Medium Voltage Cable Joint Technology Comparison - Video Set

By Chris Dodds on 3rd March, 2014

Follow us on LinkedIn

Medium Voltage Cable Joint Technology Comparison - Video Set

To support a popular discussion in T&D's LinkedIn Group, Low & High Voltage Power, Cabling, Jointing, & Hazardous Area Electricals (LV-HV), T&D have uploaded the following Videos to demontrate the practical differences across a range of medium voltage technologies.

A selection of the comments generated by this discussion have been copied below - should you wish to contribute to the discussion you are invited to Join our Open Group and start networking today with over 3,000 global power industry influencers. Invite.

Is Heat Shrinkable Cable Jointing Accessories On End Of The Technology Curve? Is It A Beginning Of Pre-Moulded For Medium Voltage Cable Jointing?

Video : MV Cable Joint : Heat Shrink Technology (SPS Shrink Polymer Systems)

Video : MV Cable Joint : Cold Shrink Technology (3M)

Video : MV Cable Joint : Cold Shrink Technology (Nexans) 

Video : MV Cable Joint : Slip-On Technology (Thomas & Betts)

Douglas Scull : Director Business Development & Technology at The Silchem Group.

I would say it depends on the premolded technology you are referring to. Premolded cable jointing technology as currently manufactured by ABB under the Elastimold brand as an example has been in existence since the early 1970's. It you are referring to the premolded technology more commonly referred to as "cold shrink" technology, then possibly you are correct, although even this jointing technology has been in existence for quite some time. At voltages up to and including 34.5kV "cold shrink" technology maybe the the preferred technology. If your reference to premolded includes stress grading materials, than that creates a whole different discussion.

Ravi Sardana : CEO Yamuna Cable Accessories Pvt. Ltd.

Hi Douglas, Thank you for your feedback. Yes, you are right both ABB/Elastimold type of Slip on or Cold Shrink (3M) type of cable jointing technologies have been around. But, they were un affordable earlier hence not considered favorably. Yes, the new range of Pre Moulded/Cold Shrink is with integrated stress grading technology. This makes the cable jointing lesser skillful and factory tested product ensures higher reliability. Cold Shrink/Pre Moulded are best for plastic/plastic cables. But, that is what is used more and more now. You find very less and old paper cables. For such joints as well there is process of converting cores into Plastic cables by using Heat Shrinkable Oil Barrier Sleeves. I  find skills for making heat shrinkable joints becoming more and more jointer driven and time consuming. Though it still remains favorite of most of the users due to its price benefits and jointers confidence.

Robert Lee : Product Manager & Salesmanager. Looking For New Opportunities.

I would say that it also depends on climate and chooice of cable type. In Sweden we have cold climate so in the winter is premolded hard to slip on and coldshrink is stiff so they shrink very slow. We also have mainly 3-core cable and you loose a lot of the advantages of premolded/coldshrink as you still need to make a heatshrink or epoxy outer jacket.

Ali Hirji : Consultant at Raychem RPG Ltd.

Ravi, having spent 44 years in the field of cable accessories, in my opinion several features can be provided in heat shrinkable cable accessories to make them less skill dependent. However even today the acceptance and use of heat shrinkable cable accessories in preference to cold shrink accessories will continue due to some very important reasons, some of which can be explained as below :
a) Cable Jointers continue to use a torch for removal of the bonded semi conductive screens.
b) The application of hot melt adhesives for creating a permanent flexible bond between cable substrates and the heat shrinkable component.
c) The unlimited shelf life offered by heat shrinkable components.
d) The growing acceptance and use of mechanical connectors which eliminate approximately 70 - 80 % cause for failure due to bad conductor connections.
e) The development of co extruded stress grading layer with the outer insulating, non tracking, erosion and weather resistant components.
f) The development of coextruded elastomeric insulating layers with heat shrinkable insulating and screened layers.
There is scope for further reducing the craft dependency of heat shrinkable products and I am sure these will be incorporated by good manufacturing companies in the near future.

Rakesh Shah : Experienced Telecom Marketing Professional.

Excellent points by Mr.Hirji, whom I never met but have always admired since my REPL days. Thanks for sharing some talking points of heat shrink cable jointing products.

 

Douglas Scull : Director, Business Development & Technology at The Silchem Group.

How about the use of dielectric silicone as a lubricant and assembly aide for premolded and cold shrink technologies. Can anyone comment on what is being used and how effective the silicone lubricants are?

 

Robert Lee : Product Manager & Salesmanager. Looking For New Opportunities.

I can only tell from user experience and from MV and that it's used in both heavy and light weight and both version as assembly aid and as a part of the electric construction. I have seen cases where wrong grease have been used with the result of burnt connectors due to failure in the stress control area.

Ali Hirji : Consultant at Raychem RPG Ltd

Douglas,
Silicone greases are used only for the application of Pre Moulded Push On Joints and Terminations. They permit easy insertion of the Push On Joint/Termination body over the XLPE Insulated Core having a bore diameter slightly in excess of the Inner Diameter of the Push On body. Cold Shrink Joints or Terminations do not require application of silicone grease since the joint/termination body is already pre expanded in the factory and is mechanically supported on a removable core. However, I have seen a Cold Shrink Termination and Joint Design which employs the use of a silicone grease as a void filling function at the semi conductive insulation screen cutback just to avoid the entrapment of air during the cold shrinking of the thick stress grading layer incorporated in the outer insulating layer. Over a period of time the silicone grease gets absorbed by the XLPE Insulation and the Silicone body leading to a void formation in the most critical area subject to the highest electrical stress.

Eric Berteloodt : Medium Voltage Product Responsable at Nexans.

Dear All,
I personnaly think a product has to be as more as possible a good compromise between :
- Cable jointers skills
- Need or not of multisizes applications
- Cost price
- Ergonomy
- Performance
...etc.....
The cable joint life is depending a lot of his water and vapor resistance. Reason why very old products are still leaving.
But I definitively feel the costumers accepting to invest time, money and able to put technical before purchasing make the good choice

Robert Lee : Product Manager & Salesmanager. Looking For New Opportunities.

Eric: I fully agree in the most of your points. As former responsible for the Euromold marketing in Sweden I would also say that tradition is a huge factor to consider. My experience is that most of the technichians out on the field in Sweden are basic trained on heat shrink joints and that's also the type of material they have first meet as it's most common. Just to show the Euromold ITK cable termination was big news to many even it have been on the market for decades. To me the big issue is still price for the cold shrink cable joint. It's still not comparable in total cost (parts+labor) with the heat shrink joint and there are not problems enough with heat shrink so not even the total cost over time is comparable.

Ravi Sardana : CEO. Yamuna Cable Accessories Pvt. Ltd.

Good inputs Eric and Robert. Surely Heat Shrinkable is far more competitive than Pre Moulded and Cold Shrink, but, if Heavy wall Heat Shrinkable with Elastomer layer and inbuilt stress control tubing is considered as mentioned by Ali Hirji, it will perhaps become as expensive as Pre Moulded. The skills and time taken is way too high in Heat Shrinkable and not to mention dependence on jointing skills. But, as you rightly pointed out most of the jointers are in practice of heat shrinkable and endorse that and also as earlier stated by Ali Hirji you cannot absolutely rule out the use of gas torch as screen on the cable is removed using gas torch and in some cases outer sleeves are still heat shrinkable. I also feel this product is very jointers driven and unless jointers are trained well on Pre Moulded or Cold Shrink applications it will continue to be a driven by heat shrinkable So we are still at the crossroads.

Sanjay Jha : Sr.Technical Manager at 3M

In my view, pre-molded cold shrink is the cable jointing technology of the near future. It is cold applied and minimizes the dependence on installer's skill to much greater extent than heat shrink products. Often these products incorporate integrated connector electrodes in the joint body, which takes out the need for filling up voids in the connector region. Also, it eliminates multiple components and has the benefit of factory electrical testing which cannot be matched by heat shrink products. In fact, cold shrink technology has even made high voltage jointing much simpler than what it used to be.

Chris Dodds : Thorne & Derrick & LV-HV Cabling, Jointing & Hazardous Area (ATEX IECEx) Electrical Group Manager

Chapter 12 of A Theoretical & Practical Guide To MV Cable Accessories covers current MV cable joint technologies - this link provides an overview of each chapter http://goo.gl/jM3ROg

  • Further reading

Essential Reading - Medium Voltage Cable Accessories Book Published By Nexans 

Invitation

Thorne & Derrick are inviting you to join LinkedIn’s fastest growing Discussion Group : Low & High Voltage Power, Cabling, Jointing, & Hazardous Area Electricals (LV-HV).

Discussion subjects include cable installations, cable jointing, electrical substation, overhead line and electrical construction at LV, 11kV, 33kV and EHV.

Network, engage and promote your profile, company or products with over 10,000 influencers.

 

linkedin-logo Click Here To Join




Category:  HV Cable Jointing & Terminating

Go back to blog index