1. The magnetic core has a miter step joint to ensure optimum performance and minimum sound levels by using step lap technology. The magnetic steel is cut to length sequentially and automatically stacked. This ensure dimensional accuracy and single sheet interlacing within the full stack.
   
2. The high voltage winding commonly has foil disc or round wire (aluminum or copper). Windings are cast under vacuum with epoxy resin. Transient analysis tests have been performed to verify the electrical stress distribution through the windings confirming the highest strength in our design.
   
3. The low voltage windings are made of conductor foil, alternatively round or rectangular wire, when needed, (aluminum or copper) and insulating foil pre-impregnated with epoxy resin. After the winding process, the coil is cured into an oven resulting in an extremely compact winding, which can withstand the dynamic stresses produced by a short-circuit.

• The encapsulation process is a key stage within the manufacturing process. Encapsulation is carried out under the most rigorous conditions in order to ensure optimum insulating and mechanical characteristics. The resin mix is prepared in a continuously monitored mixing plant where all the components are mixed together just before the encapsulation process.
  
• Inside the vacuum casting chamber, the resin is introduced into the mold. The components are mixed together which ensures that the viscosity of the resin when poured in the molds is very low, filling interstices, and allowing the finished winding to reach the lowest level of partial discharge. Once the casting is finished, the coils are placed into the curing oven for the resin gel to cure and acquire the optimal final electrical and mechanical properties.
  
• In Putuo Electric factories, the whole tendering, design, and production process is controlled and planned with sophisticated software. This ensures the highest productivity and reduced production time while maintaining the highest quality standards.

Design

• Guarantee of accurate temperature rise in windings; in case of enclosure IP/20/21/23/30/31/40/41, there is no de-rating
• Low working temperatures down to -40°C
• Possibility to include any kind of accessories such as rollers, fans, temperature controllers and etc.
• Insulation class F, H (optional)
• C3, E3, F1 certification (optional)
  

Technology

1. Aluminum, copper foil disk, or other materials in high voltage winding
2. Aluminum, copper foil, or other materials full width in low voltage winding
3. Casting under vacuum
4. Low partial discharge values <10 pc
5. Smooth surface
6. Self-extinguishing
7. Dust resistance due to sealed coils (optional)
8. Silicon free (optional)
9. Low induction level and step lap configuration, granting lower noise level
10. High impulse voltage withstand
11. High short circuit withstand (radial and axial)
12. Reduced footprint

Design options

• Reduced loss transformers
• Copper/ Aluminum windings
• Low voltage transformers
• Class H transformers
• Reduced temperature rise
• Multiple primary voltage
• Multiple secondary windings
• Multi winding transformers (2, 3, 4, or 5 on the same core)
• Encapsulated low voltage windings
• Sealed or casted low voltage winding
• Impregnated high voltage windings
• Different location of high and low voltage connection terminals: top and bottom, both on the same side
• Special connection groups
• Variable speed drives (VSD), rectifiers, and excitation transformers for 6, 12, 18, and 24 pulses
• Different coupling factors from 0.15 up to 0.9
• Earthing transformers
• Seismic and vibration reinforcement system
• Outdoor operation
• Offshore applications
• Reduced footprint

Accessories

• Enclosure IP20/21/2/23/30/31/40/41 (optional
• Temperature monitor)
• Antivibration pads
• Space heaters
• Electrostatic screen
• Current transformers on primary and secondary windings
• Plug in bushings
• High voltage earthing switch
• Surge arrestors (for high and low voltage)
• Cooling fans with up to 40% power increase
• On load tap-changers (OLTC)
• Flexible terminals
• Connection box
• Bidirectional wheels
• Different IP/NEMA enclosures with cable or bus-duct connection
• Earthing bullets
• Lifting and pulling lugs
• Voltage detectors
• Voltage automatic regulator (VAR)
• Special packings
• Hydrocoolers
• Cable boxes Containerized solutions