fluctuations affecting the test results.
Test Progress
Connect the Test Instrument:
Connect an insulation resistance tester to the high voltage terminal of the device under test and to ground.
Apply Test Voltage:
Select an appropriate test voltage based on the rated voltage of the equipment .
Connect an insulation resistance tester to the high voltage terminal of the device under test and to ground.
Apply Test Voltage:
Select an appropriate test voltage based on the rated voltage of the equipment .
Measure and Record
Start the test and record the following parameters:
Insulation resistance value (MΩ)
Applied voltage
Ambient temperature and humidity during testing
Insulation resistance value (MΩ)
Applied voltage
Ambient temperature and humidity during testing
Temperature Correction
The measured insulation resistance values are corrected to a reference temperature (usually 20°C) for accurate evaluation.
Repeat Testing (if necessary)
Measure different windings (high voltage, medium voltage, low voltage) or each bushing separately, and conduct comparative analysis to ensure the insulation status of all parts.
Evaluation Criteria (Reference)
Insulation resistance ≥ 1000 MΩ (excellent)
500 MΩ ≤ Insulation resistance < 1000 MΩ (good)
100 MΩ ≤ Insulation resistance < 500 MΩ
Insulation resistance < 100 MΩ
500 MΩ ≤ Insulation resistance < 1000 MΩ (good)
100 MΩ ≤ Insulation resistance < 500 MΩ
Insulation resistance < 100 MΩ
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Suitable for utility substations and industrial power systems requiring high-impedance grounding to limit earth fault currents and improve protection coordination in 11kV networks.
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
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