500kVA 11kV Dry-Type Zigzag Grounding Transformer
The Dry-Type Zigzag Earthing/Grounding Transformer 500kVA 11kV is designed to provide an effective neutral grounding solution for medium-voltage power systems. By creating an artificial neutral point, the zigzag transformer limits earth fault currents, stabilizes system voltage, and enhances overall grid safety. Its zigzag winding configuration ensures balanced performance under normal operation while offering low zero-sequence impedance during ground faults.
Featuring a dry-type insulation system, this transformer eliminates the risk of oil leakage and fire hazards, making it ideal for indoor substations and environmentally sensitive installations. The low-loss core design minimizes energy consumption and heat generation, ensuring high efficiency and long service life.
- 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 11/200kV 11/170kV or others
- Standards IEEE, ANSI, NEMA, IEC, GB
- Application industrial plants, renewable energy facilities, and utility distribution networks
- Power Rating 500kVA
- 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
500kVA 11kV Dry-Type Zigzag Grounding Transformer
Technical Specifications
Accessories
| Rated Power | 500kVA | |
| 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
500kVA 11kV Dry-Type Zigzag Grounding Transformer
The 500kVA 11kV Dry-Type Zigzag Earthing Transformer offers extensive electrical customization to meet different grounding and protection requirements. Voltage ratings can be tailored to match system nominal voltages, while impedance values may be adjusted to control earth fault current levels precisely. Customers can specify continuous or short-time fault current ratings according to grid protection schemes. Optional neutral grounding resistors (NGRs) can be integrated to further limit fault currents and coordinate with protection relays. Winding conductor material options include high-purity copper or aluminum, selected based on thermal performance and cost considerations.
From a mechanical and environmental perspective, the transformer can be customized for indoor or sheltered outdoor installation. Insulation class, temperature rise limits, and cooling design are configurable to suit ambient conditions. Low-noise core construction is available for installations near sensitive environments. Enclosure options include open-frame, IP-rated metal enclosures, or ventilated cabinets. Optional monitoring accessories such as temperature sensors, space heaters, and protective relays can be integrated to enhance operational reliability and maintenance efficiency. This flexibility ensures seamless integration into a wide range of medium-voltage systems.
Packing and Shipping
500kVA 11kV Dry-Type Zigzag Grounding Transformer
Packing and shipping of the dry-type zigzag grounding transformer are carefully managed to ensure mechanical protection and insulation integrity throughout transportation. Prior to packing, the transformer undergoes a final inspection and cleaning process to remove dust and moisture. All electrical terminals, grounding points, and exposed insulation surfaces are protected with insulating covers and shock-resistant materials.
The transformer is wrapped with moisture-resistant and dust-proof packaging materials suitable for dry-type equipment. For long-distance transport, additional protective layers are applied to prevent vibration damage. Accessories such as grounding resistors, monitoring devices, and mounting hardware are packed separately in labeled crates to ensure easy identification during installation.
The main unit is secured on reinforced wooden or steel pallets designed to support the transformer’s weight and maintain stability during lifting and transit. Shock-absorbing pads are used to minimize vibration effects during road or sea transportation. All wooden packaging complies with ISPM 15 requirements for international shipping.
Clear handling labels, lifting instructions, and safety warnings are applied to each package. Comprehensive documentation—including packing lists, test reports, manuals, and certificates—is provided to ensure smooth customs clearance and site acceptance. This approach ensures safe delivery and rapid commissioning upon arrival.
The transformer is wrapped with moisture-resistant and dust-proof packaging materials suitable for dry-type equipment. For long-distance transport, additional protective layers are applied to prevent vibration damage. Accessories such as grounding resistors, monitoring devices, and mounting hardware are packed separately in labeled crates to ensure easy identification during installation.
The main unit is secured on reinforced wooden or steel pallets designed to support the transformer’s weight and maintain stability during lifting and transit. Shock-absorbing pads are used to minimize vibration effects during road or sea transportation. All wooden packaging complies with ISPM 15 requirements for international shipping.
Clear handling labels, lifting instructions, and safety warnings are applied to each package. Comprehensive documentation—including packing lists, test reports, manuals, and certificates—is provided to ensure smooth customs clearance and site acceptance. This approach ensures safe delivery and rapid commissioning upon arrival.
32
32 years of industry experience
Manufacturer Test
500kVA 11kV Dry-Type Zigzag Grounding Transformer
Progress Test
Progress testing is conducted throughout the manufacturing process to ensure quality consistency and compliance with design specifications. Incoming materials such as magnetic core steel, winding conductors, and insulation materials are inspected and verified before production. Core assembly inspections focus on lamination alignment, stacking pressure, and dimensional accuracy to ensure optimal magnetic performance.
During winding and insulation processes, inspections verify conductor placement, insulation thickness, and mechanical rigidity. The assembled windings undergo drying and thermal conditioning to remove moisture and stabilize insulation properties. Intermediate electrical tests, including winding resistance and insulation resistance measurements, are performed prior to final assembly.
Enclosure fabrication and surface finishing are inspected to ensure mechanical strength and corrosion resistance. Final assembly checks confirm correct terminal connections and grounding arrangements. All inspection results are recorded to maintain traceability and ensure readiness for factory acceptance testing.
Design Tests
All transformers will be test after finished 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 verifies that the grounding transformer meets technical and contractual requirements. Tests include winding resistance measurement, insulation resistance testing, and impedance verification. Functional tests confirm proper zigzag grounding performance.
Temperature rise tests validate 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.
Mechanical inspections ensure enclosure integrity and terminal strength. Upon completion, a comprehensive FAT report is issued prior to shipment.
Routine Test - Induced Voltage
Purpose of Testing
The purpose of the Induced Voltage test is to simulate the electrical stress that the equipment may encounter under actual working conditions by applying an induced voltage, thereby evaluating the tolerance and stability of the equipment's insulation system. This test helps to detect the insulation performance of the equipment under high voltage conditions and ensure its safety and reliability in operation.
Testing Equipment
Induced Voltage Tester (e.g. OMICRON, Megger, HioKI, etc.)
AC voltage source, commonly 2 kV, 5 kV, 10 kV, or customized according to test requirements.
Environmental thermometer and hygrometer, used to record the temperature and humidity of the environment for appropriate test evaluation.
AC voltage source, commonly 2 kV, 5 kV, 10 kV, or customized according to test requirements.
Environmental thermometer and hygrometer, used to record the temperature and humidity of the environment for appropriate test evaluation.
Pre-Test Preparation
Disconnect all relevant power supplies and ensure that the equipment is properly grounded and discharged.
Check the connection wires and terminals to ensure they are secure and free of contamination.
Test under suitable environmental conditions: relative humidity below 75%, no rain (recommended temperature: 20-30°C).
Check the connection wires and terminals to ensure they are secure and free of contamination.
Test under suitable environmental conditions: relative humidity below 75%, no rain (recommended temperature: 20-30°C).
Test Progress
Connect the Test Instrument:
Connect the test equipment to the appropriate terminals or bushings of the device under test, ensuring that the connections are secure and properly grounded.
Apply Test Voltage:
Select the appropriate induction voltage according to the rated voltage and standard of the equipment.
Connect the test equipment to the appropriate terminals or bushings of the device under test, ensuring that the connections are secure and properly grounded.
Apply Test Voltage:
Select the appropriate induction voltage according to the rated voltage and standard of the equipment.
Measure and Record
Start the test and record the following parameters:
Induced Voltage
Applied Current
Voltage peak, stability and waveform (waveform analysis)
Any abnormal current or voltage changes during the measurement process.
Induced Voltage
Applied Current
Voltage peak, stability and waveform (waveform analysis)
Any abnormal current or voltage changes during the measurement process.
Temperature Correction
The measured induced voltage data is corrected to the reference temperature (usually 20°C) to ensure the accuracy of the test results.
Repeat Testing (if necessary)
If necessary, test different windings (HV, MV, LV) and bushings separately and compare the results at different test points.
Evaluation Criteria (Reference)
Inductive voltage ≤ 1% (Excellent): normally and meets safety standards.
1% < Inductive voltage ≤ 3% (Good): still within acceptable range.
Inductive voltage > 3% : faulty or not meet safety requirements and requires further analysis and repair.
1% < Inductive voltage ≤ 3% (Good): still within acceptable range.
Inductive voltage > 3% : faulty or not meet safety requirements and requires further analysis and repair.
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Used in industrial substations, power plants, and renewable energy facilities to provide neutral grounding, control earth fault currents, and enhance system safety in medium-voltage networks.
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
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What is a Transformer?A transformer is an electrical device used to change the voltage of alternating current (AC). It works on the principle of electromagnetic induction, converting high-voltage current into low-voltage current or low-voltage current into high-voltage current. Transformers are widely used in power transmission, distribution systems, and various electronic devices.
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What are the main uses of a transformer?The main use of a transformer is voltage conversion. Transformers are used in power transmission systems to help transfer electricity from power plants to consumers. In addition, transformers are also used in electronic devices such as chargers, televisions, power adapters, etc., to adjust the voltage to meet the requirements of different devices.
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Do you have UL listed?Yes, our transformer has UL listed. We have exported to America many pad mounted transformer,substation transformer and HV.
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