Why Choose Us
Our Factory
Our factory is able to produce transformers that comply with various international standards such as IEC, IEEE, ANSI, CSA, EN, etc.
Product Application
State Grid, transportation, urban construction, petrochemical industry and other places.
Our Service
24 Hours online service
Mission
Our mission is to put people first, strive for development through technology, compete for the market through quality, and create benefits through brand.
Professional Team
The Yawei team is composed of experts and professional knowledge, helping us quickly solve customer problems.
Global Business
So far, our equipment has been exported to multiple regions such as South America, North America, Asia, Australia, Europe, and Africa.
Related Product
Cast Resin Dry Type Transformer
●Ratings from 100kVA to 10MVA
●Typical 11000/433V or 11000/415V voltage ratio, +/- 2.5 or 5%
●Ecodesign Tier 2 losses
●Aluminium or copper windings
●ANAN or ANAF (fan) cooled
●Supplied standalone (IP00) or with a variety of IP rated enclosures
●Wide range of ancillaries
●18 month warranty
Phase:Three phase
Capacity:0.5KVA-2000KVA
Input voltage:Customize various voltages according to user needs
The output voltage:Customize various voltages according to user needs
Output voltage accuracy:±1%
Voltage change rate:≤1.5%
●Rated Power 16kVA to 3,200kVA, Voltage Class 6kV, 10kV
●Rated Power 16kVA to 3,200kVA, Voltage Class 20kV, 35kV
●High Power Transformer – 4,000kVA to 25,000kVA, Voltage Class 6kV, 10kV
●Power Transformer 25kVA to 63kVA
●Auxiliary Transformer for Power Stations and other facilities
●Power Transformer with Seismic, Vibration and Mechanical Resistance
●Power Transformer with OLTC

A dry type transformer is cooled by normal air ventilation instead of a liquid such as mineral oil or Envirotemp FR3. The early transformers manufactured by Westinghouse and General Electric were air cooled because they operated at low power and voltages. Most instrument transformers and low-voltage power chargers today are also dry types. Liquid cooling inside sealed tanks and metal enclosures became the standard for AC power distribution transformers due to the higher induction heat losses and exposure to all-weather conditions. Because of improvements in design, materials and manufacturing methods over the past three decades, dry type transformers not only compete with liquid-cooled transformers in the medium voltage range (2.5KV – 34.5 KV) but have significant advantages in many commercial and industrial applications.
Key Points In Maintenance For Dry Type Transformers
Maintain a Temperature Log
Periodically read and record the transformer temperature controller at normal load and compare the reading with the log history.. All coils should read approximately the same temperature with a 3 phase load. A large difference or a persistent increase in operating temperature at constant load may indicate a problem with either the air cooling system or the transformer.
Perform Maintenance Only On De-Energized Units
Caution: The transformer must be de-energized (both primary and secondary circuits disconnected) and all terminals grounded before performing any inspection, cleaning, servicing, or testing on the unit. An Arc Flash suit should be worn when de-energizing the transformer, but once it's de-energized, locked out, tagged out and grounded, an Arc Flash suit is not necessary.
Visual Inspection
Caution: This is a visual inspection only. It is not necessary to touch any part of the transformer when performing the inspection.
Cleaning the Unit
Caution: For safety reasons, physical contact with the transformer should be minimized during cleaning even if the unit has been de-energized , locked out and and grounded.
Checking for Potential Problems or Defects
While cleaning the transformer, look for rust on the clamps and core steel, any carbonization or tracking on the windings and insulation.
Examine the windings and surfaces more closely for discoloration which could be a sign of overheating or a loose connection.
Check for cracked, discolored or loose insulators.
Check for loose, pitted, corroded or discolored electrical connections.
If possible, tighten or replace any hardware components; otherwise you should contact a professional to evaluate and repair the transformer.
Fans, motors and other auxiliary devices should be inspected and checked for proper operation.
Report all abnormal or suspicious conditions in writing to the plant engineer or facilities manager, who will determine if any additional testing or service is needed before re-energizing the unit.
Tests During Routine Maintenance
During routine maintenance, several tests of the transformer may be made addition to the inspection and cleaning. Performance of these tests are regulated by NEC 450.11.11. These tests are necessary only if discoloration, carbonization or other evidence of overheating or shorting is found. They will verify the correct operation of the unit and can detect issues that are not apparent from a visual inspection. Failure of any test requires further investigation and service before the unit is put back in service.
Transformer Turns Ratio (TTR)
A TTR assesses the condition of the transformer windings and core. It tests whether the actual voltage ratio between the primary and secondary windings (for each phase and tap point) agrees with the nameplate or certified values. They should agree within 0.5% (NEC 450.11.2 & IEEC57.12.91.)
Insulation Resistance Test (IR)
The IR tests the integrity of the insulation between coil winding conductors. Each transformer rating has a minimum required resistance level measured in Mega- Ohms. Readings below this level indicate a degradation of dielectric strength. This is a warning sign of a potential transformer failure. (NEC 450.11.11.3)
Winding Resistance Test (WR)
The measured resistance of the coil windings for each the voltage taps being used should be within 1% of the factory tested value or the most recent test. (NEC 450/11.11.7)
Other Tests
Other diagnostic tests require special equipment and facilities, and should be performed experienced professional engineers.
What Are The Main Advantages Of a Dry Type Transformer?
Self-Extinguishing, Low Fire Hazard
A dry type transformer comes with an eco-friendly material on its insulation. So, it comfortably winds in a self-extinguishing manner, is flame retardant, and of course easy to maintain. With it, you won't have to invest in a fire extinguisher. Plus, even under the influence of arcing, it doesn't produce toxic gases.
Zero Oil Usage
As mentioned earlier, the dry transformer doesn't need any liquid to cool. It only requires air to remain cool. So, you won't have to incur extra expenses to get oil, or any other liquid, plus the maintenance costs attached to them. It's safe to say that this is an almost maintenance free transformer, so you can stay worry-free.
Eco-friendly and safe
Since dry transformers don't use oil or liquids for that matter, you won't have to deal with oil leaks. Or any other form of environmental pollutants. Plus, they are self-extinguishing meaning they rarely explode. Also, the dry type transformers are widely known to withstand unexpected weather changes, making them suitable for heavily polluted and condensed environments.
Low cost installation and lower load losses
Due to their low risk nature, there are barely any restrictions when installing the dry type transformers. You also won't have to deal with other environmental precautions such as groundwater protection. Also, these transformers can serve you for over 20 years, with low chances of failure.
Low Maintenance
We cannot insist on this enough. The dry type transformers are extremely low maintenance. Like you barely have to even maintain them. As long as they have air to cool, you won't have to deal with built-up dirt. Also, you will never have to deal with liquid testing. However, a routine expert inspection is recommended, and that shouldn't be too hard.
Sustainable
When you use a dry transformer, you are playing a key role in ensuring we save our earthly resources. With it comes low electricity usage, 90% recyclable materials, and a reliable service of 20+ years.
What are the Applications of Dry Type Transformers?
Chemical, oil, and gas industry: Dry-type transformers are used to supply power to various equipment and processes that involve flammable or explosive substances, such as refineries, petrochemical plants, pipelines, offshore platforms, etc.
Environmentally sensitive areas: Dry-type transformers are used to protect the environment from oil spills or leaks that can contaminate water sources, soil, or wildlife habitats, such as water protection areas, forests, wetlands, etc.
Fire-risk areas: Dry-type transformers are used to prevent fire hazards or minimize fire damage in areas that are prone to fire outbreaks or have strict fire regulations, such as indoor substations, underground substations, hospitals, schools, hotels, shopping malls, etc.
Renewable generation: Dry-type transformers are used to connect renewable energy sources to the grid or to the load, such as wind turbines, solar panels, hydroelectric plants, etc.
Other applications: Dry-type transformers are also used in other applications that require high performance, low maintenance, or special features, such as traction systems, marine systems, mining systems, data centers, etc.
What Are The Important Factors To Design a Dry Type Transformer?
The insulation type determines the temperature rating, dielectric strength, mechanical strength, and thermal shock resistance of the transformer. Generally, F and H-class insulation materials are used for dry-type transformers because they can withstand high temperatures (up to 155°C and 180°C, respectively) and have good electrical and mechanical properties. Common insulation materials include varnish, epoxy resin, polyester resin, etc.
The winding material determines the conductivity, resistance, loss, and mechanical strength of the transformer. Generally, copper and aluminum are used as winding materials for dry-type transformers because they have high conductivity and low cost. Copper has better conductivity and mechanical strength than aluminum, but it is more expensive and heavier. For the same current rating, copper requires less cross-section area than aluminum.
The core material determines the magnetic flux density, permeability, hysteresis loss, and eddy current loss of the transformer. The core material should have high permeability and low hysteresis loss to reduce the no-load loss and improve the efficiency of the transformer. Common core materials include silicon steel, cold rolled grain oriented steel (CRGO), amorphous metal, etc.
The regulation of a transformer is the ratio of the voltage drop at full load to the no-load voltage. The regulation indicates the ability of the transformer to maintain a constant output voltage under varying load conditions. The regulation depends on the impedance and resistance of the transformer. A low impedance and resistance result in low regulation and better voltage regulation. The leakage reactance of a dry-type transformer should be kept within 2% during design to achieve low regulation.
The life expectancy of a transformer indicates how long it can operate reliably before degradation, influenced by factors like temperature, moisture, dust, and corrosion. The insulation class and quality of the dry-type transformer should be chosen to withstand high temperatures and harsh environments without degrading. The temperature rise of the transformer should not exceed the limit specified by the insulation class.
The losses of a transformer are the difference between the input power and the output power. The losses consist of no-load losses and load losses. The no-load losses are independent of the load and include core loss and eddy current loss. The load losses are proportional to the load and include copper loss and stray loss. The losses affect the efficiency, heating, and cooling of the transformer. The core material, winding material, insulation material, and design parameters should be selected to minimize the losses and maximize the efficiency of the dry-type transformer.
The overloading of a transformer is the condition when the transformer operates beyond its rated capacity or temperature limit. The overloading causes overheating, insulation breakdown, short circuits, or fire in the transformer. The overloading can be caused by excessive load demand, harmonics, faults, or ambient temperature. The dry-type transformer should be designed with sufficient margin to handle overloads without damaging its components or performance. The dry-type transformer should also be equipped with a fan-cooling system or an air-conditioning system to dissipate the heat generated by overloads.
The K-factor is a measure of the ability of a transformer to withstand the heat generated by non-sinusoidal currents in its windings. Non-sinusoidal currents are caused by various electronic devices that produce harmonics in the voltage and current waveforms. Harmonics increase the losses, heating, and distortion of the transformer. A high K-factor indicates that the transformer can handle higher levels of harmonics without overheating or degrading. The dry-type transformer should be designed with a high K-factor to provide long-lasting life and reliable performance in applications that involve non-sinusoidal currents.
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Our Factory
Through years of international engineering experience, our factory is able to produce transformers that comply with various international standards such as IEC, IEEE, ANSI, CSA, EN, etc. From product development, design, production to manufacturing and testing, the Yawei team strictly controls every process. So far, our equipment has been exported to multiple regions such as South America, North America, Asia, Australia, Europe, and Africa. Since 1992, Yawei Transformer has completed multiple overseas projects. We are confident in winning any project, which will help our potential customers become more competitive in the global market. For Yawei, our mission is to put people first, strive for development through technology, compete for the market through quality, and create benefits through brand. We focus on continuous improvement and strive for the green development of electrical equipment. The Yawei team is composed of experts and professional knowledge, helping us quickly solve customer problems. Whether selecting the current product from our catalog or seeking engineering assistance for your application, please contact our customer service center to discuss your procurement requirements.
FAQ
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