Varelen's dry type transformer winding, Their design flexibility includes transformers capable of operating in extremely low ambient temperatures down to -60ºC, providing stronger resistance against short-circuit stress and superior performance under load changes. The linear distribution of BIL ensures the highest possible security against cracks on coils, with no silicone used during coil manufacturing. Varelen's transformers exhibit better performance under dynamic loads and severe ambient conditions (exceeding E2), making them highly suitable for extremely cold environments. Additionally, the vacuum circuit breaker is proven to enhance reliability and safety.
dry type transformer have high voltage winding and low voltage winding
The high-voltage winding is the heart of the cast resin transformer. varelen‘s wealth of expertise
is incorporated in the double layer winding. Our cast resin transformers stand out because the wires of the high-voltage winding are completely embedded in a closed cast resin body with a smooth surface. 
The low-voltage winding of Varelen cast resin transformers is almost always designed as a foil
winding. The benefits of this form of winding speak for themselves:
• High current-carrying capacity
• Balanced temperature distribution in the winding
• High short-circuit resistance
There are exceptions for technical reasons, e.g. for lower power ratings below 160 kVA and for highersystem voltages (Um >7.2 kV),
Encapsulation: Wires are completely embedded in closed cast resin with a smooth outer surface.
Void-Free Construction: Minimizes the risk of partial discharge and enhances insulation life.
Mechanical Strength: The solid casting provides excellent resistance to vibrations and short circuits.
Moisture Resistance: Closed resin body eliminates water ingress, ideal for humid or corrosive environments.
Uniform Current Distribution: The wide surface of foil conductors reduces eddy current losses.
Excellent Heat Dissipation: Balanced temperature rise across the coil enhances lifespan.
High Short-Circuit Strength: Solid foil layers supported with resin bonding provide rigidity against mechanical stress.
Varelen offers a cast resin transformers production with copper and aluminium windings and the option of embedding with a Class F or Class H (180°C) system.
25MVA dry type transformer winding at -60℃( classes C5 E4 F1)
Cast resin transformers are rated in different climatic and environmental classes. The required classes must be determined by the plant operator. Configurations up to class C2 and E2 according to IEC are possible as standard, higher classes must be requested.
CLIMATE CLASSES
The climate class takes into account the lowest ambient temperature during transport, storage, and operation.
ENVIRONMENTAL CLASSES
Air humidity, dripping water, condensation, and contamination are among the environmental
influences for dry-type transformers. These influences are important not only during operation, but also during storage before the transformer is installed. With regard to these different environmental conditions, five environmental classes are defined according to IEC 60076-11 for transformers without special external protective measures.
Class E1:
Occasional condensation may occur on the transformer (for example when the transformer is
switched off). Contamination to a limited extent is possible.
Class E2:
Frequent condensation or light contamination or a combination of both.
Class E3:
Frequent condensation or medium contamination or combination of both.
Class E4:
Frequent condensation or light contamination or a combination of both.
Cast resin transformer windings are widely deployed across various industries and infrastructures due to their safety, low maintenance, and environmental compatibility:
Data centers and hospitals
Substations in urban areas
Renewable energy plants
Railways and airports
Additionally, Varelen's robust HV and LV windings ensure uninterrupted operation even under overload or polluted ambient conditions.
TRANSPORT
As a manufacturer, Varelen understands the relevance of what logistics represents to the customers.
Several decades of experience of the Varelen Logistics Team concerning transport ensure that the transformers are delivered, unloaded and installed on schedule.
With the help of customized logistics solutions, we manage every challenge, be it special dimensions, heavy weights, hazardous substances or extreme local conditions: byroad or inland waterways, down to shipment by ocean vessel, including the subsequent follow-up to our customers world-wide.
Varelen takes care of all official documentation, depending on the final destination and delivery terms.
Different packaging for special applications or conditions
Varelen has a long experience in arranging special transport, as and when it is required.
At Varelen we use our vast experience and expertise to work with our customers to develop specialist solutions, designed specifically to suit their requirements. We produce cast resin transformers winding up to a power rating of 25MVA at a system voltage of 52kV for a wide variety of applications, across a multitude of sectors.
