Electricity + Control April 2018

round up

TRANSFORMERS + SUBSTATIONS

Remanufacture of critical components in fast track contract ACTOM Turbo Machines , a division of ACTOM, recently manufactured high preci- sion impellers and pinions for a large 190 kg/h 20 bar pressure integrally-geared mul- ti-stage centrifugal compressor to replace these components after they had been de- stroyed when the compressor failed.

hout, ACTOM Turbo Machines’ managing director, says. “We also had to ensure that the tolerances between the various compo- nents were strictly adhered to, these being especially critical in this instance as the compressor is a four-stage high-speed unit operating at speeds of between just below 20 000 r.p.m. and in excess of 33 000 r.p.m.” Both the first- and second-stage impellers and pinions had to be replaced by newly manufactured units. All the rotating com- ponents, comprising the gear set, impellers and pinions, were balanced in accordance with the international ISO 1940 specifica- tion. The compressor was then assembled and delivered to site where together with the motor, as modified by Marthinusen & Coutts, it was installed by ACTOM Turbo Machines technicians in Air Products’ plant. Further critical procedures carried out by the business unit comprised laser align- ment and fault-finding on all pipe stresses before making ready for commissioning, followed by a rigorous step-by-step start- up procedure.

The work performed on the motor con- sisted of a modification to the rotor to re- duce the excessive vibration that the unit experienced when Marthinusen & Coutts assessed it at its main electrical rotating machines repair and refurbishment facility in Cleveland, Johannesburg. Mike Cham- berlain, the division’s operations executive, says: “With ACTOM Turbo Machines and Marthinusen & Coutts attending to all the mechanical and electrical work covered by this contract, the customer has had the benefit of enjoying the complete one-stop solution that we now offer.” One of two locally reverse-engineered and 5-axis machined impellers.

When the Vanderbijlpark plant of Air Products South Africa awarded the re- furbishment contract to Sasolburg-based ACTOM Turbo Machines late last year, it stipulated a period of three months for completion of the project. At the same time the refurbishment of the 2 500 kW 11 kV 2 pole ac induction motor that drives the compressor was assigned to Marthinusen & Coutts, ACTOM Turbo Machines’ sister business unit in Johannesburg. The compressor is used for direct supply of nitrogen by pipeline to two of Air Prod- ucts Vanderbijlpark’s largest customers in the Vaal Triangle. “Three months is an ex- tremely tight timeframe as it is about a third of the time that would normally be allocated for such a complex task”, Chris Bezuiden-

Enquiries: Richard Botton. Tel. +27 (0) 11 607 1700 or email richardb@mandc.co.za

Dry-type transformers fast-tracked for Bisie in DRC

Project scope also includes two 100 kVA, 400 V/ 400 V Dyn11 dry- type lighting transformers for application outdoors. “The design of these dry-type transformers makes them suita- ble for the climatic conditions at the mine,” says Claassen. “They require only a minimal movement of air across the windings to cool them down, although forced air options can also be employed where necessary if ambient temperatures rise high enough.” The higher efficiency of the cast resin design means that heat losses are lower, along with cooling requirements. This efficiency also reduces the energy consumed by these transformers, and hence will reduce diesel consumption in this application. “An important advantage in this remote location is that dry- type transformers are almost maintenance-free and could last for 25 years without significant attention,” he says. “Oil-filled trans- formers require regular maintenance including oil sample analysis to ensure operational consistency and safety.” With no oil required as a coolant, the dry-type transformer is simple, safe and installable indoors without the need for its own civils infrastructure such as bund walls and structures to ensure safety and environmental protection. “ Trafo Power Solutions works with customers to engineer technically appropriate and proven solutions for their applications,” says Claassen. “The fact that we can design and manufacture with- in this project’s tight deadline is further evidence of our flexibility and ability to meet demanding schedules.” Enquiries:Tel. +27 (0) 11 325 4007 or email david@trafo.co.za

Alphamin Resources’ remote Bisie tin mine is being supplied with fit-for-purpose dry-type transformers by Johannesburg-based Trafo Power Solutions, in a fast track project that will see the complete solution manufactured in just 12 weeks. Bisie’s location – some 160 km north-east of Goma in the Demo- cratic Republic of Congo’s North Kivu province – places constraints on the transformers’ installation that have been taken into account in their careful selection and design. “With a very difficult access road to the mining operation, the substation and transformers have been custom designed to withstand the many stresses expected during transport,” says Tr- afo Power Solutions managing director David Claassen. “To deal with the extreme heat and humidity of over 90%, we have also designed the ventilation and airflow in-house.” The delivery will involve the movement of two 3 000 kVA,

400 V/ 11 kV cast resin transformers housed in six metre high cube contain- ers.The consignment will also include the ventilation systems, lighting and small power equipment. These transformers will be used for stepping up the supply from a diesel powered generator plant – from 400 V to 11 kV – to feed the mine.

David Claassen, managing director of Trafo Power Solutions.

38 Electricity + Control

APRIL 2018