This week, the National Energy System Operator (“NESO”) published its final report into the North Hyde substation fire on 20 March that caused a local power outage which cut supplies to over 71,500 homes and businesses including nearby Heathrow Airport.
The airport was without power for most of the day, disrupting thousands of flights and having a global impact as incoming flights were diverted and outgoing flights were cancelled. Thankfully there were no reports of serious injuries or fatalities.
In this blog I will review the report, explore some of the issues raised around maintenance and asset lives, and consider whether Ofgem should be more proactive in its oversight of the management of network asset condition.
What happened?
According to the report, at 23:21, one of three supergrid transformers at the substation owned and maintained by National Grid Energy Transmission (“NGET”), a subsidiary of National Grid plc, tripped and was later confirmed to have caught fire. Soon after, the adjacent transformer also tripped.
A third transformer at the site was further away and was not affected other than it was unable to be used as long as the substation was de-energised while the fire was tackled. The site layout is described in my previous blog on the incident.
Transformers are some of the most important pieces of equipment on the grid – they allow electricity to be moved in bulk over long distances with minimal losses, by increasing the voltage.
However, as high voltages are dangerous, and are unsuitable at the point of use of the electricity, voltages are stepped down before they reach the consumer. Transformers are used to make these voltage transformations.
Transformers consist of wires wrapped around a metal core. These windings are subject to heating, with heat degradation potentially leading to short circuits. For this reason, they are cooled, through the use of oils which are circulated round the windings. The oils are electrical insulators to prevent shorting between the windings, and are thermally stable ie they don’t freeze in winter. But they are highly flammable, so in the event of arcing, they can explode.
The part of the transformer that failed at North Hyde is called a bushing which is essentially a sleeve that allows cables to enter and exit the metal oil tank without touching the walls of the tank and becoming earthed. Unfortunately if moisture gets inside the sleeve, a short circuit can occur, leading to arcing, and evidence of this was observed in the debris from the fire.
As noted in my previous blog, Heathrow lost power when the fire broke out and closed. Some flights resumed at 7pm on 21 March but the airport did not resume normal operations until Saturday 22 March.
The NESO report tells us a bit more about the Heathrow grid connections and but the substations that actually supply it are simply referred to as A, B and C.
What I didn’t mention in my previous blog as I didn’t discover it until later, was that there had been a very similar substation fire at Atlanta airport in 2017, as a result of which US airports improved their energy resilience. Heathrow could and should have learned from that incident and not referred to the North Hyde fire as being “unprecedented”.
Track record of delayed maintenance
This particular transformer at North Hyde had known issues: moisture had been detected inside the bushings as far back as 2018 at levels NGET’s guidance said indicated “an imminent fault and that the bushing should be replaced”. The technical guidance dictated that following such highly elevated moisture samples, the asset should remain out of service until the bushing can be replaced, or mitigating actions put in place.
“While the reading was recorded, the mitigations appropriate to its severity, as set out in National Grid Electricity Transmission’s relevant policy, were not actioned at the time. The controls in place were not effective and failed to identify subsequently that action had not been taken in relation to the elevated moisture reading. This review finds that there were other opportunities which, had they been pursued, could have caught the issue. Instead, the elevated moisture reading went unaddressed,”
– NESO North Hyde Review – Final Report
A forensic examination of the remains of the bushings after the fire showed evidence of moisture ingress on the C-phase high voltage bushing that suffered the catastrophic failure. Such evidence of moisture ingress would not have been visible externally and therefore only became apparent after disassembly and forensic analysis after the incident.
The forensic analysis also found evidence of arcing erosions within the C-phase high voltage bushing. Arcing erosion is the damage caused by electrical arcs, which normally occurs due to electrical faults or contamination, including by moisture ingress. This damage can lead to the gradual degradation of parts of the bushings, possibly leading to reduced insulation resistance, potential short circuiting and ultimately, bushing failure.
Phases A and B of the high voltage bushings did not show any evidence of arcing erosion, supporting the case that the fault was on the C-phase only and had arisen as a result of moisture ingress. NESO and the forensic engineers that inspected the remains of the bushings concluded that due to the extensive damage to the transformer it is unlikely that any greater certainty about the exact cause of the fire can be achieved.
So there had been evidence in 2018 of moisture within the bushing to such a degree that the transformer should have been taken out of service while the bushing was replaced, but this work was not carried out, and some seven years later, the post-fire examination found evidence that there had indeed been internal damage to the busing consistent with moisture ingress.
In addition to the failure to address this equipment fault, basic maintenance of the transformer was overdue and had been consistently put off, and fire suppression equipment at the substation was found not be to working in 2022. A further inspection in 2024 showed it still didn’t work and repairs had not been carried out at the time of the fire, although London Fire Brigade suggested it would not have made much difference had it been working.
In 2023, NGET decided to extend the interval between basic maintenance from four to five years, and for major maintenance from 11 to 15 years. The most recent basic maintenance of the transformer had been in 2018, so it was well overdue on both the old and new schedules.
NESO’s report sets out the delays to the basic maintenance for the North Hyde transformer, which was overdue by the time of the fire. Multiple attempts had been made to schedule this maintenance, none of which went ahead:
- A planned outage to enable maintenance had been scheduled for 4 October 2021, but was delayed due to NGET’s reprioritisation for other higher risk works
- A further maintenance outage was scheduled for 10 October 2022, but shortly before the outage window, an issue on another transformer at the substation meant it could not go ahead. NGET said it was unable to replan the maintenance within the next outage planning year, which runs from April to March
- From December 2022 onwards, a number of mitigating actions on the transformer were implemented, as it was known that the basic maintenance would be overdue by March 2023 (under policy that was in force at the time). These included carrying out a Radio Frequency Interference condition monitoring survey and a thermovision inspection every three months. Whilst these would not have identified moisture in the C-phase bushing, they may have identified issues caused by moisture ingress
- Maintenance was replanned for 2 September 2024, but did not occur as an equipment defect at the nearby Iver 275 kV substation meant that the North Hyde 275 kV substation was needed to secure the system and could not be taken out of service
- The next planned outage to enable maintenance was scheduled for 19 May 2025, but even this had been moved back to 17 November 2025 to optimise NGET’s overall resource availability.
NGET’s maintenance policy targets 85% of assets being within their normal maintenance cycle – as of May 2025, 697 of 805 transformers (87%) were within the maintenance frequency target, just meeting the standard. However, NESO does not comment on whether there is any further requirement in terms of the length of delays to maintenance one a site is outside the cycle.
In this instance, basic maintenance was put off four times, and at the time of the fire, had not taken place since July 2018, ie in six years and 8 months – 20 months after it should have been carried out under the newly extended policy, which should be a third way through the next maintenance cycle!
While oil sampling of the bushings to detect the presence of moisture is not included as part of basic maintenance and is planned separately, NESO believes that had the basic maintenance been conducted, NGET could have taken the opportunity of the transformer being out of service to conduct oil sampling, which may again have brought attention to the elevated moisture reading on the C-phase bushing.
There are also advanced online continuous condition monitoring solutions which could have enabled detection of partial discharge or arcing prior to the incident. These are deployed in certain circumstances on the transmission system already. In the RIIO-2 price control period Ofgem allowed NGET to allocate £18.65 million, plus indirect costs, to investments in such monitoring. The criteria for deploying this technology are based on an assessment of factors such as asset population, asset age and historical performance data. This technology was not in place in North Hyde, where NGET had determined that the criteria were not met.
NESO did not comment on whether this decision was reasonable given the actual age of the transformer, records that it had been operating at above its rated capacity and the fact that it was located in a highly populated area where the grid was highly congested. Meaning that not only was the asset vulnerable, its failure was likely to have a significant impact on consumers.
The sequence of events at North Hyde suggests a wider, systemic problem with delayed maintenance, and little follow-up in terms of the risks associated with these delays.
Another concern that was not mentioned in the NESO report but that is relevant is that the substation had been identified in a 2022 report for the London Assembly as having peak utilisation in 2021-22 of 106.2%. This is likely to have continued as the grid in west London is highly congested.
NGET’s approach to asset life management
The NESO report identifies that the transformer was installed in 1968, making it 57 years old. NGET believes that transformers can last 60-65 years, but a 2024 report for energy regulator Ofgem by Cambridge Economic Policy Associates (“CEPA”) found that NGET had much wider asset life parameters on average than its peers in the UK (such as the Scottish transmission owners). Despite the North Hyde transformer approaching NGET’s end-of-life window it had not identified the unit as being close to end of life and on a pathway to replacement.
The CEPA report was commissioned to ascertain whether the average asset life of 45 years used for the purposes of depreciation in RIIO-2 remained appropriate. In some ways, this is the first problem – the assessment of asset life should be from a physical performance rather than financial perspective. And unfortunately the question about real life weren’t really asked:
“Given the large number of assumptions inherent in any estimation of technical asset life data and the fact that this data was not part of formal business plan submissions, the average figures resulting from our analysis should be seen as an indication of direction of travel, rather than detailed precise estimates,”
– Economic Lives of Electricity Transmission Network Assets, CEPA
CEPA noted that “Compared to the 2010 analysis, National Grid Electricity Transmission (NGET) and Scottish Hydro Electric Transmission (SHET) both report an increased range in statutory asset lives across their asset portfolio – the range presented by NGET has widened from 15-60 years to 15-100 years, and the SHET values now span 5-80 years (from 10-80 years in the 2010 data set). However, Scottish Power Transmission (SPT) now use a single figure of 40 years, compared to the range of 30-60 years in the 2010 study.” NGET made significant increase to its determination of asset lives since 2010 – has this been subjected to real scrutiny?
CEPA went on the say that “based on the central estimates provided by the network companies, the weighted average technical asset life for GB as a whole was estimated at 55 years”.
NESO’s report into the North Hyde fire stated that NGET has assigned an End of Life (“EoL”) score of 12.7 out of 100 for the defective transformer (0 is for new assets and 100 is for ones that have reached the end of their lives). It is difficult to see how a transformer that was 57 years old and not maintained in line with NGET’s policy, with faults that required it to be immediately removed from service for remedial works could possibly have such a low EoL score unless there had been some major overhaul at some point in the past which was not revealed buy the report.
“On coherence and justification, the plan lacked a clear thread particularly around NARM [Network Asset Risk Metric] and asset management plans. There were contradictions between the load plan and non-load plan which suggested a lack of long term planning and meant that the overall plan lacked coherence in places,”
– NGET RIIO-3 draft determination, Ofgem
Ofgem has identified issues with asset life in the RIIO-3 process. It says that non-load replacement capex plans have poor justifications and high costs, and while non-load refurbishment capex was deemed to be better evidenced, there were criticisms that no schemes were priced below the benchmark. By contrast the load related capex plans were deemed to be comprehensive and acceptable.
(“Non-load” capex refers to capital investment in existing assets — replacing, refurbishing or reinforcing infrastructure such as transformers, switchgear and cables to manage asset health, safety and reliability. “Load” related” capex, by contrast, is driven by changes in demand or new customer connections — for example, building new substations or upgrading existing ones to accommodate additional load or generation. Both types of capex may involve similar physical equipment, but the driver and regulatory treatment differ.)
This suggests a couple of things to me: has NGET prioritised load over non-load projects in response to some perceived regulatory preference, or is Ofgem applying a different standard to these projects reflecting its own priorities relating to renewables connections. It seems strange that a company would be good at assessing cost for one type of capex but not another where the underlying assets are similar (ie network equipment rather than real estate or software).
Was Ofgem asleep at the wheel?
This all raises questions about Ofgem’s role. While it has been critical of NGET’s business plans in respect of aging infrastructure, its response lacked teeth. Why did Ofgem not insist that asset lives be more rigorously analysed and that maintenance of older critical equipment was carried out on time? Was Ofgem’s focus on renewables connections a factor in the approach taken by grid owners to legacy equipment, knowing that consumers can’t pay for everything at once during a cost-of-living crisis?
Ofgem rejects this criticism and says it has never told regulated firms to downgrade investment in legacy assets in order to prioritise renewables connections. But connections are a huge focus for the regulator, and it would be naïve to think that regulated firms would not take this into account when developing their business plans. (Out of curiosity I searched the words “connections” and “asset” on the Ofgem website. “Connections” had 1804 hits while “asset” had 681 hits.)
Ofgem’s job isn’t simply to rubber-stamp investment plans, it’s to challenge asset risk management and resilience plans. But when you dig into it, Ofgem didn’t rubber stamp NGET’s business plan – in RIIO-2, the current price control period, it cut non-load capex by a third from £2,650.9 million to £1,765.8 million (the draft determination had suggested a 72% reduction!). The load related determination was actually higher NGET’s request – this is money for connecting new generation, primarily renewables.
Ofgem said that NGET’s engineering justifications were insufficient which is why it had proposed a 72% reduction in the draft determination. Following improved disclosures by NGET, the budget was revised upwards, but was still materially lower than NGET had requested. This exposes a fundamental flaw in the price control mechanism: Ofgem wants to endure networks are delivered at the “lowest possible cost to consumers”.
I strongly oppose this objective – a more appropriate measure would be “lowest reasonable cost”: first of all how can you ever be certain that something is the lowest possible cost, and secondly this will bias decision-making against expenditure, possibly inappropriately. It certainly biases towards delayed expenditure due to uncertainty over whether it is the lowest possible cost solution.
So Ofgem’s response to NGET’s insufficiently detailed business plan was to assume that anything that could not be well evidenced should not be done. The bias was towards avoiding cost rather then being prudent with asset replacement. It is probably at the heart of the difference between a nationalised and privatised industry – before privatisation, investment was done when the network owner thought it was appropriate. Sometimes it was premature, excessive or demonstrating poor cost control, but it tended to be an asset-first approach. Now we have a cost-first approach that prioritises short-term cost to consumers.
Specifically in relation to supergrid transformers (“SGTs”), in RIIO-2 Ofgem said:
“in Draft Determinations, we proposed to reduce NGET’s planned SGTs from [redacted] to [redacted] and to reject the rest as we viewed it uneconomic and inefficient to replace healthy assets. NGET provided significant additional asset health and project data to support their request. This included highlighting assets which had rapidly degraded from their originally reported position. We note that NGET’s pessimistic assumption of risk increases are generally driven by asset family issues, which we note are difficult for us to assess. However, we accept and approve the additional 8 units highlighted by NGET as high-risk assets which warrant replacement. We have also decided to approve 3 Static Compensator Transformers, which NGET evidenced as high risk.”
It’s also interesting to consider the costs of the price control itself – Ofgem wants detailed justifications from NGET and other network owners in respect of expenditure. This means NGET and other need to spend significant time and resources to prepare detailed plans relating to the thousands of assets they own, and Ofgem needs to hire engineers qualified to assess these plans and determine whether the works are justified. Industry complains about the regulatory burden – the price control is an example of this, state owned enterprises suffer from poor cost control to the detriment of tax-payers while privatised monopolies have a profit imperative to the detriment of bill-payers. However, Ofgem should not seek to ensure the lowest possible costs as this risks a culture of delaying necessary investments and may result in higher long-term costs anyway.
Ofgem has now announced an investigation saying it expects network companies to “properly maintain their equipment”. The words “horse” and “bolted” spring to mind – the regulator should be monitoring this continually, not just issuing fines after things have gone wrong.
Regulatory reform is needed – simply fining people after a fault is not enough
We need urgent action: Ofgem must demand a comprehensive review of all legacy transformers and other critical grid equipment, enforce swift maintenance or replacement. It also needs to be far more proactive about ensuring grid owners are assessing asset life appropriately and that their maintenance procedures are both rigorous and properly adhered to in practice.
I suggest an approach similar to a controls-based financial audit: Ofgem engineering teams would periodically (eg every 2.5 years being half of the price control period) inspect all asset management policies, review board minutes and other evidence relating to policy changes, and select assets from each major asset class on a random basis for further analysis: what do the records say about these assets, is the maintenance up to date, does the physical condition of the assets correspond to the documented condition etc. They should also review things like site security.
They should also instruct network companies to identify any assets that impact other critical infrastructure, or would expose people or property to high levels of risk were they to fail, and consider whether a stricter maintenance regime would be appropriate. For example, a substation explosion could be more dangerous in some locations than others, for example if located close to a school.
More broadly, I recommend that Ofgem and other regulators create teams whose sole job it is to think about all the ways that disaster could strike their regulated firms. These could be errors, mundane failures or deliberate sabotage or other criminality.
- What if a major supplier goes bankrupt unexpectedly due to audit failures (it happens)?
- What happens if network assets are improperly maintained?
- What happens if NESO control room software or hardware fails or someone hacks the NESO control room?
- What happens if there is corruption within regulated firms so investments Ofgem thinks have happened did not, or were done with inferior materials?
- What happens if there is corruption within Ofgem teams?
- What happens if a third of the CCGT fleet retires by 2030?
- What happens if there is a massive solar flare or someone targets networks with EMP devices?
- What happens if a systemic fault is discovered in any type of network equipment similar to the stress corrosion issues in the French nuclear fleet, eg accelerated thermal aging or water treeing in cross-linked polyethylene power cables or new synthetic ester transformer oils degrade faster than expected?
The impact of solar power on transformers is an under-discussed risk. Rapid load transitions caused by solar PV ramping, particularly at sunset can impose thermal and electrical stresses on transformers, and there’s growing concern that legacy transformer design models may not fully account for the new stress regimes introduced by high-penetration solar.
During the day, large amounts of solar reduce the demand seen by distribution and transmission transformers, even reversing it in some cases (net export). Many transformers run lightly loaded or with reversed power flow. At sunset, solar output drops quickly over ~30–60 minutes. Grid-connected load reappears suddenly as solar generation ceases, and transformers experience a sharp increase in load current, often accompanied by a voltage dip and reactive power swings.
This is especially stressful when air temperatures are still high (eg summer evenings), reducing the transformer’s cooling effectiveness or when there’s a mix of PV and fast-reacting loads (EV charging, air conditioning) causing both electrical and thermal shock.
This impacts transformers in a number of ways:
- Thermal cycling fatigue: repeated heating and cooling stresses insulation, gaskets, and conductor materials. If the evening ramp is steep and daily, it accelerates aging of winding insulation and can promote oil degradation
- Overfluxing risk: voltage dips and high loading can lead to overfluxing if not properly managed, stressing the magnetic core
- Mechanical stress on tap changers: frequent voltage variations at sunset may trigger repeated tap changes, increasing wear
- Harmonic distortion and flicker: in areas with a lot of solar and switching inverters, high-frequency harmonics at sunset may add further heating.
There could be a tipping point of solar penetration connected to substations above which this becomes a problem, and this could vary by location and transformer type.
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There’s a lot we can and should learn from the North Hyde incident. To its credit, Ofgem is showing itself to be open to this, and to engaging with me and others in how it can improve. The test will be whether it takes a more pro-active approach to managing risk within the sector, or simply continues with the current MO of reacting with fines and new rules only after things have gone wrong.
The bushing moisture was discovered in 2018, presumably during the 2018 maintenance window., at which point imminent failure was predicted. So why wasn’t it replaced then?
Good analysis.
“Heathrow could and should have learned from that incident and not referred to the North Hyde fire as being “unprecedented”.”
In my ~60 yrs as an engineer [ mechanical … I’ve never been civil (:-)) ], I’ve noted that most “unprecedented” events have happened before.
“Unprecedented” is widely used by incompetents as a get out of jail card, or to promote a money making scams ( like net-zero ) from cyclical events.
Enjoyed your talk on ICSF last month, it generated a good discussion.
Keep up the good work
john
I bet Ed Milliband would not understand 90% of this.
I do not think this comment adds to the knowledge of the readership of Watt Logic. It might be OK on some (but not all) Facebook pages or similar social media forum but not here.
OFGEM, since Jonathan Brearley was appointed CEO have lost sight of their original remit to ensure that customers are getting a good deal, that is cheap reliable electricity and gas, He was involved with Baroness Worthington in writing the draft of the climate change act (2008), putting an eco loon in charge of our energy regulator is tantamount to putting the fox in charge of the chickens. I believe that if OFGEM had never existed our electricity and gas systems would be in a better state than it is now, a functioning competitive market, the price cap is really stupid idea.It is about time OFGEM stood up to Ed Miliband’s mad dash for Net Zero and told him that it is not possible to achieve in the time scale proposed. When you than add in all the technical issues, no spinning inertia, solar arrays connected to the low voltage distribution network, reactive power provision and absorption, and now lack of maintenance of the old infrastructure to concentrate on new pylons to get offshore wind to where it is needed, We are heading for a disaster, someone high up in the NESO has to confront Miliband and tell him, Fintan Slye over to you.
Always find it mildly amusing when right wingers call for tougher regulations and oversight.
I suggest this is not a case of left or right.
Perhaps the HV types could do the job they have done for more than a century?
Perhaps the ivory towers should be reconsidered?
There are plenty of good protocols already, but if ‘smart money’ says ‘no’, then this is the result.
Planned incompetence.
I’m calling for better regulation not more regulation
Why is this website letting me comment as someone else?
Semantics,, tougher, better, more. Largely the same meaning in this context. I saw this oversight system a very small scale in my first job. Outsourced facilities for a hospital. Company coincidentally failed spectacularly leaving loads of people out of pocket. It introduces a whole layer of pointless middle managers who don’t understand what is needed. Who haven’t worked on the tools or anywhere near them. Imagine how this scales to nget size. No amount of better oversight is going to properly change a model that fights for the opposite. There aren’t enough good people to do this. Isn’t wasted spend on consultants and middle management something to avoid? And is this the model to achieve the transformation needed for net zero? Think not from what your highlighting here.
Was an exclusion zone set up around the transformer in 2018? The focus has been on loss of supply but what about the danger to staff and contactors. A HSE prosecution may focus policy more clearly than vague OFGEM penalties. We should focus on physical reality not financial assessments.
Very good point when we had busbar chambers failing on 1950’s 33kV switchgear we put in place no entry to the substations when live now admittedly that was within buildings where the consequence of failure was more significant.
Another question is the status of the removal of Poly-Chlorinated Biphenyl transformer oil, supposedly finished this year, an onerous process akin to asbestos removal?
OFGEM, since Jonathan Brearley was appointed CEO have lost sight of their original remit to ensure that customers are getting a good deal, that is cheap reliable electricity and gas, He was involved with Baroness Worthington in writing the draft of the climate change act (2008), putting an eco loon in charge of our energy regulator is tantamount to putting the fox in charge of the chickens. I believe that if OFGEM had never existed our electricity and gas systems would be in a better state than it is now, a functioning competitive market, the price cap is really stupid idea.It is about time OFGEM stood up to Ed Miliband’s mad dash for Net Zero and told him that it is not possible to achieve in the time scale proposed. When you than add in all the technical issues, no spinning inertia, solar arrays connected to the low voltage distribution network, reactive power provision and absorption, and now lack of maintenance of the old infrastructure to concentrate on new pylons to get offshore wind to where it is needed, We are heading for a disaster, someone high up in the NESO has to confront Miliband and tell him, Fintan Slye over to you. (I tried posting this previously but it never made it, if it is in twice then apologies)
Thank you for this very helpful analysis, Kathryn.
An excellent article, focusing on importance maintenance and testing. Highlighting the struggle to inform management on the value of maintaining aging electrical equipment.
One of the problems I found with Risk Assessing maintenance and testing was, to many people seen it a a way to delay maintenance. Saving money, but failing to grasp the cost of failure.
First a brief explanation. I was responsible for the Electrical system of an offshore Oil and Gas installation. The system comprised of
3 off 24.5 Mw GE frame 5 single shaft generators driving 24 Mw Brush (manufacturer) generators
10 11Kv drives 1 to 5 Mw DOL starting
1 14 Mw VSD driving compression train
1 24 Mw GE Frame 5 2 shaft turbine, driving a compression train
2 off 5MVA 11Kv to 3.3Kv transformers supply 16 off 3.3kv motors, seal oil, ballast and sea water lift pumps, production critical
4 off 1 MVA 11Kv to 415V auxiliary boards.
We had a failure of one of the 5MVA transformers. Installation could be run on one
I took the following steps before platform restart. Tested the remaining transformer including breakdown voltage testing of the Oil.
Asked the onshore support to investigate the possibility of sourcing for hire a transformer. Ideally in the same vector group. But was willing to accept if needed, would require a shut down to transfer load.
Onshore group found DGA Dissolved Gas Oil Analysis which can help identify problems within the transformer. A survey was organised.
Onshore group sourced a suitable transformer. Long story short the “management” declined to spend the money.
I explained the following
The remaining transformer was the same age manufacture and duty life 1975 (this event was circa 2000)
If the second transformer failed.
The following would occur
Seal oil pumps for the compression trains would fail. Tripping the gas compression trains. Shutting down gas export.
Sea water lift and cooling water pumps would trip. approx 10 minutes later main generation would trip due to high lube oil temperature. Shutting Down Oil production.
Ballast water pumps would trip, result we could not take oil from the second platform in the field.
We were exporting around 120mmscfd gas. Producing 100K barrels of Oil
This got the management attention. And funds were approved. To often they do not understand power systems. They work 24 hours day for years. No one in the management considers them. Out of sight out of mind.
DGA was carried out and showed problems of heating with in the transformer.
Using both this technology and thermal imaging. Problem was traced to the tap changer contact one which was over heating. Tap changer on the system are set at start up, they are not auto.
There was an article about the combination of analyses and thermal imaging in one of the Electrical magazines.
A replacement tap changer was sourced from Brush
The temporary transformer was commissioned.
The tap changer was replaced.
I spent more time trying to convince the management on the importance of maintenance and testing. A long thankless struggle
Ps Im a foundur membur o the wurlds wurst spelin klub
Thanks you for your comment. I was accused on LinkedIn of writing total rubbish in my Telegraph article which was a shorter, dumbed down version of this (and some complaints about a chart I can’t see as I think they took it out and didn’t provide in any case). Apparently heating isn’t a problem in transformers!
PS. Im an ad hok membur ov yore klubbe
Interesting report. Basically outdated design, longevity/resilience not reviewed nor actioned, poor/ineffective maintenance strategy. A more professional approach would be to engage an effective life-cycle management process that should/would have mitigated this risk. If NESO truly want to learn and improve they should embrace lean thinking and the characteristics of the machine that changed the world – the Toyota Production System which is based on Kaizen & the continuous application good practice
Was routine maintenance as slipshod as this in the old days of the CEGB? Somehow, I doubt it.
It’s bad enough to realise, post the Spain blackout, that we have spent the past 20 years building out weather-dependent wind and solar farms which are fundamentally incompatible with how the grid was designed to operate, but now we realise that due to dangerously neglected maintenance, random plant failures which could trigger a Spain-like cascading shutdown could happen at any time.
Sometimes I feel sorry for everyone involved in the national energy and infrastructure industries, including our Uniparty politicians, because they have been set an impossible Net Zero task by their globalist overlords. But then I remember how they dissemble and lie to us all the time and all my sympathy evaporates. They could after all refuse to comply, as I hope Reform will.
Thank you Kathryn for threading the readers through the next of TLAs and FLAs.
There is a temptation to say industry does not manage assets well ,and in same cases this is true.
However, what Ofgem, NESO and NGET got up to is sad – few HV electrical types will find anything here unexpected when the system is entirely driven by accountants.
Large transformers are expensive and rarely standard, so take time to order / build / commission.
To see such blatant abuse of such an asset is terrible.
As I write, a very small transformer is doing its job – so old and completely unmaintained that the paint has been washed off..
It is an emblem of ‘not my job, could not care less’.
It’s hard to unpick the price control information…was NGET sloppy with non-load assets but not with load assets, or was Ofgem biased against non-load capex? Or both?
We can see from the water sector what happens when regulators sign off inadequate business plans because they avoid short term costs to consumers rather than thinking whether the regulated firm should be granted higher allowances and telling them to develop a better plan. Refusing funding on the basis that planned costs were not lower than some benchmark does not address whether the work is necessary. Regulated firms aren’t going to do work they’re not being paid for
Utility Week covered the draft RIIO-3 determinations today. It seems my concerns are shared:
“…..It is a point echoed by iTower Analytics founder and former Cadent analytics and insights manager Daniel Heller, who says that it will be the “main frustration” from the electricity networks in response to the draft determinations. “That’s where the frustration from them [TOs] will come, because the biggest burden to any of their networks is the operational expenditure which they go through to maintain the existing network,” Heller says. “It’s fantastic to invest in a shiny new car or new appliances, but if the rest of your house is falling down then you’re not investing in the right way, and it’s not the right approach.”
He adds: “It’s full steam ahead for the shiny new stuff to deliver Clean Power 2030, which is absolutely essential. But look closer, and you see a worrying trend. Ofgem is squeezing the funding for the boring but crucial stuff. Even as electricity transmission gets billions for new projects, its funding for core maintenance and asset health is being cut with networks being pushed to drive efficiency. At the same time, the gas networks, are being asked to manage a slow decline on a reducing budget where operational pressures still remain.””
https://utilityweek.co.uk/digital-weekly/digital-weekly-ofgems-riio3-rulings-unpacked
This is a key point
All the money for wind farms, solar, there grid connections, the shiny new, sexy stuff .
Squeeze the life out of the existing assets
How often will we have seen similar approaches, in the world of asset management.
‘You do not need to do that maintenance then, we can keep on running’
The report just leaves a load of unanswered questions.
The bushing when tested in 2018 was Cat 1 “‘an imminent fault and that the bushing should be replaced” but wasn’t. The report then completely ignores why, what the process should have been and why and how did it fail.
Fire brigade on site 6m after call out 7m after receiving report. Couldn’t start tackling the fire until 0536 until permits were issued – really!
Report doesn’t address how the control room managed the incident directly which seems a central matter to me neither how the whole incident was managed between NG and LFB. The reports skirts round Heathrows issues and cites national security yet it divulges NGs arrangements. Anyhow I guess they shouldn’t get into the politics of that given they are the root cause although to me it was still a credible failure scenario that Heathrow should have been able to manage.
Quite frankly im quite gobsmacked by what i read and NG now seem along way away from the CEGB & Area Board engineers i knew and worked with 40 years ago.
“that Ofgem and other regulators create teams whose sole job it is to think about all the ways that disaster could strike”….
What happens if there’s political interference with the regulator
What happens if there’s political interference with the regulated companies
What happens if there’s political interference in the market
What happens when there’s an unrealistic political dictat
Political posturing by the incumbent government is a real risk, exactly how you assess that is an open question but you can’t do it by way of a regulator that’s biased by the current political adgenda. Adgendas change, does it take an actual disaster to induce a course correction?
At some point you have to wonder how many assets could be replaced for the cost of explaining why they need replaced to the regulator – especially when the regulator then needs to hire in expensive consultants to (try to) understand the explanation.
and… “Ofgem has now announced an investigation saying it expects network companies to “properly maintain their equipment”.” is totally at odds with [Ofgem] “had proposed a 72% reduction”. You can’t ‘properly maintain’ anything when you don’t have control of your budget and the regulator can arbitrarily reduce it.
I get it that there’s a balance to be sought, but at some point you have to start wondering if re-nationalisation and consequently eliminating an ineffective regulator wouldn’t be the lesser of two evils. Yes that may come with the risk of political interference, but would that be worse than what we have now?
In a lot of way it’s not simply about the risk. Regardless of risk what’s the impact of a blackout like Spain – how you look at the risk might change if you have a better understanding of the impact
There’s a somewhat seperate argument to be had on maintenance schedules, but could you imagine the outcry if someone suggested reducing the number of cars MOT’d each year by 72% ? The problem there is that buisness models have been built around a mandated schecule whether it’s realistic or not and what the actual risk is, still I don’t think you can increase the maintenance period from 11 to 15 years without consequence, especially as the asset ages. If anything you may want to consider increasing the inspection/maintenance frequency with age. You certainly shouldn’t tie anything to financial outcomes/benchmarks/periods though as those tend to be ignorant of the engineering realities.
The flip side is that trying to judge a 60 year old asset by current standards, that a new asset would meet, may be totally futile. However if the risk, and ultimately the impact, is minimal does it actually matter? Problem is that humans in general are not particularly good at probabilities and risk assessments, MBA’s and beancounters less so.
The report by NESO raises more question than answers.
I was once responsible for maintenance on a high hazard chemical plant and in my youth a distribution electrical engineer. The fact that HV bushing was not flagged up and dealt with pronto, is inexplicable! That is incompetence of a high order and would raise questions about the values and standards, of the senior people in the electricity company.
When on the chemical plant, we had the Health & Safety Executive breathing down our necks all the time, with the EA on top. It looks like the regulation and oversight is lacking.
Good summary of the situation Kathryn
Kathryn; another excellent report, thank you. My electrical knowledge is rather scanty so I really appreciate the explanations and depth of information that you provide.
One small query: you state “During the day, large amounts of solar reduce the demand seen by distribution and transmission transformers, even reversing it in some cases (net export).” Does this apply to all transformers across the sysem? I ask because I have read elsewhere that transformers are generally not “reversible” unless specially designed. Thanks.
Hi all…an in depth analysis of my world from the 1960’s thro’ to 2001 experiencing all aspects of the transmission network. Kathryn teases out many of the issues over the years particularly across the nationalised CEGB/National Grid transition (1990) an amazing report, the terminology so accurate & familiar. I find the asset first approach (afa) v cost first approach (cfa) interesting.
There was a major transfer of 132kv assets to the regional distribution companies (RDC’s) around 1970 involving 1000’s of miles of overhead lines, substations (S/S’s), transformers, circuit breakers (CB’s) etc.
I recall previous to the transfer (1960’s) GEGB transmission installing 100’s of new bulk supply points (132/11kv S/S’s) Rumour at the time suggested that the RDC’s were pushing for these new installations rather than reinforcing their own 11kv network. Somewhat borne out by the subsequent very low demand registered post commissioning. There are many very interesting points in the report, but I tend to focus on afa v cfa. In those early years with CEGB transmission we were often accused of cheque book engineering, missing or delaying an outage related statutory air inspection (SARI) or suspect oil sample results, requesting an outage for tree cutting, cardinal sin’s.
These were the days of s/s attendents, overhead line wardens, who took pride in their task & keeping engineers like me informed.
There was always co-operative creative tension between we in the field & System Operation’s (S/O’s) now NESO. The latter always pushed for an unrealistic intact super-grid network at 2 years out, whilst we were burdened with new construction, uprating, OHL Diversions, repairs, routine maintenance in our outage requirements working up to the final outage plan (April to March).
Could it be that the alleged over maintenance, early replacement of assets etc. pre 1990 which has served us well over the past 30 years is finally beginning to show signs of wearing out ?
Bringing me back to the “afa v cfa” which I would argue is a small price to pay for where we appear to be today.
Barry Wright, Lancashire.
That’s a really comprehensive and thoughtful analysis. At the end of the day, the importance of the quality of leadership of our key institutions is really the deciding factor. Sir Walter Marshall would never have allowed things to deteriorate in the way they have – whether he were running state industry or a commercial business. I can think of companies that have been led by engineers who were sometimes accused of gold plating – but the result was that their operations kept going when the going got tough, and it produced superior returns overall: they were also typically very canny about the timing of investments. But Brearley at OFGEM and Slye (who was after all in charge at NGESO during most of the period of neglect) are not cast from that mould.
Lions led by Donkeys….Brearley at OFGEM has let the consumers down, by going all out for intermittent renewables, instead of keeping prices down.