Electricity + Control February 2019

round up

TRANSFORMERS + SUBSTATIONS

Fast-track repair of generator rotor

removed before the rotor body could be prepared for the rewind process. Jigs and tooling were specifically manu- factured to ensure symmetry in the winding process. The winding process was execut- ed in LH Marthinusen’s positively pressur- ised clean area conditions in order to avert contaminants in the winding process. Coil interconnections were modified to allow individual access for testing purpos- es. This feature was not built into the origi- nal manufactured design. To provide mechanical stability to the overhang windings, both ends were over- layed with resin impregnated thermoset- ting unidirectional glass fibre tapes. The completed rotor finally undertook a heating cycle for the thermosetting resins to cure. The rotor balancing was outsourced to one of the largest facilities in the Southern Hemisphere. The balancing was success- fully concluded in a four hour period which included the specified overspeed run of

ACTOM division LH Marthinusen (LHM) – a leading repairer of transformers and large rotating machines, and manufacturer of specialised transformers – recently fast tracked a breakdown repair of a 60 MW sa- lient pole generator rotor. The generator rotor is used in a cogen- eration configuration by an Independent Power Producer (IPP) with renewable ba- gasse as its energy source. The out-of-service rotor had major fi- nancial implications for the IPP, as the unit produced a large percentage of the compa- ny’s export energy. A fast-track repair was offered by LH Marthinusen, reducing the normal completion timeline by four weeks. Being over 6 m in length, with a diameter of 1.4 m and a mass of 28 metric tons, the rotor had process equipment challenges. In order to fast-track the unit repair it was necessary that coil manufacture proceeded parallel to the failed windings being removed from the rotor body. All in all, three tons of copper conductors were

120% for two minutes. On completion of site assembly a check balance was executed with the generator load brought up to 80% in a three hour pe- riod. ACTOM (Pty) Ltd is the largest manufac- turer, solution provider, repairer and distribu- tor of electro-mechanical equipment inAfrica, offering a winning and balanced combination of manufacturing, service, repairs, mainte- nance, projects and distribution through its 40 outlets throughout Southern Africa. ACTOM is also a major local supplier of electrical equipment, services and balance of plant to renewable energy projects. In addition, it holds numerous technol- ogy, distribution and value added reseller agreements with various partners, both lo- cally and internationally. Enquiries: +27 (0) 11 615 6722 or visit www.lhm.co.za