Electrical Oil Services Life of A Transformer Seminar

Electrical Oil Services Life of A Transformer Seminar Dublin 2016 Proud to be part of

On-site Options for Transformer Insulation Management History Pressures on utilities and generators Looking after your paper insulation (water & acidity) Other parameters Take action – or not? In-situ treatment Proud to be part of

Standards referred to… BS 148: 1932 – 2009 – today known as “Reclaimed mineral insulating oil for transformers and switchgear – Specification” IEC 60296: 2012 – Unused mineral insulating oils for transformers and switchgear BS 5730 / IEC 60422 – Mineral insulating oils in electrical equipment – Supervision and maintenance guide Proud to be part of

Electrical Oil Services Some History Proud to be part of

A Little History Before Nationalisation 1926 Central Electricity Board 1947 British Electricity Authority 1954 Central Electricity Authority 1957 Central Electricity Generating Board 2000 Privatisation Proud to be part of

In 1941 “Unused Oil” could be delivered with a TAN Of 0. 2 mg. KOH/g (measure of acidity neutralisation) Today the limit is just 0. 01 mg. KOH/g (IEC 60296: 2012) Proud to be part of

A transformer purchaser could specify either “Class A” Or “Class B” insulating oil, depending on how much sludge He was prepared to put up with Proud to be part of

Electrical Oil Services Pressure on Utilities and Generators Proud to be part of

Pressures on utilities (Distribution Network Operators) Privatisation of the CEGB Harmony with Europe Reduced build quality Professional Purchasing OFGEM Regulatory review Extend asset life Spending restrictions Value for consumer Proud to be part of

Pressures on Generators Privatisation of the CEGB Harmony with Europe Reduced build quality Professional Purchasing “Dash for Gas” 15 year life of a transformer Base load – 2 shifting Corrosive sulphur Proud to be part of

Electrical Oil Services Looking after your Paper Insulation (water and acidity) Proud to be part of

Looking after your paper insulation (Water) Cellulose loves water Insulation is dried in the factory Site drying is costly and lengthy Don’t let your transformer get wet Proud to be part of

How much water is in a transformer? 145 MVA, 132 k. V HSPT GSU Tx Oil volume 34, 704 litres Water content 23 ppm at 50ºC Weight of oil = 0. 87 x 34, 704 litres = 30, 019 kg (paper = 3, 019 kg) Water in oil = 34704 x 23 ppm/10⁶ Or …… 0. 8 litres in the oil Assuming equilibrium conditions Proud to be part of

Proud to be part of

From a typical paper/oil equilibrium chart 23 ppm at 50°C equates to 2. 3% water in paper Assuming weight of paper = 10% weight of oil Then Water in paper = 3, 019 kg x 2. 3% = 69. 4 litres That’s over three 25 litre cans of water! Proud to be part of

Install some kind of molecular sieve Attention to breathers Fix leaks Dry air when oil is out Don’t leave covers off New transformers are dried to 0. 5% in the factory Proud to be part of

Proud to be part of

Looking after your paper insulation (Acidity) No such thing as an UNINHIBITED OIL Oxidation of oil leads to acid formation Acid attacks paper Transformer life is governed by the paper strength - maybe Permanent damage begins around 0. 1 mg. KOH/g Proud to be part of

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Electrical Oil Services Other Parameters Proud to be part of

And Other Parameters? • Dielectric Dissipation Factor (DDF) • Resistivity • Interfacial Tension • Breakdown Voltage Proud to be part of

Electrical Oil Services Take Action – or Not Proud to be part of

What next? What do these oil test results mean? Should I do anything? Proud to be part of

Importance of the transformer? Other DGA trends? Availability of spares? g? Sh ou do I ld hin t y n a Remaining paper “life”? Lead time for replacement? Opportunity to do other work? Proud to be part of

BSEN 60422: 2013 Property Voltage (k. V) 400/275 Good Fair Poor <0. 1 – 0. 15 >0. 15 132 <0. 1 – 0. 2 >0. 2 Water (ppm 400/275 20ºC) 132 <5 5 – 10 >10 <5 5 – 15 >15 DDF 400/275 <0. 1 – 0. 2 >0. 2 132 <0. 1 – 0. 5 >28 22 – 28 <22 Acidity (mg. KOH/g) IFT (m. M/m) All Proud to be part of

You could decide to take no action Proud to be part of

Electrical Oil Services In-Situ Treatment Proud to be part of

BSEN 60422: 2013 Property Voltage (k. V) 400/275 Good Fair Poor <0. 1 – 0. 15 >0. 15 132 <0. 1 – 0. 2 >0. 2 Water (ppm 400/275 20ºC) 132 <5 5 – 10 >10 <5 5 – 15 >15 DDF 400/275 <0. 1 – 0. 2 >0. 2 132 <0. 1 – 0. 5 >28 22 – 28 <22 Acidity (mg. KOH/g) IFT (m. M/m) All Proud to be part of

A“wet” transformer? Proud to be part of

Oil Change For acidity? Proud to be part of

In-Situ Regeneration Treats the insulation system “Deep Cleaning” effect Removes oxidation products Tool for helping extend life No outage necessary Less stress on paper insulation DBDS removed Inhibitor added at the end Proud to be part of

Site Operation (On-load) Primary degassed loop Recondition the oil Admit oil to adsorbtion beds Reactivate beds Repeat till finish Add inhibitor Proud to be part of

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132 k. V DNO Transformer (OFGEM) 90 MVA Installed 1963 38, 710 Litres of oil DP of paper 500 Acidity 0. 28 mg. KOH/g IFT of 13 DDF 0. 063 m. N/m No history of faults DGA “normal” for age Proud to be part of

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132 k. V DNO Transformer (OFGEM) 60 MVA Installed 1959 40, 915 Litres of oil DP of paper 523 Acidity 0. 27 mg. KOH/g IFT 13 DDF 0. 072 No history of faults DGA “normal” for age Proud to be part of

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66 k. V Steel Works Transformer 10 MVA Installed 1959 17, 000 Litres of oil DP of paper 420 Acidity 0. 24 mg. KOH/g IFT 22 DDF 0. 23 No history of faults DGA “normal” for age Proud to be part of

Proud to be part of

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Electrical Oil Services General Enquiries Tel: +44( 0)845 602 1003 www. eosl. co. uk Proud to be part of