classic | mobile
 

Search...

 

Africa’s largest rotor pole refurbishment
4th Quarter 2017, Electrical switching & drive systems & components


In the largest repair of this nature in Africa, Marthinusen & Coutts recently refurbished 11 of the full set of 14 rotor poles of Motor Generator Unit Three at Eskom’s Ingula Pumped Storage Scheme on the Drakensberg escarpment. The rotor poles were extensively damaged during a fault condition at the station, and the return to service of the unit was of national importance.

Working closely with stakeholders, an extensive local programme of testing, dismantling, inspection and repair was conducted by Marthinusen & Coutts within extremely tight time-frames to accommodate the criticality of the project. A technical audit confirmed that facilities at the company’s 8000 m² main workshop in Cleveland, Johannesburg, and its 12 000 m² Power Generation division in Benoni, were up to the daunting task. All 14 main rotor poles were then collected from Ingula Pumped Storage Scheme and dispatched to the Benoni works. Each pole weighed 12 tons, with the coil alone weighing in at over two and a half tons.

It was vital that Marthinusen & Coutts determined not just the electrical status of the windings, but the health and physical integrity of each entire rotor pole (body and coil). They were therefore subjected to insulation resistance and inter-turn insulation tests, comprising both impulse and power frequency inter-turn insulation tests. Extensive visual inspections were also conducted. The test results were analysed, resulting in the decision to refurbish 11 of the 14 poles; two coils were accepted as healthy and the station owned a spare universal coil.

To facilitate the grinding procedure necessary to remove the support side brackets from the main rotor poles, a customised heavy duty jig was manufactured. After the severity of the damage was determined, various techniques and repair concepts were tabled and discussed in detail. It was finally agreed that the coils be stripped of their existing inter-turn insulation layers and the coils be reinsulated, heat cured using 2500 A, including pressing at up to 1000 tons, and re-assembled to the main poles. To fast track the process, Marthinusen & Coutts prepared custom parallel operations at the two facilities by separating the dirty and clean processes, with full clean conditions areas for the critical pressing and heat curing processes.

Manufacturing the tools and equipment for the work demanded substantial engineering and sourcing capacity. Among the items to be custom made were various tables and jigs to help move the coils in and out of the burn-out oven. A coil removal rig to remove coils safely from the main pole body was built, as well as two heavy duty consolidation rigs with a set of 1000 ton hydraulic jacks and their dedicated power control unit. Marthinusen & Coutts also designed and constructed a dimensionally accurate dummy pole centre to help ensure correct fitment of coils to the main poles. Other items included a 2500 A direct current controlled rectifier to assist with the curing cycle, heavy duty turning rigs, lifting assemblies and a magnetic link for inter-turn insulation testing.

The scope of work included pyrolising the coil insulation in a controlled oven environment at 300°C and removing the existing insulation. The copper stacks were cleaned and polished, new insulation was pressed and prepared, and all new insulation kits were manufactured with pre-impregnated Aramid paper. All pole coils were reinsulated and thermo-electrically cured with a 1000 ton consolidation pressure, after which they were cleaned and tested.

Work on the main pole bodies included removing the existing insulation and checking and testing the copper damper winding and series connectors. Weld scars were cleaned and polished and new insulation kits were supplied and fitted. In the final assembly and test stage, Marthinusen & Coutts repaired the existing support brackets to as-new OEM specification and tested them to meet international standards. Coils were fitted to the rotor poles and the coils sealed onto the main poles. Finally the finished rotor poles with coils were tested, crated and transported back to Ingula by Marthinusen & Coutts. Unit 3 is now operating to full capacity. The entire project was carried out under extreme pressure, in record time, and according to all the OEM specifications and requirements for new rotor poles.

For more information contact Richard Botton, Marthinusen & Coutts, +27 (0)11 607 1700, richardb@mandc.co.za, www.mandc.co.za


Share via email     Print this page  

Further reading:

  • Kinetic sculpture interacts with water and light
    4th Quarter 2017, Beckhoff Automation, This Week's Editor's Pick, Electrical switching & drive systems & components
    A fascinating play of water, light and motion.
  • How drives help in papermaking
    4th Quarter 2017, Nidec Industrial Automation Southern Africa, Electrical switching & drive systems & components
    Papermaking machinery, from tissue winders through to suction rolls, embossers, print units and conveyors, must utilise the latest drive technologies to meet modern paper mill production schedules and ...
  • Precious cases
    4th Quarter 2017, Siemens Digital Factory & Process Ind. & Drives, This Week's Editor's Pick, Electrical switching & drive systems & components
    Manufacture of luxury packaging with servo and control technology from Siemens.
  • Advanced software solution for drives
    4th Quarter 2017, Parker Hannifin (Africa), Electrical switching & drive systems & components
    Parker Hannifin now offers an advanced software solution for its AC10 range of compact variable speed drives (VSDs) for industrial motor control applications. It has comprehensive yet user-friendly programming ...
  • New PMAC programmable multi-axis controller
    4th Quarter 2017, Omron Electronics, Electrical switching & drive systems & components
    Omron has announced the global release of its new CK3E programmable multi-axis controllers and industrial PC platform NY51-A IPC programmable multi-axis controllers (PMAC). The company worked together ...
  • Drive solutions for anaesthesia
    4th Quarter 2017, Horne Technologies, This Week's Editor's Pick, Electrical switching & drive systems & components
    There are many experiences we would happily do without. Operations under general anaesthetic are definitely one of them. Anaesthesia and ventilation systems are a critical part, and perfectly tuned drive ...
  • Keep it clean with Sun filter cartridges
    4th Quarter 2017, Axiom Hydraulics, Electrical switching & drive systems & components
    When a valve fails to work properly, so will your machine. The leading cause of hydraulic valve failures is contamination – an easy thing to prevent. However, in compact systems where space is at a premium, ...
  • Yogurt packaging made 30% faster
    4th Quarter 2017, Omron Electronics, Electrical switching & drive systems & components
    French packaging machine manufacturer, Packinov asked its local Omron service department to collaborate on developing a new machine with high levels of compactness and cost efficiency. Packinov not only ...
  • Brewing up a taste sensation
    4th Quarter 2017, Siemens Digital Factory & Process Ind. & Drives, This Week's Editor's Pick, Electrical switching & drive systems & components
    Siemens logic module optimises beer brewing process.
  • Drive system for food and beverage
    4th Quarter 2017, SEW-Eurodrive, Electrical switching & drive systems & components
    Movigear drive systems are particularly suited for the food and beverage industry, with its dual demands of high hygiene levels and energy saving, combined with the need to limit any downtime. SEW-Eurodrive ...
  • Power quality and motor analyser
    4th Quarter 2017, Comtest, Electrical switching & drive systems & components
    Fluke has introduced the new Fluke 438-II power quality and motor analyser, adding key mechanical measurement capabilities for electric motors to the advanced power quality analysis functions of the Fluke ...
  • IE3-compliant motors for wastewater treatment plant
    4th Quarter 2017, SEW-Eurodrive, Electrical switching & drive systems & components
    A major upgrade to a wastewater treatment plant in the Eastern Cape is taking advantage of the energy-saving and cost-efficiency features of the latest IE3-compliant DRN motors from SEW-Eurodrive. An ...

 
 
         
Contact:
Technews Publishing (Pty) Ltd
1st Floor, Stabilitas House
265 Kent Ave, Randburg, 2194
South Africa
Publications by Technews
Dataweek Electronics & Communications Technology
Electronic Buyers Guide (EBG)

Hi-Tech Security Solutions
Hi-Tech Security Business Directory

Motion Control in Southern Africa
Motion Control Buyers’ Guide (MCBG)

South African Instrumentation & Control
South African Instrumentation & Control Buyers’ Guide (IBG)
Other
Terms & conditions of use, including privacy policy
PAIA Manual





 

         
    classic | mobile

Copyright © Technews Publishing (Pty) Ltd. All rights reserved.