Cable Ducts

Laying cables in HDPE ducts eliminates the need to pull cables, instead jetting can be done for installation. The main advantage of jetting is that the pushing force is evenly distributed and due to absence of any pulling forces, the friction occuring at the junctions gets minimized. Besieds, laying cables in HDPE ducts and jetting them for installation saves manpower and makes future installations easy.

VLF-HIPOT (Very Low Frequency High Potential Test) is used to determine moisture/conduction and cut/void in a given length of the cable. The test is relatively faster and requires inexpensive equipment. Following are some of the pros and cons of

VLF HIPOT

Pros:

• is a portable source with relatively low power requirement
• is a good HIPOT for conductive type defect and high impedance defects
• does not induce as much space charge as DC which lessens the aggravation of defects in aged extruded cable
• causes some defects to grow rapidly resulting in shorter test time

Cons:

• has been demonstrated to aggravate defects in aged cable without failing
• does not replicate service conditions and cannot be directly compared to factory tests
• is not recommended for aged cable with multiple defects
• does not replicate normal stress distribution in insulation with wet regions