Applications
Insulation Parts and Stampings for Generators
Reliable insulation for high voltages and load cycles, designed individually for the most varied generator types and sizes.
Insulation parts inside a generator
In the stator the slot liner lines the slot. In larger generators the slot is closed with glass fibre slot wedges: rigid laminate profiles that hold the winding securely even against the high forces of a short circuit. In the rotor of large generators, turn insulation separates the stacked copper turns and opens the path for cooling air through slotted holes. For geometries outside the standard we make special parts.
Generators are rarely built in large series. That is exactly why we fit here: samples and small series from a quantity of one, without tooling cost sinking the project.
High voltage changes the insulation system
Generators operate at considerably higher voltages than most electric motors. Large generators run with stator voltages in the kilovolt range. The insulation is therefore stressed not only thermally and mechanically but above all electrically: it has to withstand the field strength permanently and must not be gradually destroyed by partial discharge.
The winding design adds to this. Large generators often use form-wound coils or Roebel bars instead of classic round wire. Roebel bars consist of many transposed strands that reduce current displacement and additional losses in the conductor. Form-wound coils and bars are insulated before insertion and placed in open slots, which are then closed with a slot wedge.
VPI or resin rich
Two insulation concepts have become established for high-voltage windings. In VPI (Vacuum Pressure Impregnation) the conductors are wrapped with porous mica tapes, then the winding is impregnated with resin under vacuum and pressure and cured, often the complete stator at once.
In the resin rich process the tapes are already pre-impregnated with resin. Each bar and coil is cured individually under heat and pressure and only then installed. The chosen concept defines the requirements for all other insulation parts, from resin uptake of the slot liner to the fit of the slot wedges.
Typical insulation materials
The main insulation of high-voltage windings consists of high-voltage products such as mica tapes and prepregs. Mica is particularly resistant to partial discharge and therefore indispensable in the high-voltage range.
Around this main insulation, proven sheet materials are used: NMN, i.e. NPN laminate of Nomex and polyester film, NKN laminate for the highest thermal demands and Nomex 410 aramid paper for class H. Materials with an absorbent surface bond well with the impregnating resin, which anchors the insulation permanently and improves heat dissipation.
Manufacturing at Hauler & Hermann
Our expertise is in folding, forming and bending insulation material so parts sit like a second skin. The tool system developed for this and our own tool shop make us independent of suppliers and fast in implementation.
On request we verify the fit in advance on a 3D printed model of your slot geometry. Production is certified to DIN EN ISO 9001 and DIN EN ISO 14001.
Do you have an application in mind?
Describe your installation situation and we will check feasibility.
Matching Products
Slot Liners for Electric Motor Stators
Slot liners separate the winding from the core and prevent flashovers in the stator slot.
Learn more →
Turn Insulation for Air-Cooled Generator Rotors
Turn insulation separates the copper turns in a generator rotor and guides the cooling air through slots.
Learn more →
Slot Wedges (Top Sticks) from Glass Fibre Laminate
Slot wedges close the stator slot mechanically and hold the winding securely under high forces.
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Custom Parts for Demanding Insulation Systems
For particularly demanding insulation systems we produce custom parts.
Learn more →Matching Processes
More Application Areas
Motor Construction
Custom insulation parts for over 60 years in special machinery, power tools, ventilation, conveyor, rail, aircraft and marine technology.
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Wind Power
Insulation parts for onshore and offshore wind generators, process-reliable even for the largest generators on the market.
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Electronics and Lighting
Flexible insulation with excellent electrical properties, Kapton for fuel cell stacks, batteries and chips.
Learn more →Frequently Asked Questions About Insulation for Generators
Do you produce for generators in small series?
Yes. Samples and prototypes from a quantity of one. Steel rule dies keep single machines and small series economical.
Why glass fibre slot wedges instead of folded slot closures?
In large generators short circuits and vibration put high forces on the winding. A folded slot closure made from sheet insulation is not enough. Glass fibre laminate wedges sit form-fitting in the slot opening and carry the load mechanically.
What is the difference between VPI and resin rich?
With VPI the wound insulation of porous mica tapes is impregnated with resin under vacuum and pressure. With resin rich the tapes are already pre-impregnated, and each bar is cured individually under heat and pressure.
Which materials are used in generators?
Mica tapes and prepregs for the main insulation of high-voltage windings. NMN or NPN, NKN and Nomex for slot liners, interlayers and turn insulation, depending on the thermal class.
Can you produce very large dimensions?
Yes. Large format stampings up to 1,000 x 2,000 mm, and longer profiles through our own folding tool system.