Systems Power RVCB (Retrofit Vacuum Circuit Breaker) Switchgear
Credit: Mikolaj Kukawski | Customer Networks Manager at ESM Power Ltd
Featured Manufacturer: Systems Power
MV HV Switchgear
Mikolaj is an experienced Private HV Networks Manager with a demonstrated history of working in the utilities and medium/high voltage (MV HV) sectors of industry.
Skilled in MV HV Electrical Power Distribution Systems operation, maintenance and asset replacement. Strong operations professional with SAP experience up to 132kV for both private and DNO networks.
ESM Power design, deliver and manage LV MV HVelectrical networks safely, securely and economically – this includes ICP and DNO connections at LV, 11kV, 33kV and 132kV.
Switchgear MV HVÂ | Thorne & Derrick distribute Nexans Euromold, 3M Electrical, PFISTERER Connex, Prysmian and Shrink Polymer Systems ranges of Joints, Terminations & Connectors to enable the installation and maintenance of electrical switchgear, transformers and substations.
T&D supply Cables, Accessories & Electrical Products for Low Voltage (LV 230V to 1000V), Medium Voltage (MV 3.3kV/11kV to 33kV) and High Voltage (HV 33kV to 132kV) networks.
JOINTERS BLOG
Subscribe now to our POWER NEWSLETTER– a monthly email circulation packed with news, projects, videos, technical tips, training information, promotions, webinars, career opportunities and white papers.
Includes access to our popular JOINTERS BLOG with contributions from utility professionals, linesmen and cable jointers working on MV HV EHV cables and overhead lines typically at 11kV, 33kV, 66kV and up to 132kV.
uploaded by Chris Dodds | Sales Marketing Manager at Thorne & Derrick International
A modern generation of MV Heat Shrink Joint has been developed by Nexans for the UK utility and contracting industry – the primary application is for the jointing of 11kV BS7870 Triplex type medium voltage cables.
Independent Connection Providers (ICPs) and Power Contractors now have a credible option to ensure they obtain the most competitive 11kV jointing product prices without compromising quality.
11kv
The JTS cable jointing system now provides the most cost-competitive optionto power contractors: the cable joints manufactured by Nexans, “The Global Expert in Cables & Cable Systems” are tested in accordance to CENELEC HD629.1.
The internationally recognised quality standard ensures power system reliability and outage reductions when installed in accordance with the manufacturers instructions by Competent cable jointers.
The cable joints include high quality heat shrink tubes and components – the JTS range suits polymeric cables (XLPE & EPR), single core (up to 1600sqmm) with copper wire screens and voltage 11kV (Umax 24kV).
Outer Heat Shrink Tube
Triple Heat Shrink Tube (Stress Control | Insulation | Conductive)
Sealing & Stress Relief Mastic
Shearbolt Mechanical Connectors
Triple Wall Heat Shrink
Single Tube with Triple Function
Traditionally, heat shrink joints required several separate stages for the installation of the complete cable joint with multiple layers of heat shrink tubes needed to provide stress control, insulation and conductive functions – the labour intensive jointing procedure introduced increased risks of jointer error including tube misalignment and flamework deficiencies (scorching of tubes by overheating).
The Triple Wall design of the JTS Jointreduces installation times with corresponding labour savings.
The triple extruded heat shrink tube with integrated stress control provides compact installation with reduced components and excellent water sealing for direct burial into underground cable trench.
Mechanical connectors are included for fast jointing of conductors without resort to hydraulic crimping tools and associated die sets.
Stocked and distributed in the UK, the cable joints are now available from Thorne & Derrick with complete technical support, fast quote service and next-day delivery.
Jointer Competency Training can be booked via Thorne & Derrick and obtained from the Nexans Training Centre | Normanton | West Yorkshire WF6 1TR
The kits include clear step-by-step Jointing Instructions – Competency Certification can be issued, contact us.
Triplex Joints & Terminations
Nexans manufactured Cable Accessories are in extensive service throughout the UK DNO power grid – the Euromold brand of separable connectors are approved and are approved by several DNO/IDNO operators dependent on the product, voltage and network.
Nexans joints and terminations are increasingly preferred and adopted by NERS Accredited Independent Connection Providers (ICPs) working on 11kV private networks.
Thorne & Derrick have an International Distribution Agreement with Nexans Power Accessories UK and are their main stockists and suppliers for their range of Heat Shrink Joints & Terminations up to 33kV.
Nexans MONOi heat shrink cable terminations are a one-piece co-extruded anti-track (red) and stress control tube for connection and terminating 11kV BS7870-4-10 Triplex Cables 95-300sqmm into medium voltage electrical equipment.
Specification & Installation Instructions For Jointers
Disclaimer:This document – Jointing Instruction – is a sample instruction to be used for reference only and is for a specific cable, the relevant instruction will change as per the cable specification it is to be used on.
Thorne & Derrick
Nexans Main UK Stockist & Distributor
Contact us for Competitive Prices & Fast Delivery from Stocks for Heat Shrink, Cold Shrink & EPDM Rubber Connectors, Joints & Terminations up to 66kV.
Go to our Price List and contact us with your enquiries.
Heat Shrink Cable Accessories for 11kV Triplex Cables
Thorne & Derrick International are specialist distributors of LV, MV & HV Cable Accessories, Jointing, Substation & Electrical Equipment – servicing UK and global businesses involved in cable installations, jointing, substation, overhead line and electrical construction at LV, 11kV, 33kV, 66kV and EHV.
Thanks you Ahmed Metwally Electrical Transmission Specialist for allowing us to republish this article
Published Study for HV Cables Optimization through CIGRE-GCC 2019
Abstract
High Voltage Cables
The electric power transmission system of National Grid Saudi Arabia (a subsidiary of Saudi Electricity Company-SEC) includes a network of underground cables ranging from MV (13.8kV) to EHV (380kV) cable. The backbone of this power distribution network has a voltage rating of 110kV to 380kV with conductor cross-sectional area varying from 400sqmm to 2500sqmm.
The high voltage underground cable network has three different voltage ratings; 110kV, 115kV and 132kV. Prior to 2003, the electricity network was being operated and maintained by four individual utility companies having their own specifications and franchise areas;
132kV in the Central and Southern regions
115kV in the Eastern region
110kV in the Western region
National Grid initiated a study to standardize and optimize the designs for high voltage cables suitable for all high voltage ratings. The study started unifying the cables sizes and designs, verifying performance of existing network and analysing demand forecast.
Suitable designs and sizes were worked out and appropriate ways were looked into to optimize the design by implementing the relevant international standards and taking into consideration feedback from the maintenance and projects about existing cables.
Introduction to HV Cables
Utilities around the world are going for optimization of utilized equipment (reduce capital and operational cost). Therefore, Standards & Specifications Department of National Grid Saudi Arabia formed a team of experts to study the possibility of standardizing/unifying cable design to three sizes; 1200sqmm, 2000sqmm and 2500sqmm.
In addition, it will achieve financial savings as a result of this design optimizing.
Process flow for this study is shown below:
Study Process Flow
National Grid specifications have variety of high voltage cable conductor sizes which were based on IEC 60228 and the different operating areas requirements. However, based on ampacity required for each substation, National Grid is selecting 1200sqmm conductor size more often to cover load demands. And the other sizes 2000sqmm and 2500sqmm are the second most popular choices after 1200sqmm which can be applied for all substation requirements as shown in [Figure 1].
Reduction in Cable Layers
1. Reduction of Cable Insulation
The international standard IEC 60840 “Power cables with extruded insulation and their accessories for rated voltages above 30kV (Um = 36kV) up to 150kV (Um = 170kV) –Test methods and Requirements” does not specify the required nominal thickness of insulation for high voltage cables. But this is not the case with IEC 60502 which specify required nominal thickness of insulation for medium and low voltage cables.
However, the limitations of the insulation thickness for high voltage cables depends on nominal conductor electric stress which shall not exceed 8,0 kV/mm and the limitations of the insulation screen thickness depends on nominal insulation electric stress which shall not exceed 4,0kV/mm.
The required insulation thickness as pre National Grid specifications was 20.32 mm for 110/115kV cables and 21.6 mm for 132kV cables. These values satisfy the requirement of IEC 60840, but with high safety margins as shown in table 1 for 132kV cables.
Table 1
1200 sqmm,
132 kV cable
2000 sqmm,
132 kV cable
2500 sqmm,
132 kV cable
Insulation Thickness [mm]
21.6
The nominal Conductor electric stress [kV/mm]
4.92
4.67
4.59
< 8
The nominal Insulation electric stress [kV/mm]
2.62
2.69
2.77
< 4
Table 2shows parameters for 1200sqmm, 2000sqmm and 2500sqmm for 132kV cable and all the results are within the required range based on IEC 60840.
1200 sqmm,
132 kV cable
2000 sqmm,
132 kV cable
2500 sqmm,
132 kV cable
Insulation Thickness [mm]
18.0
The nominal Conductor electric stress [kV/mm]
5.65
5.48
5.31
< 8
The nominal Insulation electric stress [kV/mm]
3.26
3.34
3.43
< 4
2. Reduction of Semi Conductive Layers
The same principle of the cable insulation that the IEC 60840 does not specify the required nominal thickness for cable semi-conducting layers, the team made the changes in this layer based on the manufacturers experiences when it comes to operating the triple extrusion machine and trying to maintain the eccentricity of the cable.
National Grid involved thirteen (13) cable manufacturers around the world to study and check the minimum required thicknesses for semi-conduction layer which can fulfil the requirement of eccentricity based on IEC 60840 and as a result, the conductor shield and insulation shield reduced to 1.5 mm.
3. Reduction of Metallic Screen Layer
Different metallic screens are available based on National Grid specifications. Most common choice is copper wire with tape screen [Figure 2]. Its selection mainly depends on the project requirement such as radial water tightness features, electrical and mechanical properties.
However, all metallic screen types have a fundamental function to withstand the required short circuit current.
Therefore, a critical part of designing the metallic screen is to know how much an area of metallic screen can withstand the required short circuit, IEC 60949 ” Calculation of thermally permissible short-circuit current taking into account non-adiabatic heating effect” was used to calculate the required area of metallic screen of the high voltage cable that can withstand the required short circuit.
There are two ways to do short circuit calculation; using adiabatic temperature formula and using non-adiabatic factor. In this study non-adiabatic factor chosen, by using thermal constant of the media applied over either sides of the screen. Moisture impervious layers were applied to both sides.
This helped reducing area of copper wire screen from 280sqmm “as per a adiabatic calculations” to be 261sqmm “as per non-adiabatic calculation” and still fulfilled National Grid specifications to withstand 40kA for 1 second and provided good financial savings in the cost of the high voltage cable.
These reductions in the insulation thickness and metallic screen area have also increased slightly current capacity of the optimized cable comparing with the conventional cables being used in the network.
The below Table 3shows an example of the current rating values changes.
1200sqmm, 132kV cable
The load Current [A]
914
The permissible Cable current [A] – Insulation thickness of 21.6 mm – Metallic screen area of 280 sqmm
954*
The permissible Cable current [A] – Insulation thickness of 18 mm – Metallic screen area of 261 sqmm”
961*
+ 7
*Installation conditions: the standard trench of a single circuit in flat formation in a backfill duct bank at 1.45 m depth with 300 mm axial phase spacing, 40 ºC soil temperature, 2.0 ºC.m/W soil thermal resistivity (dry value), 1.2 ºC.m/W thermal backfill resistivity (dry value) and cross bonded system.”
Cable Manufacturers Production Capabilities
After the completion of the design of all layers of the cable, National Grid contacted several qualified cable manufacturers (local & international) and discussed the possibility of manufacturing cables with the suggested design and its effectiveness.
The responses received were consistent with the design provided by National Grid and its specifications were updated in 2018. Subsequently, manufacturers started production of the optimized cable size 1200sqmm which was type tested successfully.
Design of the System Test Loop
After getting the success capability from the cable manufacturer and the decision to approve the optimized design, it was type tested as per IEC 60840 in addition to a short circuit test in the presence of National Grid representatives to check the quality of the new design for the electrical and non-electrical tests, the main test loop included the following components; 50 m of cable test, two outdoor porcelain terminations, one straight joint and one cross-bonding joint based on the test loop in Figure 3.
And the additional test to ensure metallic screen/sheath withstanding required short circuit was the short circuit test for which National Grid and DNV-GL “KEMA” made a procedure & the test loop The test loop is shown in Figure 4.
Financial Cost Savings
Local manufacturers were contacted for the calculation of financial savings as a result of the cable reduction and cost index [%] for HV is shown in table 4.
Benefits from this exercise in terms of financial savings in the capital budget in the next seven years were estimated to be about 25 million US dollars.
110kV, 115kV and 132kV Cables
Description
1200sqmm, Normal Design
1200 sqmm, Optimized Design
2000/2500 sqmm, Normal Design
2000/2500sqmm, Optimized Design
Cost Index %/Km
100
93
100
95
The Results
Financial savings by reducing thickness of insulation & metal cover area “metallic shield” without affecting quality and efficiency of cables
Standardization to three sizes only; 1200/2000/2500sqmm. As a result of this optimization, cable accessories will automatically be unified/standardized for specified models of cable joints and cable terminations
Reduction in the weight of cables up to 8.6% and overall cable diameter up to 9.6%. This will facilitate the installation of cable laying thus reducing the cost of civil works
By Ahmed Metwally
Currently Electrical Transmission Specialist at Saudi Electricity Company
Job Purpose
* Approve the pre-qualification of manufacturers for electric equipment such as Cables, Cable Accessories, Link Box, SVL and Cable Cleats & Clamps.
* Authoring and updating the company specifications based on the international standards.
* Attend various type tests to verify the produced equipment is in line with requirements.
* Provide technical studies that help to use new methods in electrical transmission projects based on national and international researches.
Job Roles & Responsibilities
* Very strong experience at Extra High Voltage and High Voltage Cables and Accessories (500kV, 400kV, 380kV, 230/220kV, 132kV, 115/110kV & 69/66kV) transmission field, design, engineering, quality control and testing for substation projects.
* Attend various technical, design and progress meetings with Cables and Accessories manufacturers, SEC internal departments, and other utilities to resolve raised technical problems and to ensure smooth running of prequalification/ projects.
Achievements
* Author of the new optimized specification for high voltage cables (132/115/110kV) based on the international standard for testing and current rating calculation and induced voltage.
* Present a presentation at JICABLE2019 for the paper “Standardization and Optimization of High Voltage Cables Design.”
* Provide a technical poster at Cigre 2019 for the paper “Standardization and Optimization of High Voltage Cables Design.”
* Member of EPRI Institute – USA for EHV/HV underground cables and accessories design and installation.
Thorne & Derrick
Thorne & Derrick are national distributors of LV, MV & HV Cable Installation, Jointing, Substation & Electrical Equipment– servicing businesses involved in cabling, jointing, substation, earthing, overhead line and electrical construction at LV, 11kV, 33kV, 66kV and EHV. Supplying a complete range of power cable accessories to support the installation and maintenance of low/medium and high voltage voltage power systems:
MV HV Switchgear | Thorne & Derrick distribute Nexans Euromold, 3M Electrical, PFISTERER Connex, Prysmian and Shrink Polymer Systems ranges of Joints, Terminations & Connectors to enable the installation and maintenance of electrical switchgear, transformers and substations.
T&D supply Cables, Accessories & Electrical Products for Low Voltage (LV 230V to 1000V), Medium Voltage (MV 3.3kV/11kV to 33kV) and High Voltage (HV 33kV to 132kV) networks.
JOINTERS BLOG
Subscribe now to our POWER NEWSLETTER– a monthly email circulation packed with news, projects, videos, technical tips, training information, promotions, webinars, career opportunities and white papers.
Includes access to our popular JOINTERS BLOG with contributions from utility professionals, linesmen and cable jointers working on MV HV EHV cables and overhead lines typically at 11kV, 33kV, 66kV and up to 132kV.
Thorne & Derrick are working with Coex Training (RTO# 41119) in Australia to promote their Hazardous Area & High Voltage Switching Training Courses.
WHAT TO EXPECT AT COEX HIGH VOLTAGE Switching COURSEs
Coex Training’s High Voltage Courses cover everything from basic electrical theory all the way through to physically conducting an HV switching program in our training substation.
While some of the basic electrical theories discussed in the course may already be familiar to some, it is a great way for those that have spent some years out of their apprenticeship to refresh their memory. Coex also goes through applicable electrical standards and legislation for high voltage activities, addressing areas such as competency requirements for HV Operators and explaining why you can’t start switching with a certificate alone.
Coex trains students on the importance of gaining permission from the network entity that owns the installation, as well as the individual responsibilities a High Voltage Switching Operator and Electrician has. We fully explain the duty of care of your employer and your duty of care as an employee.
High Voltage Switching Questions Answered
The courses will assist students in their understanding of a variety of electrical equipment fault ratings and the equipment’s capabilities. These learnings are crucial in helping you truly understand the limitations on what your equipment can and can’t do. Some questions that will be answered in the course are as follows:
Where does the fault current come from?
What do the numbers on the nameplates of the equipment actually mean? (With regards to fault rating, heat rating and mechanical stress rating of the equipment)
What is the most effective way of using my PPE equipment?
What are the limitations of PPE?
PPE is your last line of defence when equipment protection systems fail. The highest rating PPE we typically use in Australia for the distribution HVÂ Switching is an incident energy level of approx. 40 calories per square centimetre. Anything above that level can be manufactured to protect you from the heat but not the percussion wave.
It is limitations like these that are extremely important to fully comprehend and understand, so as not to put yourself or others in danger. This is another reason why the Coex High Voltage course is so necessary.
Additional skills learned in the courses are to do with administration procedures, in particular, the writing and understanding of permits.
Frequently asked questions include:
How is a permit put together?
What permits are out there?
When should you use an access permit?
When should you use a vicinity permit?
What does a ‘powerline corridor permit’ actually entail?
How do we accurately test permits?
It is important to understand how permits work so that you are not breaking any laws or isolation practices when switching, and more importantly, keeping everyone working under the HV isolation safe.
A good way of keeping yourself in check when dealing with permits and correct procedures is also having good knowledge and understanding of Switching Programs. You will be instructed on how to create and write accurate switching programs, giving you the skills to put one together in a way that ensures you and the people you’re isolating for are kept safe.
Once you have practised writing up different programs for different switching scenarios and network configurations in the course, you will then be given the opportunity to practically apply that knowledge by carrying it out in our safe and controlled substation.
Coex Training is an Australian based Registered Training Organisation. They offer Nationally Recognised Qualifications and non-accredited courses specifically designed to give students the competencies required to excel in their careers.
With a long history of providing training services to industries such as Resource, Infrastructure, Defence, Manufacturing and Construction, they pride themselves on their dynamic and student-focused courses which have been developed to meet the high expectations of students, employers and industry. Coex training have an extensive portfolio and can provide training across all levels: from general awareness through to Certificate and Diploma level qualifications. Their national scope enables them to tailor their programs to meet the varied needs of organisations and students located across Australia and the globe.
Coex High Voltage Switching Courses
JOINTERS BLOG
Subscribe now to our POWER NEWSLETTER– a monthly email circulation packed with news, projects, videos, technical tips, training information, promotions, webinars, career opportunities and white papers.
Includes access to our popular JOINTERS BLOG with contributions from utility professionals, linesmen and cable jointers working on MV HV EHV cables and overhead lines typically at 11kV, 33kV, 66kV and up to 132kV.
15,000+ Subscribers. ➡Â
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.
medium/high voltage (MV HV) sectors of industry.
Thanks you Ahmed Metwally Electrical Transmission Specialist for allowing us to republish this article 
