Improving quality of high voltage coil manufacturing

Until now, the Falkirk site has used a 1,250kVA diesel generator that operates through two step-up transformers to provide 3.3 to 11kV via high voltage switchgear to the test cell. This setup ensures a reliable power source for testing that is not affected by local demand on the power grid.

The new investment by Sulzer will add a 2,000 and a 700kVA generator to the site that will be synchronised through a 4,000A low voltage switchboard, as well as a new 2,500kVA transformer, that will double the capacity of the test bed.

The original capacity of the service centre was 1,000kW in load testing, of which 800kW could be used for testing vertically-orientated motors, across a full range of voltages from 400V up to 11kV at both 50 and 60Hz. The installation of the new equipment will increase the load testing capacity to 2,000kW for horizontally-orientated motors as well as an increase in voltage to 13.8kV. 

The majority of the equipment tested in the additional capacity will be large, high voltage, AC motors, but the possibility to test DC motors up to 600V, with a loading up to 800A will still remain.

Furthermore, an additional test-bed area is now in place to allow multiple motors to be tested alongside each other. This means that if the testing of one motor needs to be extended, it will not hold up other projects, allowing equipment to be returned to customers on time.

The new test bed offers customers the possibility of load testing generators using a slave motor to turn the generator and connecting the output to a load bank. In this way, generators that have undergone major repairs can be tested to ensure that they are fit for purpose before they are re-installed and recommissioned.

As part of this upgrade project, the test area is equipped with the latest monitoring controls and safety equipment that provide the test engineers with remote visualisations of the sensor readings while protecting them from large pieces of rotating equipment. A customer viewing area is also available, from where owners of equipment can watch and interact with the test engineers to ensure that the entire process is transparent and straightforward.

Marc Stuart, Service Center Manager, at Sulzer’s Falkirk site, said: “In the past, only equipment that had undergone a major repair would have received a full-load performance test. Now, more and more customers are requesting full-load testing following an overhaul, giving them complete peace of mind that the equipment is fit for purpose.

“Our customers are now able to see their motor operating at load and can review a complete set of test results, including vibration analysis, partial discharge, motor current signal analysis (MCSA) and other condition monitoring data. This is providing our customers with confidence, not only in the performance of the motor but in the service solutions they are receiving. A full test report can then be issued, providing a baseline set of data that they can use once their equipment is installed and running in its application.”

Sulzer’s investment program in the UK has delivered a range of new equipment and machinery including replacement looping machines, shaping machines and a robotic taping machine that will together provide enhanced precision, quality and speed in the manufacture of HV coils.

A major investment has also been made in the design and testing capabilities at Sulzer, with the creation of a ‘Coil Test Lab’ that will enable voltage endurance and thermal cycling tests to be carried out in-house. These tests can determine the durability and expected lifetime of HV coils and ultimately provide a quality rating for the insulation system.

The final step in the repair process for high voltage machines is balancing the rotors to ensure smooth and reliable operation, especially during start-up and shutdown procedures. Sulzer has one of the only independent high-speed balancing facilities in the UK and it has recently been updated with the installation of CABFLEX3 software and additional hardware that will significantly reduce the time required to balance a flexible rotor.