11/0.4kV Dry Type Transformer | Indoor Power Transformer
Discover the reliable 11/0.4kV Dry Type Transformer | Indoor Power Transformer, a safe, oil-free solution designed for efficient medium-to-low voltage conversion in indoor electrical installations. This three-phase dry-type transformer (typically cast resin or vacuum pressure impregnated) features premium low-loss silicon steel cores and high-conductivity copper windings, achieving superior energy efficiency often exceeding 98% and complying with IEC 60076-11 standards. The epoxy resin encapsulation provides excellent moisture resistance, fire self-extinguishing properties (F1 class), minimal partial discharge (<10pC), and robust short-circuit withstand capability. With natural air (AN) cooling and optional forced air (AF) upgrades, it offers low noise operation, Class F/H insulation, and maintenance-free performance in demanding environments. Ideal for step-down from 11kV primary (with ±2×2.5% or wider off-circuit taps) to 0.4kV secondary (Dyn11 vector group standard), this indoor power transformer supports capacities from 100kVA to several MVA, delivering stable, eco-friendly power distribution without oil-related risks.
- Primary Voltage Ratings 11 kV (11000 V) delta or grounded wye
- Secondary Voltage Ratings 0.4 kV (400/230 V) wye
- H.V. Tap Range ± 2×2.5% HV taps or others
- Type Dry type transformer
- BIL 30/95kV
- Standards IEEE, ANSI, NEMA,IEC,GB
- Application commercial buildings, offices, shopping centers
- Power Rating 50kVA - 7500kVA
- Certificate IEC 60076-11, IEC 60076-1, IEC 60076-3, UL 1561
- Cooling Method OA/OF
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
11/0.4kV Dry Type Transformer | Indoor Power Transformer
Technical Specifications
Accessories
| Rated Power | 50kVA- 7500 kVA | |
| Rating Primary Voltage | 11kV | |
| Secondary Voltage | 480/277V 400/230V 380/220V Customized |
|
| Frequency | 50/60Hz | |
| Vector Group | Dyn11,Yyn0,Dyn5 | |
| Winding Material | Aluminum/Copper | |
| Efficiency | As IEEE,Doe 2016,CAS Std or Customized | |
| Impedance Voltage | Nominal 2% or Customized 1.1-5.75% | |
| Altitude | ≤1,000m or Customized | |
| Enclosure material | 304 Stainless Steel | |
|
Cooling |
Natural air (AN); forced air (AF) optional for overload |
|
|
Impedance |
4.0–6.0% (±7.5%) |
|
| HV Bushing |
| LV Bushing |
| Tap changer connector |
| Lifting hook for complete transformer |
| Name plate |
Customization Optional
11/0.4kV Dry Type Transformer | Indoor Power Transformer
The 11/0.4kV Dry Type Transformer offers extensive customization to meet diverse indoor application needs, from commercial facilities to industrial substations. Primary voltage remains standard at 11kV (or 10.5kV variants), with flexible secondary 0.4kV (400V/415V options) and vector groups like Dyn11 for harmonic mitigation or Yyn0 for specific grounding. Capacities range widely (100kVA to 5000kVA+), with copper windings standard for optimal conductivity or aluminum for cost/weight savings. Tap changers include off-circuit ±2×2.5% to ±10% or on-load (OLTC) for automatic voltage regulation under load variations. Insulation upgrades to Class H (180°C) support elevated ambients or overloads, while partial discharge can be limited below 5pC for sensitive environments. Cooling enhancements feature forced air (AF) fans for 40-50% capacity boost, with enclosure protection from IP00 open to IP54/IP55 dust/water-resistant designs including filters or louvers.
Further options encompass integrated temperature sensors (PT100/thermocouples) with digital relays for alarms/trips, anti-vibration mounts reducing noise below 55-65dB, electrostatic shielding for EMI protection, smart monitoring via Modbus/Ethernet for predictive maintenance, and special resin formulations for enhanced fire resistance or chemical/corrosion protection. Seismic bracing, marine-grade finishes, and oversized terminals accommodate high-current or custom installations. These factory-tailored features ensure seamless integration, boosting visibility for "custom 11/0.4kV indoor dry type transformers."
Packing and Shipping
11/0.4kV Dry Type Transformer | Indoor Power Transformer
Packaging the 11/0.4kV Dry Type Indoor Power Transformer prioritizes safeguarding resin windings, core, and accessories during transit. The unit is bolted to a reinforced wooden pallet with anti-vibration isolators, corner braces, and lifting provisions for crane/forklift handling. Terminals, bushings, and sensors receive foam padding and rigid protective caps, while the assembly is wrapped in multi-layer moisture-barrier film and breathable covers. A sturdy, ISPM 15-compliant wooden crate fully encloses it, reinforced with internal supports, desiccant packs, humidity indicators, and shock/tilt recorders to monitor conditions and ensure dry-type integrity upon arrival.
Shipping solutions provide secure, flexible delivery for this indoor transformer worldwide. Ocean freight in 20ft/40ft containers offers economical transport with secure bracing, typically 20-50 days to ports. Air freight expedites urgent needs in 5-12 days. Domestic/regional trucking uses enclosed trailers with weather protection and tie-downs for safe movement. Full-value insurance covers risks end-to-end.
Export documentation includes invoices, packing lists, origin certificates, test reports, and IEC compliance declarations for efficient customs. Sustainable practices feature recyclable crates and optimized routing to reduce emissions. Clients access real-time GPS tracking with alerts and dedicated support.
Arrival assistance offers optional unpacking supervision, insulation checks, and packaging recycling to speed commissioning. Bulk orders benefit from consolidated shipments and phased delivery. This process guarantees flawless arrival, enhancing SEO for "reliable 11/0.4kV dry type transformer logistics."
The transformer is mounted on a reinforced wooden pallet or steel skid designed for forklift and crane handling, wrapped in multi-layer stretch film and moisture-barrier material. Desiccant packs are included to control humidity, critical for cast-resin units that must remain dry before energization. The entire unit is then placed in a sturdy export-grade wooden crate (ISPM-15 heat-treated) with foam corner protectors, wooden bracing, and steel strapping for stability. Clear markings include gross/net weight, center of gravity, lift points, dimensions (approx. 2.0–2.6 m L × 1.4–1.8 m W × 2.0–2.4 m H), and handling instructions (“Fragile – Electrical Equipment – No Tipping”).
Shipping solutions provide secure, flexible delivery for this indoor transformer worldwide. Ocean freight in 20ft/40ft containers offers economical transport with secure bracing, typically 20-50 days to ports. Air freight expedites urgent needs in 5-12 days. Domestic/regional trucking uses enclosed trailers with weather protection and tie-downs for safe movement. Full-value insurance covers risks end-to-end.
Export documentation includes invoices, packing lists, origin certificates, test reports, and IEC compliance declarations for efficient customs. Sustainable practices feature recyclable crates and optimized routing to reduce emissions. Clients access real-time GPS tracking with alerts and dedicated support.
Arrival assistance offers optional unpacking supervision, insulation checks, and packaging recycling to speed commissioning. Bulk orders benefit from consolidated shipments and phased delivery. This process guarantees flawless arrival, enhancing SEO for "reliable 11/0.4kV dry type transformer logistics."
The transformer is mounted on a reinforced wooden pallet or steel skid designed for forklift and crane handling, wrapped in multi-layer stretch film and moisture-barrier material. Desiccant packs are included to control humidity, critical for cast-resin units that must remain dry before energization. The entire unit is then placed in a sturdy export-grade wooden crate (ISPM-15 heat-treated) with foam corner protectors, wooden bracing, and steel strapping for stability. Clear markings include gross/net weight, center of gravity, lift points, dimensions (approx. 2.0–2.6 m L × 1.4–1.8 m W × 2.0–2.4 m H), and handling instructions (“Fragile – Electrical Equipment – No Tipping”).
32
32 years of industry experience
Manufacturer Test
11/0.4kV Dry Type Transformer | Indoor Power Transformer
Progress Test
During core-coil encapsulation progress of the 11/0.4kV dry type transformer, resin penetration and void detection are validated through multiple vacuum cycles and partial discharge measurements to guarantee superior dielectric strength. Post-encapsulation high-voltage leads routing, bracing, and clearance distances are verified to withstand impulse and power-frequency withstand requirements. After enclosure assembly, preliminary insulation resistance and dielectric withstand tests prove overall system robustness. Temperature sensor, fan (if AF), and alarm circuit progress includes repeated functional cycling for operational reliability. Paint dry film thickness and adhesion are measured for long-term environmental protection. Final pre-acceptance inspections cover nameplate engraving accuracy, labeling compliance, enclosure grounding, and overall cosmetic/structural quality. Cumulative progress testing facilitates real-time corrective actions, building confidence for smooth factory acceptance and dependable long-term indoor operation.
Design Tests
All transformer will be test after finished the production, test items as below:
♦ 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
♦ Insulation Resistance (Rated Voltage)
♦ Temperature Rise
Transformer Factory Acceptance Test
Induced voltage test at double frequency stresses inter-turn and layer insulation with sensitive partial discharge monitoring to confirm corona-free operation. No-load loss and excitation current are measured at rated voltage to validate core performance against efficiency targets. Impedance/load loss at rated current is determined to verify percentage impedance, copper losses, and regulation characteristics. Temperature rise test (optional witnessed heat run) confirms compliance with class rise limits under rated load. Sound level measurement verifies compliance with specified dB limits. Functional verification operates tap changer through all positions, checks temperature sensors, fan controls (if AF), and alarms. Certified test reports with traceable calibration data and customer witness provisions (if requested) document all results, confirming the transformer exceeds efficiency, dielectric strength, safety, and performance requirements for reliable dry-type service.
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)
nsulation 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
Test standard
IEEE C57.12.01 & IEEE C57.12.91 (Dry-Type)
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Widely deployed in commercial office buildings, retail malls, hotels, schools, hospitals, and high-rise residential towers for safe indoor step-down from 11 kV medium-voltage to 400/230 V low-voltage distribution. Ideal for fire-sensitive, noise-restricted, or space-constrained locations where oil-filled transformers are prohibited by building codes, insurance requirements, or environmental regulations.
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
Product Packaging
Transformers Packaging (1)
Transformers Packaging (2)
Transformers Packaging (3)
Transformers Packaging (4)
Transformers Packaging (5)
Transformers Packaging (6)
Transformers Packaging (7)
Transformers Packaging (8)
Related Products
100kVA Single Phase Pad Mounted Transformer
The 100 kVA Single Phase Pad Mounted transformer adheres to a compartmental-type structure in line with IEEE Std C57.12.28 or IEEE Std C57.12.29 standards. It consists of a tank housing high-voltage and low-voltage cable terminating compartments, thoughtfully positioned side by side along one face of the transformer tank. In this configuration, the high-voltage compartment, fitted with two internally connected high-voltage bushing wells and inserts, a 4-position loadbreak switch, a 5-position tap changer switch, and a bayonet fuse, is situated alongside the low-voltage compartment featuring three stud L.V bushings and an oil level gauge.
121kV Oil-Immersed High-Voltage Power Transformer
The 121kV Oil-Immersed High-Voltage Power Transformer is designed to provide stable, efficient, and long-term power transformation for transmission networks and high-voltage substations. Utilizing high-quality silicon steel cores and precision-wound copper conductors, the transformer achieves low no-load losses, strong short-circuit withstand capability, and excellent thermal stability. The oil-immersed insulation and cooling system ensures effective heat dissipation, supporting continuous operation under heavy-load and fluctuating grid conditions. Its reinforced tank structure, advanced insulation system, and outdoor-rated protection design enable reliable performance in harsh climates and demanding environments. Manufactured in accordance with IEC, IEEE, and ANSI standards, this transformer is widely applied in utility grids, industrial power systems, and infrastructure projects requiring high reliability, safety, and long service life.
160 kVA Three Phase Cast Resin Dry Type Transformer Low Loss Energy Efficient
The 160 kVA Three Phase Cast Resin Dry Type Transformer Low Loss Energy Efficient is a state-of-the-art, maintenance-free power solution engineered for indoor installations where safety, reliability, and sustainability are paramount. Encased in high-quality epoxy resin under vacuum pressure, its windings deliver outstanding moisture resistance, superior partial discharge performance, and fire-retardant self-extinguishing properties without flammable liquids. Utilizing premium grain-oriented silicon steel cores and optimized conductor designs, this transformer achieves significantly reduced no-load and load losses, attaining high efficiency levels often exceeding 98.5% and complying with stringent energy regulations. With natural air (AN) cooling, low acoustic emissions below typical 58-62 dB, and Class F or H insulation, it ensures stable operation in harsh indoor environments. Fully compliant with IEC 60076-11, this compact, eco-conscious dry-type unit supports primary voltages like 10kV/11kV/20kV/35kV stepping down to 0.4kV or custom secondaries, making it ideal for modern, green power distribution networks.
150kVA Single Phase Pole Mounted Transformer
NPC ELECTRIC'S 150kVA single phase pole mounted transformer is engineered for superior performance in overhead electrical distribution networks. This robust unit efficiently steps down high-voltage primary inputs, such as 13.8kV or 24.94kV, to secondary voltages like 120/240V or 277V, ensuring safe and reliable power delivery. Built with high-permeability toroidal cores and precision-wound copper conductors, it minimizes energy losses and enhances durability. Compliant with DOE-2016 efficiency standards and featuring a NEMA 3R-rated enclosure, this transformer withstands harsh environmental conditions while providing quiet operation. Ideal for utilities seeking long-term reliability, it includes protective features like surge arrestors and pressure relief valves to safeguard against overloads and faults. With a 65°C temperature rise rating and ONAN cooling, it handles diverse loads without compromising efficiency.
500kVA Three Phase Pad Mounted Transformer
The 500kVA three-phase pad transformer is an efficient and sturdy power equipment designed for commercial, industrial and distribution systems. It has a compact design and a protective casing that meets NEMA 3R or higher standards. It is suitable for various outdoor environments and can effectively resist external factors such as weather, dust and moisture. It can meet the power needs of different regions and has a variety of optional functions, such as load regulation and temperature control systems, to further improve its operating efficiency and safety. The built-in protection device can effectively prevent overload, short circuit and other faults to ensure the safe and reliable operation of the power system.
37.5kVA Single Phase Pad Mounted transformer
The 37.5kVA Single Phase Pad Mounted transformer with high voltage (HV) specifications of 24.94GRDY/14.4 kV and low voltage (LV) of 240/120V. At its core lies a robust tank, constructed from resilient alloy 304 stainless steel, guaranteeing longevity even in the harshest conditions. The HV and LV windings, equally critical components, are meticulously crafted from high-quality aluminum to ensure unwavering performance.FAQ From Customers
-
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.
-
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.
-
Do you have UL listed?Yes, our transformer has UL listed. We have exported to America many pad mounted transformer,substation transformer and HV.
Welcome your inquiry
Honesty, Integrity, Frugality, Activeness and Passion