Powering reliable industrial performance with high-efficiency unit substation transformer design built for reliable industrial power.
01 General
1.1 Project Description
In 2026, a 1000 kVA three-phase unit substation transformer was manufactured in America and delivered to El Salvador for a food processing and cold-storage industrial project, where the customer required long-term operational reliability, stable voltage performance for heavy motor loads, and dependable operation under tropical climate conditions. As the core power conversion equipment between the 23.9 kV utility distribution network and the 480 V industrial utilization system, the unit substation transformer supplies continuous power to refrigeration compressors, industrial ventilation systems, conveyor lines, water pumps, and automated processing equipment operating under 24-hour production conditions.
The supplied unit substation transformer is designed in accordance with IEEE C57.12.36-2007 standards, featuring a rated capacity of 1000 kVA, 23.9 kV primary voltage, 0.48 kV secondary voltage, Dyn1 vector group, ONAN cooling method, mineral oil insulation, copper windings, 5.45% impedance, and 99.15% operating efficiency, allowing the industrial facility to balance energy efficiency, operational stability, and long-term maintenance reliability within a demanding industrial environment.
1.2 Technical Specification
1000kVA unit substation transformer specification and data sheet
| Delivered to | El Salvador |
| Year | 2026 |
| Type | unit substation transformer |
| Standard | IEEE C57.12.36-2007 |
| Rated Power | 1000KVA |
| Frequency | 60HZ |
| Phase | three |
| Cooling Type | ONAN |
| Liquid insulant | Mineral Oil |
| Primary Voltage | 23.9 kV |
| Secondary Voltage | 0.48 kV |
| Vector Group | Dyn1 |
| Winding Material | Copper |
| Impedance | 5.45% |
| Efficiency and Losses Standard | 99.15% |
| Tap Changer | NLTC |
| No, OF TAP POSITION | 5 |
| No Load Loss | 1600W |
| On Load Loss | 11850W |
| Accessories | Standard Configuration |
1.3 Drawings
1000kVA unit substation transformer drawing and nameplate
Winding
02 Manufacturing
2.1 Core
This unit substation transformer adopts a high-efficiency magnetic core designed to reduce no-load losses and control long-term energy consumption in continuous industrial operation. With a no-load loss of only 1600 W and overall efficiency of 99.15%, the core helps limit heat generation inside the tank, which in turn supports slower insulation aging and more stable long-term performance in 24-hour industrial service.
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2.2 Winding
The unit substation transformer uses copper windings to improve conductivity, thermal stability, and mechanical strength under frequent motor starting conditions. In applications such as cold-storage compressors and industrial pumps, load variations and inrush currents are common. The copper design helps the unit substation transformer maintain stable operation under these stresses.
The 5.45% impedance also improves voltage regulation during startup events, reducing excessive voltage drops and supporting stable power delivery to downstream equipment.
2.3 ONAN Cooling System
Considering the hot and humid operating environment in El Salvador, this unit adopts an ONAN oil-immersed self-cooled system using mineral oil and natural circulation. The design is simple but reliable, suitable for long-term industrial operation with low maintenance requirements. Five radiators are installed to improve heat dissipation under continuous load conditions, helping maintain stable oil temperature and protecting insulation performance during sustained operation.
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2.4 Monitoring and Protection Accessories
This unit substation transformer is equipped with standard industrial monitoring and protection accessories to support safe long-term operation. The configuration includes pressure relief devices, vacuum pressure gauge, liquid level indicator, liquid thermometer, and oil sampling facilities.
These components allow operators to monitor internal conditions such as oil level, temperature, and pressure changes, helping detect abnormalities early and reduce the risk of unexpected shutdowns in continuous industrial service.
2.5 Monitoring Instruments with Alarm Contacts
To support unattended operation and remote monitoring, the BESS transformer is equipped with a top oil thermometer, an oil level gauge, and vacuum pressure gauge with alarm contacts. These monitoring devices allow operating signals and abnormal conditions to be transmitted directly to SCADA or BESS control systems, improving operational visibility and protection coordination in energy storage applications.
03 Testing
Testing Standard
| IEEE C57.12.00-2021 | IEEE Standard for General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers ,IEEE |
| IEEE C57.12.90-2021 | IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformer ,IEEE |
Testing Results
04 Packing and Shipping
4.1 Packing
4.2 Shipping
05 Site and Summary
The overall construction of the unit substation transformer is designed for long-term industrial service under demanding operating conditions, combining IEEE-compliant electrical performance with robust mechanical durability and reliable insulation protection.
The sealed oil-filled tank structure, copper winding system, radiator arrangement, grounding configuration, and integrated monitoring accessories together create a unit substation transformer solution capable of supporting continuous industrial operation with reduced maintenance requirements and lower operational risk.
