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 has a multilayer structure with copper (or aluminum) wire and strip and layer insulation. The high voltage winding has also continuous disc structure with copper (or aluminum) strip. Windings are impregnated under vacuum condition. Transient analysis has been performed to verify the electrical stress distribution through the windings confirming highest strength in our design.
   
3. The low voltage winding are made of conductor foil (copper or aluminum) and insulating foil. The axial cooling dusts are set to provide more efficient heat dissipating.

• The winding process is to wind inner winding first , and then wind the outer winding on the ready inner winding directly. Both inner and outer winding are conducted VPI (vacuum pressure impregnation) process, the winding will become a compact and ro-bust winding to withstand sudden short circuit force.
  
  
• 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/NEMA there is no de-rating
• Low working temperatures down to -25
• Possibility to include any kind of accessories
• Insulation class H
  

Technology

1. Copper foil and wire, Aluminum foil and wire in high voltage winding
2. Copper and aluminum foil in low voltage winding
3. HV and LV winding winded as a compact and robust block
4. Impregnation under vacuum and pressure condition
5. Low partial discharge values <10 pC
6. Low induction level and step lap configuration granting lower noise level
7. High impulse voltage withstand
8. High short circuit withstand (radial and axial)

Design options

• Reduced loss transformers
• Copper windings
• Low voltage transformers
• Reduced temperature rise
• Multiple primary voltage
• Multiple secondary windings
• Multi winding transformers
• Different location of high and low voltage connection terminals: top and bottom, both on the same side
• Special connection groups
• Autotransformer
• Variable speed drives ( VSD ), rectifiers and excitation transformers for 6, 12, 18 and 24, 30, 36, 48, 54, 60 pulses

Accessories

• Temperature monitor
• Antivibration pads
• Space heaters
• Electrostatic screen ( copper )
• Current transformers on primary and secondary windings
• Plug in bushings
• High voltage earthing switch
• Surge arrestors ( for high and low voltage )
• Flexible terminals
• Connection box
• Bidirectional wheels
• Different enclosures with cable or bus-duct connection
• Earthing bullets
• Lifting and pulling lugs
• Voltage detectors
• Special packings
• Hydrocoolers
• Cable boxes
• Skids