Insulation Papers 

With over 10 kV/mm breakdown voltage, insulation paper isolates:

• Between coil layer and between winding
• Winding with core and supporting frame
  

Material used for winding insulation among others:

• Kraft paper
• Diamond-dotted presspaper
• Pressboard
• Crêpe paper

Winding
Made of enameled copper wire, paper-covered rectangular wire and copper or aluminum foil wire with over 98% purity.
Winding is designed to withstand axial and radial force caused by short circuit faults.

Shown at pictures are Automated LV & Simultaneous HV Winding Machines capable of winding three coils at the same time which result in uniform and precise coil properties, both mechanical and electrical properties.

Core
Grain-oriented silicon steel makes the core has low hysteresis and high magnetic permeability to enhance transformer efficiency and reduce overall dimension.

Two methods to build core lamination for precision cutting and minimize losses:

•      Laminating process
•      Wound Process

Picture in the left is automated core cutting and laminating.
Lamination Core
Step-lap joint method produces better flux magnetic compared to conventional method.
It helps reduce iron losses, lower excitation current, audible sound level and prevent lamination shifting under transportation and faults condition.

Wound Core
Smaller losses and lower excitation current also achievable by reducing the number of core joint
Shown at picture, Automated wound core making.

Tank and supporting Frame
Tank and Winding Supporting Frame are made of hot-rolled steel, designed to absorb vibration during operation and able to withstand forces caused by faults without permanent deformation.
Shown at picture, supporting frame and clamp made of hot-rolled steel

 Radiator
Made of cold-rolled steel in form of corrugated or panel type. Designed to dissipate heat from transformer windings by natural or forced cooling without exceeds temperature-rise specifications.
Shown picture, a welder attaching corrugated radiator to a base plate

Painting
Tank and radiators are treated to prevent abrasive corrosion by intensive cleaning, sand-blasting and minimum 70-micron painting. Epoxy paint and hot-dip galvanizing are optional for higher degree of corrosion protection.

 Shown below is transformer prepared into shotblasting machine.

Vacuum Oven
Inner sections are oven-treated followed by vacuum process to enhance dielectric strength, drastically reducing humidity, water content and removing dirt trapped inside inner structure.

Oil Purifying
To enhance insulation performance, transformer oil is purified until over 50 kV/2.5 mm breakdown voltage prior to inner immersion in the tank.

Vacuum oil Filling
Oil filling performed through vacuum chamber to prevent outside contaminants (gas, fume, solids) intrusion.

Finishing and Packaging.

Installing requested accessories and final inspection are done prior to packing and transporting transformer to customers.