■ coil manufacture

The provision of high quality coils produced quickly to exact specifications is an essential part of rewinding large machines. Within the UK and Australia, Sulzer Dowding & Mills has some of the most modern dedicated coil manufacturing facilities, for AC & DC motors and generators of all types and sizes.

■ design
Many of the HV machines repaired by Sulzer Dowding & Mills are over 25 years old with original insulation systems which are either obsolete or would now be considered inadequate. Replacement coils for these machines can be designed using modern materials with enhanced temperature classification, increased dielectric strength and improved mechanical stability.

In many cases, an increased copper cross-sectional area can be accommodated, which reduces the copper losses, reduces the stator winding temperature rise and improves efficiency for the operator.

Other site problems, such as humidity, contamination, slot discharge and high operational temperatures are also considered during the redesign process.

Alongside the in-house computer-aided design facility, a comprehensive database contains coil details for thousands of machines from manufacturers world-wide. This enables the checking of existing designs and any improved performance from a redesign. The system also issues production drawings and process instruction sheets, automatically.

■ copper supply
Delays are not incurred waiting for exact size copper as the plant includes a highly sophisticated in-house copper rolling mill and a range of conductor covering machines. These ensure the precise conductor is produced for each coil system.

■ manufacture
A range of looping machines and automatic forming machines gives each coil consistent geometry and size for any configuration of overhang, whilst computer controlled hydraulic coil presses and taping machines combine to ensure insulation integrity and accurate slot fit.

■ testing & inspection
The Industry Standards of BS EN 50209: 1999, and ESI Standard 44-5 are all met through dedicated coil testing before fitting to the machine or dispatch to the site.

■ packaging & transport
To ensure that the care taken in manufacture is not compromised in any way, all packaging and methods of freight have to meet stringent quality controls.