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Views: 0 Author: Site Editor Publish Time: 2026-08-17 Origin: Site
During technical reviews for renewable energy projects in the Middle East, we have noticed a common situation:
In many technical specifications, parameters such as capacity, voltage level, impedance, and connection method are clearly defined. However, when it comes to loss requirements, there is often only one statement — “Comply with the requirements of IEC 60076.”
From a compliance perspective, there is nothing wrong with this requirement. However, from the perspective of a transformer’s electricity cost over 20 years of operation, the level of losses directly affects the project’s overall profitability.
In recent years, countries such as Saudi Arabia, the UAE, and Qatar have continued to develop large numbers of photovoltaic power plants, industrial parks, and grid upgrade projects.
These projects share several common characteristics:
Long operating cycles;
High annual operating hours;
High ambient temperatures;
High equipment maintenance costs.
Once a transformer is installed, it is typically expected to operate for 20 years or more. The losses generated every day accumulate year after year, creating a significant long-term cost impact.
Therefore, transformer selection should not focus only on the initial purchase price. The two key parameters — no-load loss and load loss — must be carefully analyzed and calculated.
During technical support for Middle East projects, the engineering team at Zisheng Electric treats transformer loss performance as a key evaluation factor.
Below, we summarize the practical situations and approaches we have encountered in actual projects.
A transformer operates through electromagnetic induction to step voltage up or down. During this process, the core experiences magnetization losses, the windings experience resistance losses, and leakage flux creates additional losses. The input electrical energy can never be converted into output power at 100% efficiency — the difference is the transformer loss.
According to IEC 60076, transformer losses are mainly divided into two categories:
No-load Loss
Load Loss
The differences between them are explained clearly in the following table:
Item | No-load Loss | Load Loss |
|---|---|---|
Cause | Core hysteresis loss and eddy current loss | Winding resistance loss and stray loss |
Operating Condition | Exists as soon as the transformer is energized | Occurs only when the transformer carries load |
Variation Pattern | Basically remains constant | Changes with load current |
Main Influencing Factors | Core material, magnetic flux density design, manufacturing process | Conductor material, winding structure, current level |
Optimization Direction | Reduce core losses | Reduce winding losses |
In simple terms:
No-load loss determines how much electricity a transformer consumes when it is energized but not doing useful work.
Load loss determines how efficiently the transformer performs when it is actually carrying load.
During transformer selection, no-load loss and load loss cannot be evaluated together as a single value because they correspond to completely different operating conditions.
No-load loss refers to the loss measured when rated voltage is applied to the primary side while the secondary side is open-circuited without any load connected.
Many engineers overlook an important fact:
A transformer does not consume electricity only when it is supplying loads. As long as the high-voltage side remains energized, the magnetic field inside the core continues changing, and losses continue to occur.
This characteristic is especially important for photovoltaic projects.
During the daytime, solar power plants generate electricity, and transformers step up the voltage for power transmission.
At night, when the solar panels stop generating electricity, the step-up transformers are usually still kept energized.
With 365 days per year and 24 hours per day, no-load losses continue accumulating without interruption.
If these losses are not included in the project financial model, the economic evaluation of the project may be inaccurate.
The core is the heart of the transformer’s magnetic circuit, and its material performance directly determines the level of no-load loss.
Currently, high-efficiency transformers widely use low-loss cold-rolled grain-oriented silicon steel sheets.
When selecting core materials, key factors include:
Silicon steel sheet grade;
Specific loss value;
Magnetic performance parameters;
Material batch consistency.
In high-temperature environments such as the Middle East, reducing core losses not only saves electricity but also reduces internal heat generation, which improves cooling performance and extends transformer service life.
The design of magnetic flux density requires careful balance.
If the magnetic flux density is designed too high:
Core losses increase;
Temperature rise increases;
Noise levels become higher.
If the magnetic flux density is designed too low:
The core size must be increased;
Material costs rise.
In engineering practice, the goal is to find the right balance between:
Efficiency;
Cost;
Reliability.
There is no absolutely perfect design value — only the most suitable solution for a specific project.
Even the best design drawings are meaningless if manufacturing control is insufficient.
Details such as:
Lamination alignment accuracy;
Joint structure design;
Whether the core is damaged during processing;
directly affect magnetic flux distribution.
Therefore, no-load loss is not only designed — it is also manufactured.
Load loss occurs when the transformer operates under load. It mainly consists of three components:
Winding resistance loss (copper loss);
Conductor eddy current loss;
Additional losses caused by leakage flux.
Among these, copper loss is the dominant component.
Unlike no-load loss, load loss changes with operating current and is proportional to the square of the current.
In other words, as the transformer approaches full-load operation, load losses increase much faster.
The operating conditions of renewable energy projects in the Middle East amplify the impact of load losses.
Photovoltaic projects operate at high output during the daytime.
Large-scale solar power plants generate high output during daylight hours, keeping transformers under high-load conditions for extended periods.
Under these conditions:
Higher load losses generate more heat;
Winding temperatures increase accordingly;
Thermal stress on the transformer becomes more significant.
Industrial projects operate continuously throughout the year.
Industrial parks, oil and gas facilities, and manufacturing plants in the Middle East often run continuously with relatively stable loads and extremely high equipment utilization rates.
Under such operating conditions, even a small reduction in load losses can create significant differences in annual electricity costs over the transformer’s service life.
Summer temperatures of 50°C are common in many parts of the Middle East.
High temperature itself does not change how transformer losses are generated, but it has a significant impact on heat dissipation performance.
The logical chain is as follows:
Loss generation → Heat accumulation → Increased equipment temperature rise → Accelerated aging of insulation materials → Reduced equipment service life
There is one easily overlooked detail: the temperature rise limits of transformers are defined based on a reference ambient temperature. For example, many temperature rise limits in IEC standards are based on the assumption that the ambient temperature does not exceed 40°C.
Once the actual ambient temperature exceeds this reference value, the available temperature rise margin of the transformer is reduced.
For example:
A transformer operating at 40°C ambient temperature has a winding temperature rise limit of 65K. Its actual winding temperature is therefore:
40°C + 65K = 105°C
If the same transformer is installed in a 50°C environment:
50°C + 65K = 115°C
The thermal class of the insulation material has not changed. This means the actual service life will be shorter than the original design expectation.
The issue is not that the transformer losses themselves become higher. Instead, the same amount of loss becomes more difficult to dissipate in a high-temperature environment, causing greater thermal stress on the insulation system.
During technical reviews for Middle East projects, we never make decisions based only on laboratory loss data measured under normal ambient conditions.
The evaluation must consider:
Actual project ambient temperature;
Cooling method;
Temperature rise margin;
Long-term operating conditions.
A transformer that performs well in a 40°C environment may require a completely different thermal verification when installed in a 50°C environment.
This is why Middle East projects cannot simply adopt standard designs based on normal environmental conditions. Dedicated temperature rise design is required.
Transformer losses are not an isolated number. They must be evaluated together with:
Project operating conditions;
Local electricity prices;
Load curves;
Equipment lifecycle.
During technical reviews for renewable energy and industrial projects in the Middle East, we focus on two key aspects:
Different projects have different priorities:
Photovoltaic power plants:
Focus more on long-term energy generation benefits.
Industrial projects:
Focus more on continuous operating costs.
Grid projects:
Focus more on overall system efficiency.
During the technical clarification stage, the following requirements must be clearly defined:
Maximum allowable no-load loss;
Maximum allowable load loss;
Maximum allowable total loss;
Whether the transformer meets the required energy efficiency level.
Many large renewable energy projects now specify guaranteed loss values directly during the tender stage and require suppliers to provide calculation methods and supporting documentation.
If a supplier only provides a total loss value but cannot clearly separate no-load loss and load loss, we usually request further clarification.
Different loss structures can result in significantly different long-term operating performance.
Loss evaluation cannot be separated from actual load conditions.
Take a photovoltaic step-up transformer as an example:
Daytime load: 80%–100%;
Nighttime load: close to zero.
No-load losses occur continuously throughout the year, while load losses are mainly concentrated during daytime power generation hours.
For an industrial project:
Operation may continue 24 hours a day, 365 days a year;
Load variation may be relatively small.
The two projects may use transformers with the same capacity, but the optimal loss design strategy can be completely different.
During the selection stage, we always obtain:
Annual average load factor;
Peak load operating hours;
Continuous operating hours;
before evaluating the appropriate balance between no-load loss and load loss.
The purchase price is only part of the initial investment.
For electrical equipment designed to operate for more than 20 years, the lifecycle cost is the more important figure.
Lifecycle Cost = Initial Purchase Cost + Installation & Commissioning Cost + Energy Loss Cost + Maintenance Cost + Downtime Loss
Among these, operating losses are a continuous expense that occurs every day.
A simple calculation:
1kW reduction in no-load loss:
→ 8,760 operating hours per year
→ Annual energy saving: 8,760kWh
→ 20-year cumulative saving: 175,200kWh
For a large power plant using dozens of transformers, the total energy savings can become very significant.
This is why large-scale projects are increasingly willing to invest more upfront in low-loss transformer designs.
Load loss is directly related to operating load.
For example, a 2500kVA transformer operating continuously at 80% load can benefit from:
Optimized winding structure;
Increased conductor cross-sectional area;
Reduced current density.
Even a small reduction in load loss can generate considerable electricity savings over long-term high-load operation.
Especially in Middle East projects, where electricity costs and annual operating hours are significant, the payback period for loss optimization can be relatively short.
Whether the loss values provided by a supplier can be trusted depends on whether the factory tests are strictly carried out according to the standards.
IEC 60076 clearly specifies the test methods for no-load loss and load loss:
No-load loss test is carried out with the secondary side open-circuited and rated voltage and rated frequency applied to the primary side. The test measures no-load loss and no-load current, verifying the performance of the core material and the magnetic circuit design.
Load loss test is carried out by applying a test current to simulate the rated load condition. The test measures load loss and short-circuit impedance, verifying the winding resistance and conductor connection quality.
For Middle East projects, the temperature rise test is one of the tests that cannot be skipped.
All losses are eventually converted into heat. If the heat dissipation design cannot keep up, even excellent loss data is meaningless.
When reviewing temperature rise test reports, we pay special attention to whether the simulated test ambient temperature covers the actual extreme temperatures at the project site.
If the factory test report only includes temperature rise testing under a 40°C ambient condition, while the project site can reach 50°C in summer, the report can only be used as a reference and cannot serve as the final acceptance basis.
For the operating characteristics of the Middle East, including high temperature, high load, and long-term operation, we usually optimize transformer design in four key areas during the project design stage:
Select low-loss silicon steel sheet grades, properly control magnetic flux density, and optimize core joint structures — reducing no-load losses.
Control current density within an economical range, optimize conductor cross-sectional area, and improve winding arrangement design — reducing load losses.
Select appropriate cooling methods according to project conditions and installation requirements, including:
ONAN oil-immersed natural cooling;
ONAF oil-immersed forced air cooling;
Forced oil circulation cooling.
For desert photovoltaic projects, additional considerations are required, including high ambient temperature, heat dissipation space, and the impact of sand and dust on ventilation openings.
Demand for high-efficiency equipment in Middle East renewable energy projects continues to increase.
Many large-scale tenders now directly include requirements for:
High-efficiency transformers;
Low-loss design;
Lifecycle cost evaluation.
Based on recent tender requirements, low losses and lifecycle costs are becoming increasingly important evaluation criteria for transformer selection.
1. Lessons Learned from a Qatar Project
In 2025, we supported transformer supply for a 50MW photovoltaic power plant project in Qatar.
The technical specification clearly defined the no-load loss requirements. We selected a transformer that met the IEC standard requirements, and all factory tests passed successfully.
However, after the equipment was transported to the site and installed, during the first week of full-load operation in summer, the oil temperature rise approached the alarm limit continuously for three days.
After on-site investigation, we identified the issue:
The "50°C ambient temperature" stated in the technical specification was only a numerical value. Under strong desert sunlight, the surface temperature of the pad-mounted transformer enclosure facing south was significantly higher than 50°C.
The radiator installation position also mattered.
Radiators installed on the shaded side performed normally, but when installed on the sun-facing side, heat dissipation efficiency was significantly reduced. In this project, part of the radiator arrangement happened to be located on the south-facing side.
The final solution included:
Installing a sunshade structure on top of the transformer enclosure;
Changing the direction of the south-facing radiators with a guide cover.
These two modifications required ten days of additional work, resulting in considerable extra labor and material costs.
After this adjustment, we added the following items as mandatory checks in future Middle East project reviews:
Site installation orientation;
Solar radiation conditions;
Wind direction conditions.
This experience also led us to completely revise our Middle East project review process.
We no longer evaluate only loss values. We now include:
Temperature rise margin;
Cooling system design;
Installation orientation;
as mandatory review items.
Zisheng Electric has long provided transformer solutions for renewable energy, power grid, and industrial projects. The characteristics of the Middle East market are clear:
High temperature;
Sand and dust conditions;
Long-term continuous operation.
During transformer design, we do not only consider capacity and voltage. The following factors must be reviewed together:
Loss performance;
Temperature rise level;
Cooling system design;
Insulation system;
Environmental adaptability.
2. Saudi Arabia Photovoltaic Project
Saudi Arabia experiences strong solar radiation and high ambient temperatures in summer.
Based on the lessons learned from Qatar, we performed thermal simulation analysis earlier during the technical proposal stage.
The project adopted:
Low-loss core design to reduce no-load losses below tender requirements;
Cooling structure specifically verified for extreme local temperatures;
Sufficient temperature rise margin.
With sufficient technical evaluation at the early stage, the equipment can maintain stable operation under high-temperature field conditions.
3. UAE Industrial Project
Industrial loads operate continuously, creating higher requirements for load loss control.
Through optimization of:
Winding design;
Conductor cross-sectional area;
we reduced load losses below the owner’s target value.
At the same time, industrial facilities also have noise requirements, which were considered during the design stage.
Some people ask:
Is lower no-load loss always better?
From a technical perspective, lower losses do save electricity. However, transformer design must consider the balance between:
Manufacturing cost;
Equipment size.
After losses are reduced to a certain level, further reduction requires significantly higher investment.
Engineering design aims for a reasonable balance, not simply the lowest possible value.
Another common question:
Why do renewable energy projects pay so much attention to transformer losses?
Renewable energy projects typically have:
Long operating cycles;
High annual operating hours.
Especially for photovoltaic projects, although power generation stops at night, transformers usually remain energized. No-load losses continue 24 hours a day.
Over long operating periods, the impact on project return on investment cannot be ignored. This is often underestimated during the early project stage.
Another question:
Do Middle East projects always require low-loss transformer designs?
It depends on the specific project conditions.
If the project has:
Long operating hours;
High local electricity costs;
Large transformer capacity;
the additional investment in low-loss design can often be recovered quickly through energy savings.
We usually help owners perform a simple payback period analysis, using actual data to support decision-making rather than applying a universal approach.
The final frequently asked question:
How can we determine whether supplier loss data is accurate or exaggerated?
Three key points should be checked:
Whether testing is performed according to IEC 60076 standards;
Whether complete factory test reports are available for review;
Whether the supplier has actual operating data from similar projects.
Loss data should not be evaluated only based on numbers printed in quotation documents. It must be assessed together with:
Testing capability;
Manufacturing experience;
Actual project performance.
Transformer losses may appear to be just a few figures in a technical specification sheet, but in reality, they are directly related to:
Equipment operating efficiency;
Project lifecycle economics;
Long-term power supply reliability.
For renewable energy, grid, and industrial projects in the Middle East, factors such as:
High-temperature environments;
Long operating cycles;
Increasing energy efficiency requirements;
are continuously increasing the importance of transformer loss control.
From core material selection to winding optimization design, from factory test verification to on-site temperature rise validation, every stage affects the total cost throughout a 20-year operating period.
Zisheng Electric designs and manufactures transformers according to the IEC 60076 series of standards while making targeted adjustments based on the actual environmental conditions and operating requirements of each project location.
Our product portfolio includes:
Oil-immersed transformers;
Dry-type transformers;
Conclusion
Transformer losses may appear to be just a few figures in a technical specification sheet, but in reality, they are directly related to:
Equipment operating efficiency;
Project lifecycle economics;
Long-term power supply reliability.
For renewable energy, grid, and industrial projects in the Middle East, factors such as:
High-temperature environments;
Long operating cycles;
Increasing energy efficiency requirements;
are continuously increasing the importance of transformer loss control.
From core material selection to winding optimization design, from factory test verification to on-site temperature rise validation, every stage affects the total cost throughout a 20-year operating period.
Zisheng Electric designs and manufactures transformers according to the IEC 60076 series of standards while making targeted adjustments based on the actual environmental conditions and operating requirements of each project location.
Our product portfolio includes:
For EPC contractors and project owners, transformer selection is not simply an equipment procurement decision. It is a forward-looking decision regarding future 20-year:
Operating costs;
Power supply reliability.
By properly evaluating loss performance, operating environment, and technical solutions during the early project stage, many potential operation and maintenance issues can be avoided in the future.;
Prefabricated substations integrating medium- and low-voltage switchgear.
For EPC contractors and project owners, transformer selection is not simply an equipment procurement decision. It is a forward-looking decision regarding future 20-year:
Operating costs;
Power supply reliability.
