mylar busducts

Hello recivil

Mylar Biaxially-oriented polyethylene terephthalate (boPET) polyester film has several different versions, with differing melting points, electrical properties, and other major physical differences.

I do not know whether the high-rise hotels in hotter climates are using this material in busducts.

Read more here: http://en.wikipedia.org/wiki/Mylar

Kind Regards....

The problem is not in high rise towers or horizontal installations but;-

1- Mylar is a polyester film which accumulate heat inside the bars, so manufacturers using Mylar have to compensate that issue by using more bars cross section, i.e. more weight & cost.

2- Mylar is very sensitve to humidity, so give a reading ( SC ) during insualtion tests

3- Impact strength of Mylar is less than epoxy 3.5 times less

4- Using Mylar insulation create a weak point @ joints

5- Mylar can not withstand a high short circuit current compared with epoxy insulation ( sometimes 50% less )

6- Mylar get scratched after sometimes due to unbalance loads on the 3P where each bar extended depend on load %, so Mylar became stucked & smatched between bars then give short circuit and therefore Mylar products have short life time

On the other hand, epoxy insulation is a part from the bar & extend with the same % with complete elasticity & smoothly

7- All experts recomend epoxy insulation specially for Gulf environment where ambient exceed 50 Deg C. + high humidity.

8- Last, Mylar assembly is a very simple process & cheap and any workshop can assemble it but epoxy is a unique process & only professional lab can do it.

9- Famous manufacturers for epoxy insulation are;

General Electric ( Spectra ) - USA

Siemens ( Sentron ) - USA

Cuttler Hammer ( POW-R Way III ) - USA

LS - Korea

Regards

Eng. Medhat Rizk

medhatrizk2004@yahoo.com

Ducts of Mylar I have not seen.But as explained clearly in the psts it is also not used as support insulator in Bus ducts.