Site ServicesAsset Management for Modern Networks

The core expertise of Fundamentals relates to voltage control for electrical power networks. This comes from a deepunderstanding and practical experience of on-load tap changers, control schemes and the electrical network itself. Building on this expertise, Fundamentals has developed a comprehensive range of services to fully support customers on site for power control:

• Protection and Control Schemes

• Tap Changer Maintenance

• Transformer Upgrade Solutions

Protection and Control SchemesPower transformers and switchgear are critical components in power grid substations. Control schemes relating to these components are equally important and require careful managementto ensure optimum performance of thesystem. Protection, tap changer control andtransformer temperature control (fan andpumps) schemes could cause significantissues if not functioning correctly.

Many control schemes are operational wellbeyond their intended design lifetimes; it is easy to find schemes which were installed more than 40 years ago. Such agedschemes become increasingly difficult tomaintain as components and spare partsbecome obsolete. An added problem is that the network has changed since it wasbuilt to operate as a passive system with‘trickle-down’ power flows. These days,because of increasing levels of distributedgeneration, the network experiences bi-directional power flows which can causeadditional problems with existing controlschemes.

Features

Fundamentals offers upgrade services for tap changer control (voltage control) and protection schemes to ensure optimumperformance for the modern network. With all skills, knowledge and capabilities in-house, this service can operate as aturnkey solution to include any of thefollowing:

• Site Surveys

• Assessment of the existing scheme and implications for replacement (space issues, multi-core cable routes etc.)

• Network Studies – Power System Analysis

• Application of intended replacement scheme

• Assessment of network voltages for generator connections

• Network voltage optimisation

• Relay settings

• Scheme Design and Drawings

• Control Cubicle Design

and Build

• Marshalling Kiosk Design

and Build

• Site Installation

• Extensive team of experienced installation specialists

• Authorised for many UK DNOs

• Tap Changer Motor Drive Repair

and Upgrade

• Substitution of obsolete parts

• Maintenance of moving parts

• Optimisation of operation

• Commissioning

• Troubleshooting

• Investigation of scheme issues

• Extensive knowledge and experience with common problems

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Benefits

• Quality engineering – designed to last

• Core expertise – leaders in application of voltage control solutions

• Fewer schemes on fixed-tap – repair of old motor drives

• Accommodate more distributed generation – operational voltage control

• Quicker generation connection offers – system analysis for voltage control

• Reduce customer complaints – acceptable system voltages

• Reduce costs related to site alarms and call-outs – optimised network voltages and operational schemes

• Prompt resolution of issues – SME means lean and responsive

• Turnkey service – fewer suppliers to manage

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Tap ChangerMaintenanceThe tap changer is the component of thepower transformer which enables voltageregulation and is therefore critical for network management. Each tap changeroperation generates switching arcs oncontacts which leads to carbonisation of the oil and contact wear. Mechanicalcomponents, both internally in the diverterand also externally in the motor drive andshaft arrangements, are under stress during each switching operation. Regularmaintenance is therefore required.

Fundamentals are the exclusive UK & Ireland agent for MR (MaschinenfabrikReinhausen). Maintenance technicians have been trained at MR Germany on alltypes of tap changer and related devices. With many years’ experience and the direct support from MR, Fundamentals can offer a premium service for tap changer maintenance.

Features

The normal routine tasks for tap changermaintenance are as follows:

• Dismounting and mounting of the on-load tap changer insert

• Cleaning and inspection of the mechanical parts

• Visual inspection of insulation distances of the on-load tap changer insert and the oil compartment

• Parts replacement

• Replacement of the switching oil (unused oil with a breakdown voltage of > 50 kV/2.5mm, in compliance with IEC 60156)

• Determination of the contact wear

• Measurement of the transition resistors

• Inspection of the motor drive, drive shaft and protective surge relays

• Functional test – mechanical and electrical operation of tap changer

Benefits

• Optimisation of operating condition - reduce risk of tap changer problems

• Premium service - maintenance by qualified technicians according to manufacturer’s procedures

• 2-year warranty on parts – genuine spares from manufacturer

• Record keeping – maintenance history managed for customers

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Transformer Upgrade SolutionsWith an increasingly aged population of keyassets in the electrical grid comes increasingscope for refurbishment funded byoperational budgets as opposed toreplacement funded by capital budgets. The lifetime of power transformers can beextended by refurbishment involving theupgrade of components such as tapchangers, WTIs, PRDs, breathers, protectionand control schemes and relatedcubicles/kiosks.

Refurbishment of transformers is viable if the transformer itself is deemed to havesubstantial remaining lifetime. This can beassessed using diagnostic measurementssuch as DGA of the oil, SFRA, tan-delta etc. Many asset owners are taking suchmeasurements on a routine basis and are able to assign an asset health index totransformers. The health index may bedramatically improved by refurbishmentstrategies and can be much more economical and quicker than replacement.

The on-load tap changer is a key componentof the power transformer and is ultimately the only moving part in a substation. It is amechanical device and therefore requiresregular maintenance. Failure of a tap changercan result in replacement of the transformeritself due to the fact that replacement parts for the tap changer are often difficult tosource due to its age. This is expensive and can have long lead times.

Most OLTCs in the UK are the bolt-on designwhich lends them nicely to replacementwithout modification of the transformer itself.Maintenance-free tap changers can beinstalled on existing transformers in place of problematic or failed units to give decadesmore operating lifetime for the transformer.

This ultimately delays transformerreplacement, significantly reducingexpenditure and also removing therequirement for OLTC maintenance.

Fundamentals has experience in controlsystem refurbishment services wherecomplete tap changer control schemes are upgraded to modern standards.

The company has extended the scope ofservices to include replacement of othercomponents associated with powertransformers and can offer turnkey solutionsfor tap changer replacement (MR OLTCs) to cover the following:

• Site Surveys

• Engineering, Design and Drawings

• Site Installation

• Commissioning

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Features

Transformer upgrade services offered by Fundamentals include the following:

• Tap Changer Replacement

• All voltage levels and ratings• High-speed resistor and reactor types• Full range of tapping configurations• Oil and vacuum switches • Motor-drive replacement• Control system upgrade

• Transformer Temperature Control

• WTI and OTI replacements• Upgrade from electromechanical

to electronic systems• Kiosk replacements

• Breathers

• Maintenance-free breathers installed• Replaces conventional and

regenerative breathers

• Other Transformer Accessories

• Oil level indicators• PRDs• WTIs and OTIs• Monitoring systems

Benefits

• Reduce capital expenditure – save up to 75% of transformer replacement costs

• Modernise transformer – components upgraded to provide operational benefits

• Turnkey service – fewer suppliers

• Engineering support from MR –worldwide references for retrofit projects

• Standardised solution – retrofit packages suitable for many applications

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Fundamentals Ltd4 Hillmead Enterprise ParkMarshall Road, SwindonWiltshire, SN5 5FZ

Telephone 01793 847163Fax 01793 847245

www.fundamentalsltd.co.ukenquiries@fundamentalsltd.co.uk