Trapezoidal Wedge

The trapezoidal wedge or single edge wedge reaches far into the slot tooth, but has the advantage of fitting well in the slot, even when tolerances not achieved. It is the most typical wedge design (angle 60° or 70°) yet and when milling out of plates the most cost saving design.

Double edge wedge

Is less extending into the slot tooth, but more difficult and expensive to mill out of plates. If tolerances are not achieved they are not fitting well in the slot and must be discarded maybe.


Semicircular wedge

A wedge without sharp edges has electrical advantages and therefore this section shape was used in the past sometimes, but the milling process is complex and costly, and it was nearly impossible not to obtain a small edge.

Double edge wedge with flattened edge

This wedge is less weakening the slot tooth and not having a sharp edge has electrical advantages.

Trapezoidal wedge with a straight section

For some applications this shape is preferred, but difficult to mill out of plates, when the straight section is very small.

Trapezoid shape with rounded edges

The perfect shape if a trapezoid design will not be abandoned.

Unsymmetrical double edge wedge

Very similar to the design above but with no round section.

Pedestal shaped wedge, Wedge with basement(s)

It is possible to add a pedestal to any cross-section shape. This type allows to insert as many magnetic material into the slot as possible and therefore to improve electrical properties even more. Another advantage is, that lateral buckling of the slot wedge is less likely because the pedestal is prohibiting this movement. Therefore this shape improves the safety further.

Wedge with basement(s)

The pedestal on the ground fills the space between wedge and coil, where often spacers are used, which are no longer required, so that working time for pro- ducing and inserting spacers is saved and moreover the electric properties are increased because much more magnetic material is present. The pedestal on the top fills the place to the air gap.


SPInduwedge can be manufactured in a great variety of shapes without thinking of additional production costs, because they are pressed and moreover some designs are even not possible with conventional milling process. See table on left side for possible cross-sections and feel free to contact ASPIN to talk about pros and cons of new designs. Some considerations about slot section are not up to date anymore and therefore innovative designs should be considered to improve electrical properties and safety.