Cable Joints & Terminations HV
33kV Shunt Reactor | A TRV Study for a UK Offshore Windfarm
August 18th, 2020
33kV Shunt Reactor
A TRV Study for a UK Offshore Windfarm
Enspec Power have released a case study of a TRV assessment for a UK Wind Farm.
This assessment was done to ensure the 33kV Circuit Breaker was sufficiently rated for the sites 2.5MVAr shunt reactor.
Enepec Power carried out full modelling of the medium voltage network, site and shunt reactor to investigate the peak TRV and RRRV values and compared these against the breaker ratings.
The full case study can be found via download. The full redacted paper is available on request from Thorne & Derrick.
This report was produced by Enspec Power Ltd – it details a Temporary Recovery Voltage (TRV) study carried out for ABC Wind Farm in order to assess TRV ratings of the shunt reactor circuit breaker.
The following events have been investigated: De-energisations of the shunt reactor, credible single phase-to-ground and three phase-to-ground faults, simulations of the worst case TRV peak and Rate of Rise Recovery Voltage (RRRV) values of the vacuum circuit breaker (VCB), with a comparison of the results with the switching capability of the VCB according to IEC 62271-100, and finally a discussion of the possible solutions in order to reduce the TRV to below VCB ratings.
In conclusion, the investigations found that the TRV values for the de-energisation of the shunt reactor and the fault interruption of a three phase-to-ground and single phase-to ground fault at the reactor terminals were not compliant with the corresponding envelopes described in IEC 62271-100 (T10 / T60).
The probability of a fault between the VCB and shunt reactor terminal is low. Nevertheless, the de-energisation of the shunt reactor would be considered as frequent. Thus, a TRV / Overvoltage suppression / mitigation method should be considered. It is essential not only for the TRV requirement, but also for protecting the reactor against over voltages.
An RC snubber with appropriately sized SAs, or controlled switching with appropriately sized SAs are considered to be the best solutions to suppress the TRV to below the breaker ratings, minimise/eliminate probability of reignition phenomena and reduce the overvoltage stress at the reactor terminals. Note that independent pole operation is required for the solution of controlled switching.
About Enspec Power
Enspec Power help organisations to make money and to save money – professional engineers can do this! They’ve been making businesses more profitable since 1998 when their sibling founders, fed up with the bureaucracy of larger organisations, decided to go it alone and set up Enspec as a friendly, flexible engineering company.
Two decades on, they’re still a friendly bunch and one of the UK’s leading independent specialists in power quality engineering. They really understand electrical power systems and are passionate about what we do and what’s happening in the wider world of technology.
They are progressive members of The Institution of Engineering and Technology (IET) with links to academia – so if they don’t have the immediate answers, chances are they know somebody that does. They offer specialist engineered products and services such as Power System Studies, Power Factor Correction, Harmonic Filters, Reactive Compensation, Point-on-Wave Switching and Site Services. They’re here to help all manner of heavy electricity users such as utilities and renewables, oil and gas, manufacturing and other industries.
Company News
Specialist Suppliers of High Voltage Electrical Equipment & Cable Accessories
Jointing, Earthing, Substation Electrical & Safety Equipment Distributors
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
Distributors for 3M Cold Shrink & Scotchcast | Nexans Euromold | Pfisterer Connex
How to Protect HV Underground Cables
August 18th, 2020
Republished with the Kind Permission of Sam Soady |
Eccentricity Pty Ltd Director /HV Operator / Cable Jointer
How to Protect HV Underground Cables
Underground high voltage cables have been a great innovation to the electrical distribution industry. While they make an installation look more visually pleasing than the overhead conductor systems currently being utilised, they are often exposed to scenarios which are overlooked by electrical designers and engineers.
It is common practice to protect your cables from mechanical damage via installation methods and manufacturing mechanical protection systems, however in some areas, cables have an environmental issue leading to a shortened lifespan and failure. Termites!
Even though electrical cables are not considered food for the termites it is well known they can attack underground cables damaging the integrity of the installation, which eventually leads to failures.
Some areas in Australia have a higher risk of termites such as the northern part of Queensland and the Northern Territory requiring underground cables to have an added protective layer during manufacturing.
Methods for termite protection on underground systems include hard physical barriers such as:
- Rigid HD PVC conduit systems.
- Added layer of plastic Nnlon sheath (must maintain a smooth surface).
- Metal barriers such as brass, copper or steel tapes.
- Chemical infused High Density Polyethylene with Cypermethrin.
While all systems are highly effective at providing termite protection, the most common method utilized for modern installations is option 4 – chemical infused High Density Polyethylene.
This solution provides the most cost-effective choice as additional layers are not required to be added to the normal specification/design of the cable. Some companies however have moved away from this method due to Health and Safety concerns which have arisen from the use of these chemicals.
When performing joints/terminations on the cable, it is imperative to continue the termite protection all the way through the cable joint. This is generally achieved using stainless steel mesh being installed as a protective layer over the joined cable (refer image). The use of roll springs or hose clamps ensures termites cannot enter the joint body.
About Eccentricity
Eccentricity is a specialised Brisbane based company with a team of dual trade electricians and cable jointers. Our technicians are fully qualified to work on cables up to 66kV, including XLPE, PILC and EPR cables, backed by over a decade of industry experience.
With a modern and fully compliant fleet of industry vehicles, we are capable of accessing any high risk environment to perform works with a wide range of major MV HV cable jointing projects including, mining, oil, gas, renewable energy, and high voltage transmission networks.
Eccentricity has the capacity for small or large scale projects, providing reliability of power networks wherein client satisfaction is a top priority. We provide a high level of quality with all aspects of both installation and commissioning, ensuring we comply with all relevant regulations and legislative provisions.
Specialist Suppliers of High Voltage Electrical Equipment & Cable Accessories
Jointing, Earthing, Substation Electrical & Safety Equipment Distributors
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
Distributors for 3M Cold Shrink & Scotchcast | Nexans Euromold | Pfisterer Connex
Cable Damage | PFISTERER Universal Repair Kit
August 17th, 2020
Pfisterer Universal Repair Kit
For All Types Of MV HV Cable Damage
One wrong move with an excavator shovel and the cable is cut. Hundreds of households and businesses are left in the dark. When cable damage occurs, the cable has to be replaced quickly.
With the PFISTERER Universal Repair Kit, they offer grid operators the first “ready-to-use” cable repair system – suitable for all XLPE insulated cables, regardless of type, age or diameter. Energy suppliers can repair MV HV cable faults within a very short time, even in historically evolved networks.
Fault-free grid operation is a must for energy suppliers, not only with a view to customer satisfaction but also because of high downtime costs.
Nevertheless, damage to conductors caused by construction work, ageing or water ingress cannot be completely prevented. When damage occurs, the cable has to be replaced quickly. Yet with historically evolved networks, preventive inventory holding is extremely cost-intensive due to the large number of installed cable types and conductor diameters.
Replace – Plug In – Finished
This is where the PFISTERER Universal Repair Kit comes in, enabling selective and fast repairs to damaged sections of installed cables. It features the universal plug-in principle of PFISTERER fittings. These enable all kinds, materials and diameters of different cables to be connected.
In combination with just one defined XLPE replacement cable – for example the cable with the largest cross-section in the operator’s grid – universal and reliable repair kits for faulty cable sections can be put together within a very short time, regardless of which XLPE cable type and cross-section has been affected by the damage. Thanks to the connection fittings, the pluggable replacement part fits all XLPE cable types in the network.
Less Stock, Less Outlay
As a result, grid operators cut out the expense of holding a stock of all cable types. At the same time, the modular design of the joints and connectors reduces the range of parts that need to be stocked.
The universal cast resin joint is suitable for voltage levels up to 170 kV. It also meets all necessary shielding requirements including cross-bonding or for fibre optic cable monitoring. And it means simpler installation for the fitters, as only one universal system needs to be used.
Ready-To-Use: Quick Deploy Solutions
The PFISTERER fittings are oil and gas-free and therefore ready to use immediately. The new Universal Repair Kit is part of a whole series of rapidly deployable solutions – the Quick Deploy Solutions – which PFISTERER provides to assist its customers with repair, installation, maintenance or overhaul activities.
These include connection solutions for easily transportable emergency transformers, as well as interim cable systems and a universal kit for bridging system components in substations.
Stockists & Suppliers
The range of Pfisterer cable plugs, joints, terminations fittings and accessories offers solutions for virtually all MV & HV Cable Connection applications – Pfisterer accessories use silicone as an insulating medium due to the excellent properties that it possesses.
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 cable systems:
- Slip-on Cable Terminations
- Cold-shrink Cable Terminations
- Heat-shrink Cable Terminations
- Cable Joints – Heat & Cold-shrink
- Separable Connectors (Euromold)
- Surge Arresters & Switchgear/Transformer Bushings
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
Cross Bonded Joints on MV Cable Circuits
August 17th, 2020
Cross Bonded Joints on MV Circuits
Republished with the Kind Permission of Sam Soady |
Eccentricity Pty Ltd Director /HV Operator / Cable Jointer
Cross Bonded Joints on MV Circuits
When dealing with medium voltage (MV) cables it is important to consider whether to include cross bonding joints in an installation. Cross bonding joints cause a reduction in the induced currents circulating on the metallic screen of a MV cable.
Cross bonded grounding schemes are generally used in high voltage (HV) cable systems above 72.5kV voltage class while MV cable systems are usually solidly grounded without interchanging the cables screens of the different phases.
A solidly grounded system requires the metallic screen to be directly connected to ground potential at both extremities of the circuit, ie each end of the cable. The solidly grounded circuits, especially on longer runs and under high energy outputs become subjected to these circulating currents which diminishes the performance of the installation.
High circulating currents on the metallic screen of the cable can have negative consequences on cables and their accessories.
Cables become subject to high energy losses, overheating and reduced current carrying capacity, and overloading / damaging of the grounding connections of cable terminations and screen connections in cable joints.
Cross bonding schemes can be used to mitigate the effects of induced circulating currents, by establishing an insulated interruption between the joint screen wires as detailed above.
If the screen is solidly bonded to earth on both ends of the cable, a closed electrical circuit is built through the ground that allows induced AC current to flow continuously.
Other methods to reduce this circulating current include construction of the cable (3 core or single core), laying a trefoil arrangement, and running the cable at reduced load capacity. While these methods will not balance the circulating currents to zero, they can minimize them to an acceptable level.
Cross bonding joints can be particularly useful in renewable energy farms, where the MV cables are under high loading capacity and can run over 10km in one circuit.
This would allow for cables to be run to near full load capacity without diminishing the lifespan of the cable and its accessories. This provides a much more cost effective and safer solution compared to designing these installations with a solid grounded system.
Eccentricity provide a full assessment of your installation by use of thermography and electrical testing methods to determine the condition of your MV cables. They can retrofit cross bonded joints into your electrical installation where excess circulating currents are present increasing the lifespan of your cabling and accessories.
About Eccentricity
Eccentricity is a specialised Brisbane based company with a team of dual trade electricians and cable jointers. Our technicians are fully qualified to work on cables up to 66kV, including XLPE, PILC and EPR cables, backed by over a decade of industry experience.
With a modern and fully compliant fleet of industry vehicles, we are capable of accessing any high risk environment to perform works with a wide range of major MV HV cable jointing projects including, mining, oil, gas, renewable energy, and high voltage transmission networks.
Eccentricity has the capacity for small or large scale projects, providing reliability of power networks wherein client satisfaction is a top priority. We provide a high level of quality with all aspects of both installation and commissioning, ensuring we comply with all relevant regulations and legislative provisions.
Specialist Suppliers of High Voltage Electrical Equipment & Cable Accessories
Jointing, Earthing, Substation Electrical & Safety Equipment Distributors
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
Distributors for 3M Cold Shrink & Scotchcast | Nexans Euromold | Pfisterer Connex
Intellix BMT 330 | HV Bushing Monitoring & Partial Discharge Detection for Substation
August 11th, 2020
HV Bushing Monitoring & Partial Discharge Detection for Substation | Intellix BMT 330
Intellix BMT 330
HV Bushing Monitoring & Partial Discharge Detection for Substation
Bushings account for a large proportion of High Voltage (HV) substation failures, often causing severe and costly damages. The Intellix BMT 330 is a HV bushing monitoring and partial discharge detection equipment to be used on substations detecting failures and issues efficiently and effectively.
Preventive maintenance, early replacement and regular offline testing has been employed to address this issue in the past. Now, technology exists that enables asset owners to detect impending failures and reduce their maintenance costs.
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The Intellix BMT 330 is an online system that continuously monitors the condition of the bushings in real-time and can also detect developing Partial Discharge (PD) activity in the transformer main tank. It will alert personnel of fault conditions at an early stage and provide vital health information on the bushings and the transformer.
Furthermore, it provides end users with the information they are used to receiving from offline tests, namely changes in capacitance and power factor, to assess the bushing dielectric efficiency and insulation integrity.
Intellix BMT 330
Intellix BMT 330
Features & Benefits
- Comprehensive monitoring of transformer bushings and PD activity on a 3-phase transformer or a bank of 3 single phase transformers
- One product combining online continuous bushing monitoring and partial discharge activity in the transformer main tank using the same bushing adaptor
- One diagnostic software, GE’s Perception, used for bushing information, PD activity and DGA data analysis, resulting in familiar easy-to-use information
- One supplier installing, servicing, ensuring proper communication and minimizing administrative burden in order to lower the total cost of ownership of your transformer
INTELLIX BMT 330
Applications
Power Utilities
- Enables condition-based maintenance of transformer bushings
- Designed for various three phase configurations
Metals
- Monitors bushing conditions to avoid unplanned production stoppage
- Monitors PD in over-stressed assets in aluminium or steel mills
Petrochemical
- Detects arcing faults with transformers
- Monitors bushing health to avoid catastrophic failures of transformers
NEWS | GE announces a new addition to its comprehensive portfolio of transformer monitoring & diagnostics solutions. The Intellix BMT 330 Bushing Monitoring & Partial Discharge detection system is an on-line system that continuously monitors the condition of transformer bushings and detects developing partial discharge (PD) activity in the transformer main tank on single phase or three phase substation transformers in utility and industrial applications. Bushings account for a large portion of transformer failures, often causing severe and costly damage. With this comprehensive active monitoring system, asset owners and operators are alerted to potential issues before they become critical failures – reducing equipment losses and costs associated with maintenance, asset replacement and system downtime.
The Intellix BMT 330 can be utilized as a standalone system or as an integrated solution with GE’s Kelman™ TRANSFIX Dissolved Gas Analysis (DGA) mutigas analyzer, Multilin 845 Transformer Protection System and Perception™ Fleet Management software to provide comprehensive situational awareness and visualization of the transformer’s condition and root cause of transformer failures.
THORNE & DERRICK are national distributors of LV, MV & HV Cable Installation, Jointing, Duct Sealing, Substation & Electrical Equipment – we service UK and global businesses involved in cable installations, cable jointing, substation earthing, overhead line and electrical construction at LV, 11kV, 33kV and EHV.
Since 1985, T&D have established an international reputation based on SERVICE | INTEGRITY | TRUST.
Contact us for 3M Electrical, ABB, Alroc, AN Wallis, CATU Electrical, Cembre, Centriforce, CMP, CSD, Elastimold, Ellis Patents, Emtelle, Euromold, Filoform , Furse, Lucy Electric & Zodion, Nexans, Pfisterer, Polypipe, Prysmian, Roxtec, Sicame, WT Henley.
