Cable Joints & Terminations HV

Heat Shrink Terminations | Tracking on Medium Voltage Cable Terminations

By Stephen Harrison | Training & Technical Manager Current Training Service Pty Ltd

Terminations for MV Power Cables

The image shows a shed (rain shed) – this is a heat shrink moulded part and component of standard medium voltage cable terminations. The installed rain shed is in operation on a 33kV indoor installation – tracking and discharging can be seen on the outside of the shed (rain shed) element of the cable termination and if left unchecked this will eventually cause the MV cable to fail in the field. At 33kV (Um 36kV) this cable termination was suffering a tough time whilst in service and it was eventually pulled out of operation after the discharge was identified. The discharge and tracking can be seen between the surface of the anti-tracking tube and the shed (rain shed) collar which is due to poor installation by the cable jointer. Sheds (rain sheds) must be shrunk down with collar connecting to the anti-tracking tubes evenly. If in doubt how and where the shed (rain shed) is to be installed, refer to manufacturer’s instructions.

Thorne & Derrick | Distributors of Medium Voltage Joints, Terminations & Connectors

3M Electrical | Nexans Euromold | Pfisterer CONNEX | Main UK Stockists

Flooding & Underground Cables: Myth or Reality?

Protecting Underground Cables

This Article was originally published by T&D World.

From Superstorm Sandy to Hurricanes Harvey, Irma, Maria, Florence and Michael – the volume of rain and storm surge has and can cause unprecedented flooding.

Flooding negatively impacts power systems – but not for the reasons you might think. Power Delivery Intelligence Initiative (PDi²) is taking on the myth that flooding compromises underground cables.

Medium and high voltage cables are designed to be direct buried, often in areas where they will be below the water table and permanently in a wet environment. Under normal weather conditions, manholes and vaults are often full of water and need to be pumped out for even routine inspections.

Outer jackets for these cables, made of polymeric materials, resist moisture permeation to prevent water incursion into the cable over the life of the system.

Roxtec Cable Transits provide effective protection to LV HV substation cables against flood damage and water penetration be it in dry or wet conditions.

In the rare instances that water permeates a cable jacket, certain insulations, including tree-retardant crosslinked polyethylene, are designed to resist growth of water trees that could cause premature cable failure. In addition, cable also can be manufactured using moisture-blocked conductor, water-swellable tapes and powders and corrugated sheath to make them more moisture impervious.

Underground cables are expected to meet rigorous standards specifically addressing operation under adverse weather conditions like flooding. These standards take into consideration both moisture and chemical resistance as there can be significant differences between rain and flood water. ICEA, ANSI and AEIC require adherence to a variety of test procedures that address moisture barriers, water-blocking components, water-resistance tests and other sealing components and technologies.

CSD RISE Duct Seals – combining ease of installation with cable duct sealing and protection against water, gas and fire.

Cables are rarely at fault for failures related to flooding.

The biggest concern for flooded underground systems are the open-air terminations at ground level where external or internal contamination has occurred due to poor sealing. However, technology is improving here as well.

Certain elbow and T-bodies are typically submersible and have not shown any significant negative impact after flooding. Joints and other accessories like link boxes are used in manholes and vaults and can be designed and installed in such a way that they can operate submerged in water without compromising cable insulation integrity.

Areas known for periodic flooding can take additional measures for outer protection of cable joints like metal housings moulded with epoxy coatings or fibreglass boxes filled with water sealants.

These designs are typically electrically screened with electrical fields that are fully contained within the solid insulation of the cable.

Myth – flooding and underground cables

busted.

Cables are made to resist water under both normal and extreme operating conditions. As long as water does not extend to the exposed terminations, there is little risk of failure due to flooding.

Where terminations are at ground level, technology and products exist to mitigate the chance of failure. These solutions should be part of storm hardening efforts and decisions regarding choices for new and rehabilitated power infrastructure.

Joint | Terminate | Connect Medium & High Voltage Cables MV HV

Further Reading

• Sealing Underground Cables & Pipes Under Constant Water Pressure
• Submersible Switch Applications By G&W Electric
• 21st Century Costs of Underground Distribution

LV, MV & HV Jointing, Earthing, Substation & Electrical Eqpt

Thorne & Derrick International are specialist distributors of LV, MV & HV Cable Installation, Jointing, Duct Sealing, Substation & Electrical Equipment – servicing UK and global businesses involved in cable installations, cable jointing, substation, overhead line and electrical construction at LV, 11kV, 33kV and EHV.

THORNE & DERRICK 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 

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 

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