As part of a recent UK investment program, Sulzer has built and equipped a dedicated in house test and development laboratory for high voltage coils. Other aspects of the program include upgrading key items of manufacturing equipment at the company’s Birmingham based Centre of Excellence for coil design, manufacture and supply.
These latest developments aim to enable the company to offer both a wider range of coils and shorter lead times for products that require extended insulation system tests.
Manufacturing high voltage (HV) coils is a precise science, and there are many differences between insulation systems that must be accommodated depending on the application. Hydro-electric generators for example are especially challenging to refurbish and require high specification coils that are guaranteed to deliver an extended service life. In contrast, smaller high voltage motors usually require a faster turn around and a cost effective solution to justify repair over replacement.
Sulzer’s investment is guided by its policy of providing the highest quality service, globally. One which the company believes should encompass superior quality repairs, the ability to service challenging applications, provide long service life and deliver fast turn-arounds.
Precision and speed
The key to performance and reliability of copper coils within HV equipment is the insulation system that is built up using specialised tapes and resin, which in the case of Sulzer is made to its own specification. The finished insulation system gives long life and high resistance against electrical stresses and provides good moisture and chemical ingress protection. The exact design and construction of the insulation depends on the machine it is being built for and the environment it will operate within.
The investment program by Sulzer 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.
Sulzer has always had a reputation for delivering high quality resin rich coils with very short lead times. That capability also extends to vacuum pressure impregnation (VPI) coils that can be designed and manufactured before shipping to the customer for the impregnation process. The insulation systems on these can be matched to the customer’s resin specification.
Chris Powles, Head of Electro Mechanical Services, EMEA, stated: “We have a wide customer base that is truly global and includes original equipment manufacturers (OEMs), rewind shops as well as projects that Sulzer delivers directly to end users and service operators. Our ability to respond quickly and deliver a wide variety of coils means that we are often called in to help with unplanned maintenance tasks.”
Development and testing
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 installation of a new 100kV transformer will enable coils to be tested to destruction if necessary. Sulzer coils already withstand 60kV testing, which is 4.5 times running voltage, but in some cases the point at which the insulation system does eventually breakdown needs to be established. This new facility will make it possible to conduct these tests in house and give the necessary reassurance to customers. This new capability eliminates any waiting to fit in with third party schedules, which might have delayed testing in the past.
The laboratory is fitted with modern condition monitoring equipment that continuously analyses partial discharge levels, and locations, within the coils during the tests. This information, complemented by finite element design simulations, allows Sulzer to fully understand the ageing process and produce market leading products.
The investment will enable Sulzer to verify new specifications using actual test data rather than just checking against a supplier data sheet information and trusting it to be sufficient. Based on this, a wider range of coils that match the expectations of customers and the needs of individual applications can be developed.
Cutting edge design
The test lab will complement the upgraded coil design office in Birmingham, UK, which offers 3D computer aided design (CAD), along with other design offices within the Sulzer network. Together with the faster online ordering system, new coil designs and insulation systems can be developed and proven in house to reduce lead times and improve the speed of delivery for a maintenance project.
For those that already have a design available or require a repeat order, the online system is designed to optimise the ordering process and help with planned maintenance programs.
Powles added: “HV coils are used in a wide variety of applications and it is important to be able to tailor their design to the operation. Our ability to speed this process up, in conjunction with our 24-hour manufacturing capability, means Sulzer will continue to lead the way in the rapid repair of large rotating electrical equipment.”