HV Cable Termination-Heat shrink vs cold shrink

[Arevaengineer]

Hi

Can anybody point out any article on this subject. I have come to learn that Heat shrink cable termination is no longer recommended in Medium voltage switchgear(1000V to 52kV).Instead cold-shrink termination is recommended.
The reason being when heat shrink termination is applied, over the years it becomes sensitive to moisture and emits a chemical reaction which is harmful for the switchgear.

Thanks for your inputs.

 

[benlanz]

I have not heard of such a statement. I would be glad to learn but, this does not sound well founded.

Both HS and CS terminations perform very well... if they are installed properly!! Both are highly qualified for many installation scenarios. HS terminations have a longer history of use and are generally seen to more mechanically durable. CS terminations are easier to apply. HS require more skill to install -heat the material enough... but not too much - that's a tough one from some technicians. I hope this helps.


Benjamin Lanz
Vice Chair of IEEE 400
Sr. Application Engineer
IMCORP- Power Cable Reliability Consultants

 

[Arevaengineer]

Dear Mr.Lanz

Thankyou for your valuable comment.

Regards

 

[TMD]

Arevaengineer: I'd like to know the source of your information. We've used HS terminations exclusively and have had our work PD tested to ensure a good termination. And it was fussy work. We're a bit skeptical about changing horses, but do see the advantage of cold shrink.....

 

[stu1]

We have applied lots of heat shrink termination and splice kits. We also have been experimenting with cold shrink splices for 11Kv cables. We find heat shrink durable and performs well in switchgear, transformers and motors. We found cold shrink did not provide much mechanical protection to our armoured cables . The advantages for us was the lack of naked flame or heat gun permit to work problems. Please post your findings.

 

[neps3]

Just to add a few things.

HS has its long standing history of good use in the industry. The advantage of CS is that on HV motors (ie. 6.6kV) which requires testing every year or periodically, CS has its economical advantage 'cos it can be reused.

 

[benlanz]

I checked with the top engineers at Tyco/Raychem and their competitor 3M during the latest IEEE/ICC meeting. Neither has heard of the problem described by Arevaengineer and said that the point is technically unfounded. The only know problem with heat shrink terminations is if they are used in an area where they come in contact with a certain kind of silicone based paint over spray. Even in this case, the terminations take a long time to deteriorate and do not affect the reliability of the switchgear.



Benjamin Lanz
Vice Chair of IEEE 400
Sr. Application Engineer
IMCORP- Power Cable Reliability Consultants

 

[Dumbo2929]

Here's my two cents, from being a utility engineer in charge of a number of cable splicing crews. The reason for the shift to cold-shrink is safety with the torch. If you can eliminate one potentially damgereous thing, why not do it. This is very true in underground distrbution, where cable splicers work in confined spaces, that sometimes have gases such as methane in them. Raychem and others still make and promote the heat shrink splice, as it is a time-proven product. The cold shrink is gaining popularity for the safety reasons. It is truely user preference. Using the torch in the back of some swicthgear cubicles might be tight and could damage paint, barriers, etc.

 

[CKent]

I've done technical evaluations comparing HS, CS and slip-on type pre-molded splices and terminations. Based on technical articles, I'd say HS is probably, still, the most reliable type amongst them all...Our utility have had favorable experience with HS terminations but is now using mostly CS terminations (at 35 kV) primarily because of its ease in installation and constantly maturing technology of CS terminations/splices. Price of CS (at least for termination) is also becoming competitive with HS. Add to this the safety it brings particularly in working inside manholes, where gases could be present. In splices, we are using all the three types mentioned. What keeps us from adapting completely the CS splices is its current price, which could be as high as 4x that of the slip-on type and about 1.5x-2x that of the HS type. Based on my benchmarking with other utilities in the US, a lot are still using the slip-on type splices primarily due to the same reason...and since the slip-on type fairly gives a good performance, it seems hard to justify complete transfer to CS...

Nevertheless, CS boast of unrivaled ease in installation and excellent reliability comparable to HS...but as pointed out by benlanz, proper installation (including preparation) plays a similar important role in the overall performance of termination and splices.

 

[benlanz]

You may already know but, for your information, both Raychem and 3M can supply cold shrink accessories.

Regards,

Benjamin Lanz
Vice Chair of IEEE 400
Sr. Application Engineer
IMCORP- Power Cable Reliability Consultants

 

[CKent]

Yes we know that already benlanz...I didn't want to go into the details of my comparison...however, if you ask me, the CS from 3M is still much easier to install and I'd say minimizes more of the installation error due to proper positioning of the stress relieving portion to the conductor splice area...and virtually no force is required to fit since you only need to pull the special cord...this feature of 'shrinking' is, to me, better than that used by Raychem, which utilizes a 'whole, two-piece cylinder shaped plastic' to expand the splice to its pre-installed state...force is needed to remove this plastic and shrink the splice to the cable.

 

[Electic]

I have never heard of a Heat Shrink termination causing harm to switchgear and would also like to know more about that.

One more reason to sometimes consider a cold shrink in typical industrial applications: when multiple cables are landed in parallel on a compact pad, it is difficult to uniformly apply the heat all the way around each to make a satisfactory Heat Shrink terminations.