Three-phase diamond coil windings

One of the most important areas of our company is the fabrication of preformed windings with profile wire.

The smaller dimensions of preformed coils are primarily manufactured for traction machines. Maximum dimensions up to a fish length of 5.5 m can be produced.

The individual coils can weigh up to 60 kg and are produced on special coil spreading machines. Pole numbers from 2 to 24 can be realised. There also exist various rated voltages up to 15 kV that, depending on the machine's field of application, may require the realisation of the corresponding insulation thicknesses.

We provide two basic types of insulation:


The resin-rich system, in which the coil leg is wound with resin-rich mica tape and cured in the hot coil press. There are eight presses available for this procedure, with which sleeves up to 7 m in length can be pressed. After this process, the coils are ready to install. They can also be ordered as coil sets or installed by our technicians on site. The advantage of the Resin-Rich-System is that individual coils can be replaced easily.

The special area of application for resin-rich coils is for extreme stator diameters or locations at which only on-site repair is possible. The electrical parameters up to 13.8 kV rated voltage only vary to a minor degree between the resin-rich and VPI methods.


In addition, we offer the so-called VP-system. In this procedure the insulation is applied as dry mica tapes using robots or semiautomatic machines. If necessary, this task can also be performed by hand. These ‘soft’ coils are mounted into slots; the winding is impregnated in the vacuum pressure process after connecting and cured while rolling in drying ovens.

The VPI procedure is up to 20 percent less expensive than the resin-rich process. This cost advantage derives from taping machines used for realising the required insulation thicknesses.

A disadvantage of the VPI process is the fact that an individual defective coil can hardly be removed from the overall installation. In contrast, when applying the resin-rich technique, individual coils can be easily exchanged.

Special fields of application of resin-rich coils are extremely large stator diameters or locations that only allow installations on site. In terms of quality the electrical parameters up to a rated voltage of 13.8 kV do not significantly vary between the resin-rich and the VPI process. However, for voltages of 15 kV and above, the VPI process is usually preferred for epoxy resin impregnations. This is because when using epoxy resin a vacuum of 0.1 mbar can be achieved without the evaporation of solvents. Consequently, significant tanδ values can be reached. The tanδ also serves for the quantitative evaluation of the air content in the insulation system.

Technical parameters

Feasible dimensions of preformed coils in general
  • Stator inside diameter up to 300 mm » Spread angle: 0 to 140°
  • 120 to 1200 mm chord (under 200 mm hand tape)
  • Length of straight core part: 280 to 3500 mm
  • Cross-section of straight core part: 5 x 15 mm to 25 x 70 mm (maximum of 1400 mm²)
  • Feasibility of other dimensions will be checked upon request
Feasible dimensions of preformed coils for traction machines
  • Stator inside diameter up to 280 mm
  • Spread angle: 0 to 160°
  • 120 to 340 mm chord (under 200 mm hand tape)
  • Length of straight core part: 200 to 600 mm
  • Cross-section of straight core part up to 10 x 20 mm
  • Feasibility of other dimensions will be checked upon request
Machinery preformed coils
  • Fish winding machine with drum stands and wire guide
  • Taping machine for the protective tape on fish
  • Coil spreading machine
  • Hydraulic hot coil press for preforming
  • Semiautomatic taping machine for main insulation
  • Winding robot for main insulation and end winding side (non-connection-end)
  • Turning equipment up to 50 t
  • Insertion device for coils exceeding 25 kg
  • Soldering device for cross sections up to 300 mm
  • VPI impregnation system
  • Drying oven
  • Application of the main insulation using coiled tubing (wide strip) or winding robot (tapes) during the resin-rich process
  • Hydraulic hot coil press for main pressing
  • Completion of up to 20 parallel wires
  • Fish length: 300 to 5,500 mm