Reyrolle holmes haysmer (HH) switchgear

Project overview

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Introduction

Tenet provided the Front End Engineering Design (FEED) Services as part of a £30M upgrade of a Brewery complex in Ethiopia.

Tenet completed the outline design for an additional 33kV – 7MVA substation that provided resilience in lieu of failure of the existing 3MVA supply. Supplies entered the facility from opposite directions and had disparate origins to increase facility resilience.

Services Provided

Provision of a cost estimate (± 30% uncertainty band) for the supply and installation works associated with the following systems:

  • In-country assessment with both customer and ultimate client liaison;
  • Brewery Complex Substation Design;
  • Modification to Distribution Equipment at Generators Site;
  • 20km long HV Transmission Systems including Earth Nesting, etc.;
  • Transformer Specification and Vendor Liaison;
  • Addition of Metering Equipment;
  • Transformer Primary Side Metering;
  • Transformer Secondary Side Distribution;
  • Lighting, Small Power and Fire Detection.

Development of a scheme design for interfacing to the Ethiopian National Grid.

Challenges

Required by the client on a ‘Fast Track’ basis, Tenet mobilised, undertook an on-site survey and meeting, prepared specifications, approached appropriate vendors and compiled a cost estimate all within a 6 week period.

Technically, there were a number of novel challenges:

  • Transmission and distribution voltage differences; 15kV High Voltage ring-main versus the more usual 11kV;
  • Ethiopian installation standards incongruent to those adopted in the UK;
  • 2500m altitude resulting in equipment specification derating;
  • No available local skilled labour specialised in design or installation of HV work;
  • No in-country supply chain for procurement of HV equipment.

Delivery

Pre-planning. All associated works, including travel, were fully assessed by undertaking appropriate Risk Assessments prior to any works commencing and thus ensuring all relevant inoculations, insurances and permissions were in place.

The works entailed meeting with our Customer and ultimate Client in Ireland and Ethiopia respectively. A walk-down of the existing installation for Condition Assessment was conducted and installation quality reviewed to accurately assess and define the Scope of Works to be undertaken by local labour.
The works entailed meeting with our Customer and ultimate Client in Ireland and Ethiopia respectively. A walk-down of the existing installation for Condition Assessment was conducted and installation quality reviewed to accurately assess and define the Scope of Works to be undertaken by local labour.

The meeting in Ethiopia additionally involved liaison with:

  • Governmental Representatives (Ethiopian Ministry of Energy);
  • Representatives of the Generating Company;
  • Supplier Representatives;
  • Local Contractors.

As a result of the various meetings and review of locally available workmanship the following deviations to local standard working methods were adopted and presented as Technical Innovation;

  • Standard Ethiopian practice is for the use of non-machined and untreated wooden poles for HV distribution; this was rejected in favour of concrete equivalent to provide longevity and long term maintenance cost savings; ]Due to the lack of local skilled labour, prefabricated skids were specified to remove the requirement for on-site fabrication, testing and commissioning;
  • To assure consistent interpretation of the specification and QA compliance, transformer supply was procured from Europe and not local market thereby reducing potential for on-site rejection / failure of this critical path item.

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Conclusion

The FEED study was successful and in conjunction with Tenet, the estimate for detailed design and on-site / commissioning support for the system was accepted by the board of the ultimate Client.

The key aspects of this case study were:

  • Tenet responded to demanding timescales to provide in-country assessments for a novel scope of works and delivered solutions to resolve resilience and capacity issues;
  • By engaging appropriate personnel (from outside our core nuclear capability), Tenet provided a diverse skills portfolio to meet the challenges presented;
  • Tenet successfully compiled a detailed understanding of the client’s requirements against the geographic limitations and operational constraints;
  • This comprehensive operational understanding presented an opportunity to form innovative solutions to upgrade the existing installation and provide long term cost savings;
  • By engaging with Tenet, the client was provided with a specification which utilised, in so far as was possible, standard ‘Commercial Off The Shelf’ systems and components, and specifying either remote or in-situ assembly as best suited to the specific system.

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