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Substandard Oversized Joints Identified With IMCORP Factory Grade® Technology

Guest Article: IMCORP 

uploaded by Natalie Lundie – Thorne & Derrick Supply Chain: Marketing Lead

IMCORP is a provider of underground power cable reliability services for medium and high voltage (5kV to 500kV) power cable systems for both aged and new cable installations.

IMCORP’s Factory Grade® technology will access MV HV Cable Systems, identify cable systems in need of rehabilitation allowing the customer to ultimately restore the cable system to like-new status.

OVERVIEW

Oversized joints with installation errors are identified with the Factory Grade® technology.

CHALLENGE

Identifying root cause of multiple cable joint failures and substandard performance after a Factory Grade® assessment.

RESULTS IMCORP’s

IMCORP’s Factory Grade® technology effectively identified incorrectly sized joints and provided critical information to improve product selection and installation practice.

Our utility client asked us to assist in identifying the root cause for the multiple joint failures on several two year old substation exit feeders.

Initial assessments with IMCORP’s Factory Grade® technology revealed several substandard pre-molded joints. The utility asked IMCORP to provide a dissection and root cause analysis for two joints excavated from the field.  One faulted in service prior to the assessments and the other was serviceable but showed substandard performance.

The dissection and root cause analysis produced evidence of electrical (or carbon) treeing between the inside surface of the joint and the cable insulation (the joint interface). Electrical treeing was observed at the same location in both joint samples only treeing is much more extensive in the joint that failed in service.

Electrical treeing started near the connector (where the Faraday cage makes contact with the cable insulation) and grew along the interface towards one end of the joint. (Figure 1).

Figure 1 Evidence of electrical treeing was observed on the inside surface of both the serviceable joint with substandard PD activity (left) and the faulted joint (right).

Comparisons of the manufacturer’s catalogue product size selection table and the cable diameter revealed these were the loosest fitting of three models covering this cable size range. A looser fitting joint increases the likelihood of interfacial voids and other installation errors leading to substandard performance.

Voids and stress enhancements in the presence of sufficient voltage stress gives rise to partial discharge, erosion, electrical treeing and eventually failure. Other workmanship issues identified included incorrect dimensions, contamination on the interface, and little to no evidence of void filling grease applied at the cable’s semicon cutbacks.

The utility learned the value of a Factory Grade® assessment since the substandard performance was only observable at 1.5 times the operation voltage and would have been completely missed if the assessment was only performed at operating voltage.

By partnering with IMCORP our client utility gained critical knowledge about their joint performance and soon made significant changes to their joint specification and retrained their installers.

IMCORP is the technology leader in Medium & High Voltage Power Cable Systems life cycle condition assessment and performance – IMCORP have been helping their clients achieve maximum cable reliability for more than 20 years and have assessed over 130,000 5kV to 500kV cable systems spanning in excess of 160 million feet.

THORNE & DERRICK

T&D are Specialist Distributors to UK Distribution Network Operators (DNO’s), NERS Registered Service Providers, ICP’s and HV Jointing Contractors of an extensive range of LV, MV & HV Jointing, Earthing, Substation & Electrical Eqpt – this includes 11kV/33kV/66kV cable joints, terminations and connectors for both DNO and private network applications.

Contact our UK Power Team for competitive quotations, fast delivery from stock and technical support or training on all LV-HV products.

All international sales enquiries can be serviced and supplied by our Export Power Team.

Key Product Categories: Duct Seals | Cable Cleats | Cable Glands | Electrical Safety | Arc Flash Protection | Cable Jointing Tools | Cable Pulling | Earthing | Feeder Pillars | Cable Joints LV | Joints & Terminations MV HV 

Cable Strikes Increase During Lockdown

• This article was written by Aaron Morby at Construction Enquirer

Cable Strikes

Power cable strikes have spiked since lockdown prompting the supply industry’s trade body to raise the alert in construction. Underground powerline strikes from July to September alarmingly jumped 20% to 475 incidents compared with the same time last year. The figures for Q3 are running 46% above the previous quarter (April – June 2020) total of 325.

It is not clear whether the surge has come from a rise in utility and roadworks or whether workers returning from furlough or shutdown are now neglecting basic safety procedures.

Research released today by the Energy Networks Association reveals 93% of construction workers believed they always dig safely, yet almost a third (31%) admitted to not always checking for underground electricity cables before beginning work.

Despite the threat to life, the main reasons workers did not check for underground electricity cables was because they felt it was not their responsibility (15%), or they would not dig deep enough to hit anything (24%).

Worryingly, almost one in six said if they uncovered an underground electricity cable encased in concrete, they would attempt to break them out, which could put them at immediate risk of life-threatening injuries.

To hammer the safety message home the ENA has released new emotive safety film, urging people to ‘Think Before You Dig’.

Peter Vujanic, Chair of ENA’s Public Safety Committee said: “It’s extremely concerning to hear that even though construction workers are one of the most-at-risk groups of injury involving underground electricity cables, more than one in four fail to check for cables before beginning work.

“With the proper education and support, these issues can be addressed and, ultimately, lives can be saved.”

ENA has also released life-saving safety guidelines under the slogan: Plan, Scan, Think Before You Dig.

• Plan ahead – Always be mindful of what services lie below ground when digging or excavating. Ask utility companies for plans in advance.
• Assess the risks – Identify the dangers and hazards associated with excavations and put controls in place to manage them.
• Scan and locate – Take care when digging, always locate underground cables before digging with the use of cable avoidance tools.
• First, use your hands – Before using any electric or mechanical excavation tool, you must consider hand-digging trial holes to expose the services
• Always assume –  that underground cables are live even when damaged.
• Know who to call – In case of an emergency dial 999 and tell them electricity is involved. Call 105 if you have a safety concern related to the electricity network or if you spot damage to underground cables and substations that could put you, or someone else, in danger.
• Think Before You Dig!

Further Reading

• The Hidden Risks of Breaking Ground | Protecting Against Arc Flash
• Arc Workwear Saves Lives | Watch Mitchell’s Story
• Arc Flash Risks In The Rail Industry
• Arc Flash Survivor Story – Jason Brozen

Download Your Guide To Arc Flash Here

Network Renewal With Environment-Friendly Pfisterer Cable Terminations

Pfisterer Cable Terminations

Spanish grid operator i-DE Redes Eléctricas Inteligentes, member of the Iberdrola Group, is using the advantages of the new oil and gas free retrofit cable terminations from PFISTERER for the renewal of its network infrastructure.

They allow the existing cable to be retained when ageing terminations are replaced. Easy to install, they also safeguard the environment in the long term.

Alroc Tools – Cable Jointing Tools (MV HV)

i-DE Redes Eléctricas Inteligentes, based in Bilbao, is one of Spain’s main grid operators. Like many network operators, it faces the challenge of long-term infrastructure renewal.

Networks have to be maintained, updated and brought into line with future requirements. In this case, the task was to replace ageing porcelain terminations on a 132 kV line in the Madrid metropolitan area. A modern solution was sought, but one that did not necessitate changing the existing cable.

“This is a typical requirement that we meet with our push-on EST retrofit terminations. In principle they are suitable for all XLPE cables up to a conductor cross-section of 2,500 mm². However, the solution can also be adapted for other cable types – such as here for i-DE, where an EPR cable is used.

It is compatible with substation and transmission tower installation, is easy to fit and maintain, and it is sustainable,” explains Tarek Fahmy, Senior Product Manager at PFISTERER.

PFISTERER Retrofit i-DE Spain

Environmentally safe and flexible

Whether in the substation (with or without integrated surge arrester), as a flexible solution or on the transmission tower – with its dry retrofit terminations, PFISTERER offers a comprehensive range for all requirements and voltage levels from 72.5 to 170 kV, tested in accordance with IEC 60840.

The advantage with these solid-insulated, oil and gas free terminations is that they are explosion-resistant with no risk of leakage in the event of a fault, and there is no environmental hazard at any time. Plus the terminations are maintenance-free over their entire service life.

“As well as the installation and maintenance cost savings, the environmental aspect is just as important as it allows us to sustainably renew our energy infrastructure,” says Jose Miguel Sánchez Pereira, Maintenance Manager EHV Lines Centre Region at i-DE. The PFISTERER solution meets all of the grid operator’s needs.

It has been in use since November 2020 in a substation and on a transmission tower, each with six terminations. And its flexibility is already apparent: the new terminations can be used as a self-supporting version or in existing support structures, and are also easier and faster to install thanks to their low weight.

Pfisterer

The Pfisterer corporate group has been dealing with the interfaces in the flow of electricity ever since it was founded back in 1921.

As a specialist in energy transmission and distribution, Pfisterer offer our customers and business partners a range of sophisticated, future-ready products: For all voltage ranges and wherever reliable, long-lasting systems are needed for powerful energy grids.

As well as the energy sector, they are also active in transport technology and industrial solutions.

SICON SHEARBOLT CONNECTORS

The Right Connection for All LV MV HV Conductors – For years, bolted clamps, connectors, and cable lugs have been gaining ground – with good reason. Bolted connectors offer technical and practical advantages that compression technology cannot match.

Bolt type connectors offer not only technical, but also practical advantages over compression technology. All SICON Shearbolt Cable Connectors cover a wide conductor cross-section range so that you always have the right connectors on site for any application.

Main benefits of Sicon Connectors include:

• Reliable connection for all conductors
• Optimal contact force for all conductors
• No damage to individual strands
• Installation with standard tools
• Ideal for all type of joints or terminations
• Wide application range

LV MV HV Jointing, Earthing, Substation & Electrical Eqpt

Key Product Categories: Duct Seals | Cable Cleats | Cable Glands | Electrical Safety | Arc Flash Protection | Cable Jointing Tools | Cable Pulling | Earthing | Feeder Pillars | Cable Joints LV | Joints & Terminations MV 

Subsea Power Cables in Shallow Water | DNVGL-RP-0360

This Document supersedes DNV-RP-J301, February 2014.

Thorne & Derrick can provide Joints, Terminations & Connectors for the safe and reliable operation of subsea power cable systems up to 66kV – this includes cable accessories utilising Heat Shrink, Cold Shrink and EPDM Rubber type connection and termination products from market-leading manufacturers including 3M Electrical, Pfisterer CONNEX, Nexans Euromold and NKT.

Further Reading

• Cable Grips | Supporting Inter-array, Export, Umbilical & Subsea Cable Installations
• Nexans Subsea Solutions For Power Networks
• How To Install A Subsea Cable – Power Networks
• How To Remove Bitumen From Subsea Cables & Umbilicals Using Socomore Wipes
• Avoiding Subsea Cable Failures Before They Hit The Water
• Subsea Power Cables For North Sea Link Interconnector Project

Thorne & Derrick are Specialist Distributors to the UK and international Offshore Wind & Renewable industry to provide safe and reliable LV HV Electrical Cable & Power Distribution Systems up to 66kV – we are highly customer responsive and absolutely committed to providing a world-class service.

Contact our UK Power Team for competitive quotations, fast delivery from stock and technical support or training on all LV-HV products.

Key Product Categories: Duct Seals | Cable Cleats | Cable Glands | Electrical Safety | Arc Flash Protection | Cable Jointing Tools | Cable Pulling | Earthing | Feeder Pillars | Cable Joints LV | Joints & Terminations MV HV 

See how T&D support, supply and service the Renewable Energy industry.

MV HV Cables 11kV 33kV 66kV | Cable Joints, Terminations & Connections

CLAIM FREE VOUCHERS | Arc Flash & Electrical Safety Programme

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EPSCO produced OneMoment from a Safety Manager’s perspective, with best practices that will fit in to the routines every member of your team is already doing.

OneMoment is designed with custom modules that benefit everyone at your facility, including engineers, managers, safety personnel, qualified workers, and unqualified workers too.

OneMoment covers a range of topics starting with the basics of electrical shock, hazards, and risk prevention, then moving on to advanced topics like arc flash, maintenance, and pre/post job planning.

OneMoment online electrical safety training brings EPSCO’s years of experience in the field to your team. Click to sign up today for the most comprehensive and compelling safety course out there.

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Introducing Electrical Power & Safety Company

Delivering outstanding products and services for electrical power systems. EPSCO specialize in performing Arc Flash Analysis of your facility and training your team to deal with this danger in the safest manner possible. Let us help you keep your people SAFE! Electrical Power & Safety Company is an industry leader in providing responsive, flexible, and reliable service for the industrial, construction, and mining industries. EPSCO goal is to provide each and every one of our clients with the solutions needed to efficiently and effectively manage internal power needs.

EPSCO began in 2008 as Electrical Power Solutions Inc which was a body of project managers relaying customer’s project needs to contractors versed in fulfilling their requirements. ​Today, EPSCO has expanded and provides direct onsite services, and employs a proficient and knowledgeable team of Professional Engineers, Project Managers, Field Service Technicians, and Control/Automation Specialists.  Allow the EPSCO team to provide you with the electrical power and safety solutions you need to maintain a competitive edge in a constantly evolving industrial market.