Introduction
SCOTECH’s oil-immersed distribution transformers play an indispensable role in power systems, facilitating electrical energy transfer between circuits via electromagnetic induction to convert high-voltage transmission power into low-voltage electricity suitable for end users. As a crucial link connecting power generation and consumption, they are widely applied in primary and secondary power distribution circuits, effectively preventing power overloads and electrical surges to ensure stable system operation.
Designed with modularity, SCOTECH’s distribution transformers allow for easy customization to meet clients’ specific requirements regarding voltage, load, and environmental conditions, ensuring optimal performance across diverse application scenarios. Moreover, their production strictly adheres to multiple international standards such as ANSI/IEEE, CSA, NEMA, DOE, AS, NZS, and EN, guaranteeing global compatibility and interchangeability.
Construction
Example Drawings
2000 kVA distribution transformer diagram drawing and size.
Manufacturing
4.1 Core
SCOTECH’s distribution transformer cores are crafted using high-quality cold-rolled silicon steel sheets, integrated with advanced production techniques. Each sheet undergoes precise cutting, and the cores feature a step-lap joint design in semicircular or oval configurations to optimize the cross-sectional structure. This thoughtful design not only enhances magnetic flux efficiency to the fullest but also markedly reduces no-load losses and operational noise, ensuring the transformer operates efficiently, safely, and quietly. For scenarios with stringent energy efficiency and noise control demands, amorphous alloy material options are also available, enabling the cores to deliver exceptional performance across diverse environments.
4.2 Winding
SCOTECH’s distribution transformer windings are constructed with high-grade copper or aluminum, engineered to withstand intense electrical and mechanical stresses. The low-voltage windings adopt an advanced design, which minimizes thrust forces during short circuits and integrates with insulating layers to enhance overall durability. High-voltage windings are built directly over the low-voltage coils, leveraging advanced insulation materials and precise tension control to form compact, robust structures that meet the requirements of modern distribution grids.
Integrated oil circulation channels ensure efficient cooling, while the well-arranged primary and secondary coils optimize operational performance and reduce energy losses. This design approach guarantees reliable and long-lasting performance across a range of electrical applications.
4.3 Tank
SCOTECH’s distribution transformer tanks are constructed from high-quality corrugated cold-rolled steel, engineered to withstand mechanical and thermal stresses encountered during transportation and operation. Each tank features a reinforced base that facilitates optimal heat dissipation, and after welding, rigorous leak-tightness testing is conducted to ensure dependable performance.
For corrosion resistance, an eco-friendly water-based coating is applied, paired with an immersion painting process and hot-dip galvanization to boost durability. The tanks are available in hermetically sealed designs or with expansion systems to accommodate volume changes in the insulating liquid, while integrated oil circulation channels enable efficient cooling.Through advanced engineering and meticulous manufacturing, these transformer tanks deliver reliable performance and long service life across diverse electrical distribution environments.
Components
Function: A protective device is used to detect internal faults such as insulation failure, overheating, or arcing.
Operation: Triggers an alarm for minor gas accumulation (due to slow faults) and trips the transformer in case of sudden oil flow (indicating severe faults).
Application: Primarily used in transformers with conservators.
Function: Provides a secure connection point for grounding the transformer tank and core to prevent electrical hazards.
Importance: Ensures safety by dissipating fault currents and static charges to the earth.
Function: Insulates and connects the high-voltage winding to the external power line.
Design: Made of porcelain or composite material, rated for the system voltage (e.g., 11kV, 33kV).
Features: May include capacitive grading for even voltage distribution.
Function: Reinforced hooks or lugs welded to the transformer tank for safe lifting during installation or maintenance.
Safety: Designed to withstand the transformer’s total weight with a safety factor.
Function: Connects the low-voltage winding (e.g., 400V, 230V) to the distribution network.
Material: Typically porcelain or polymer, with lower insulation requirements than HV bushings.
Function: Provides the connection point for the neutral terminal of the transformer’s LV or HV winding.
Grounding: Often linked to the grounding system for fault current return.
Function: Monitors the insulating oil level inside the conservator or tank.
Types:
Magnetic-type with float mechanism.
Transparent tube with marked min/max levels.
Alarm: May include contacts to signal low or high oil levels.
Function: Allows the collection of oil samples for testing (e.g., dielectric strength, moisture content, DGA).
Location: Positioned at the bottom or side of the tank for easy access.
Function: Measures the top oil temperature to prevent overheating.
Features:
Dial or digital display.
Adjustable alarm/trip contacts for temperature thresholds.
Function: Houses a traditional thermometer for manual oil temperature measurement.
Usage: Serves as a backup or secondary check to the OTI.
Function:
Allows adjustment of the transformer’s voltage ratio by changing the number of active turns in the winding.
Used to compensate for variations in input voltage or to match system requirements.
Key Features:
Manual Operation: Must be adjusted when the transformer is de-energized (off-circuit).
Typical Tap Range: Usually provides ±5% to ±10% adjustment in 2.5% steps (e.g., ±2×2.5% or ±4×2.5%).
Tests
Routine tests
1. Measurement Insulation Resistance
2. Check of Voltage Ratio and Vector Group
3. Measurement of winding direct resistance
4. Separate-Source Power-Frequency Voltage Withstand Test
5. Induced Overvoltage Withstand Test (ACSD)
6. Measurement of no-load loss and no-load current
7. Measurement of Impedance Voltage and Load Losses
Type tests
1.Temperature-rise test
2.Dielectric type test
Special tests
1.Measurement of zero-sequence impedance on three-phase transformer
2.Short-circuit withstand test
3.Determination of sound levels
4.Measurement of the harmonics of the no-load current
Applications
• Steps down medium voltage (e.g., 11 kV, 33 kV) to low voltage (e.g., 400/230 V) for residential, commercial, and industrial use.
• Installed in substations, pole-mounted units, or pad-mounted enclosures.
• Provides safe voltage levels for homes, offices, shopping malls, etc.
• Commonly used in urban and rural overhead or underground distribution systems.
• Dedicated power supply for factories, mines, petrochemical plants, etc.
• Supports heavy machinery, production lines, and industrial lighting.
• Used in solar farms and wind power plants to adjust voltage for grid compatibility.
• Enables off-grid or hybrid microgrid systems.
• Ensures stable power for critical facilities like hospitals, schools, airports, and metro systems.
• Powers street lighting and traffic signal networks.
Supplies electricity to rural areas for water pumps, greenhouses, and processing equipment.
Provides power for construction sites, outdoor events, or emergency recovery.
Often paired with mobile or portable transformers.
• Uninterruptible Power: Provides stable voltage conversion for servers, storage, and networking equipment.
• Redundancy: Often paired with backup systems (UPS, generators) to ensure 24/7 uptime.
Our advantages
1. High Efficiency and Energy Savings
- Low-Loss Design: Utilizes high-permeability silicon steel (e.g., high-grade grain-oriented silicon steel) and precision winding technology to significantly reduce no-load loss and load loss, complying with international efficiency standards (e.g., IEC 60076, DOE 2016).
- High Efficiency Ratings: Meets efficiency standards, helping customers reduce long-term electricity costs.
2. Superior Reliability
- Premium Materials: Features high-temperature-resistant insulation materials (e.g., Nomex) and fully sealed tank construction to prevent oxidation and moisture ingress, extending service life.
- Rigorous Testing: Validated through short-circuit withstand, lightning impulse, and temperature rise tests to ensure stable operation under harsh grid conditions.
- Strong Short-Circuit Resistance: Optimized winding structure and electromagnetic design minimize failure risks from overloads or grid fluctuations.
3. High Customization Flexibility
- Tailored Solutions: Supports customized voltage level, capacities, installation type, and adaptations for extreme environments (high altitude, salt fog, extreme temperatures).
- Smart Integration: Optional real-time monitoring systems (temperature, oil level, load) and remote communication (IoT) for smart grid compatibility.
4. Outstanding Cost Efficiency
- Low Total Cost of Ownership (TCO): High-efficiency design reduces energy waste, offering lower lifecycle costs than industry averages.
- Fast Delivery & Support: Global supply chains and localized service teams ensure timely delivery, along with installation, commissioning, and maintenance training.
5. International Certifications & Compliance
- Certified Quality: Complies with ISO 9001, CE, UL, and SGS certifications, meeting IEC, IEEE, ANSI, GB, and other global grid standards.
6. Wide Application Range
- Suitable for industrial/commercial power distribution, renewable energy (solar/wind integration), and critical infrastructure (hospitals, data centers, rail transit), adapting to diverse load conditions.
