[ Application · Transformer Insulation ]
Transformer Insulation Materials
Materials for oil-immersed and dry-type transformer winding, barrier and structural insulation.
Transformer insulation splits into two problems that are usually solved with different materials: the dielectric barrier between windings and earth, and the mechanical structure that holds the winding geometry stable for thirty years of thermal cycling.
For oil-immersed units, pressboard does most of the structural work while paper and film handle turn and layer insulation. For dry-type units, the thermal class rises and the material set shifts toward aramid papers, laminates and resin systems that survive without oil as a coolant.
Most small and mid-size transformer builders we work with buy across four or five of these categories at once. That is the case where consolidating into a single shipment makes a visible difference to landed cost, and it is worth telling us the whole list rather than enquiring category by category.
[ Material list ]
What goes where
Materials by position in the build. Thicknesses and grades depend on your design — tell us the machine and we will help narrow it down.
| Part / position | Material | Category |
|---|---|---|
| Winding turn and layer insulation | Insulation paper — DMD, NMN, NHN or kraft depending on class and medium | Insulation Paper |
| Main barrier between HV and LV | Pressboard barrier, plain or precompressed | Pressboard |
| Winding spacers and end blocks | Precompressed pressboard, cut to drawing | Pressboard |
| Angle rings and caps | Formed pressboard components | Pressboard |
| Terminal boards and phase barriers | Epoxy glass laminate sheet | Laminates |
| Lead wire protection | Coated fiberglass sleeving matched to class | Sleeving |
| Coil wrapping and banding | Polyester film tape, glass cloth tape | Insulation Tape |
| Winding impregnation (dry-type) | Impregnating varnish or VPI resin | Varnish & Resin |
[ Worth knowing ]
Before you send the enquiry
Oil-immersed and dry-type need different conversations
The material sets diverge sharply. Telling us which you build — and the voltage class — removes most of the back-and-forth from a first quote.
Send drawings for cut parts
Pressboard components are almost always cut to drawing rather than bought as sheet. A drawing gets a firm price faster than a dimension list.
Consolidation matters more here than elsewhere
A transformer build pulls from four or five categories. Quoting them together lets us look at the container as a whole rather than optimising each line separately.
A kit for this application is in preparation
We are putting together a bill of materials for this build type so a first order can be one conversation. Until that page is up, ask us for the material list and we will put it together for your specification.
Materials for this application
[ Questions ]
Buying insulation for transformer insulation
Can you supply pressboard cut to our drawings rather than as sheet?
Yes — cut parts are the normal order form for pressboard. Send the drawing with tolerances and we will quote the parts. For small components in quantity, cutting here usually costs less than shipping sheet and cutting locally.
Do you supply materials for dry-type as well as oil-immersed transformers?
Yes, though the material sets differ. Dry-type builds shift toward aramid paper, epoxy glass laminate and resin systems rated for the higher thermal class. Tell us which type and voltage class you build and we will quote to that.
Can we order several categories in one shipment?
Yes, and for transformer builds it is usually the sensible route. Mixed containers across paper, pressboard, laminate and tape are standard for us rather than an exception.
What lead time should we plan for?
It depends on whether the items are stock grades or made to your width and cut. We would rather give you an accurate date against your actual list than quote a general figure here — send the list and we will confirm.
Tell us what you need to buy
Send the grades, thicknesses and quantities — or just describe the machine you build. We reply within one working day, and we will tell you plainly if something is outside what we can supply well.