Sealing Cables
uploaded by Chris Dodds | Thorne & Derrick Sales Marketing Manager
Author | Gavin Cornall from Roxtec
Gavin Cornall (Roxtec)
Roxtec are the world leading manufacturer of cable and pipe sealing transits to protect against water ingress, gas migration and fire spread.
The following article by Gavin Cornall (Global Sub-Segment Manager T&D at Roxtec UK & Ireland) discusses cable sealing applications during running water or “flood” conditions.
Firstly, running water presents a major sealing issue for the installation of mastic type seals, curing and drying is almost impossible. This can place “stress and strain” on work programme completion times, especially approaching handover phase.
Secondly, this applies to any solution used to seal large power cables whether in a one cable, one duct format or passing in a trefoil formation through a larger duct. Such as 11kV and 33kV power power cables feeding MV substations.
The ability of the cable seal to provide reliable operation under high water pressure is essential – the flexibility of the cable seal to be installed during running water conditions is equally crucial.
Roxtec have inspected many seals where over time the cable has caused the sealant to rip or pull out of the substation wall.
Roxtec have also seen due to the weight and orientation of the cables, its almost impossible for the installer to space the cables to get sufficient coverage of compound around the cables to maintain a seal.
Roxtec Cable Transits provide effective protection to LV HV substation cables against flood damage and water penetration be it in dry or wet conditions.
In the Whitepaper we commissioned from EA Technology on Humidity Effects In Substations, I was pleased to see the emphasis on cable retention, both in normal and fault conditions.
It highlighted what I already thought, which is that without the ability to retain, the cable seal will fail over time.
The cable seal may fail on day 1 or year 1 but ultimately it will fail over time.
I would ask the following questions when evaluating cable sealing technology options from either a design, specification or installation perspective.
1) Can it be installed in “running water conditions” – if yes, look a little deeper into what that actually means.
2) Can the cable sealing solution cope with the weight and flex in operation?
When Roxtec developed the UG range, we had a very specific set of tests in mind given our understanding of these 2 issues. We developed a cable seal that was even better than our blue rubber on constant pressure. We quickly realised it could be installed on running water just like its blue cousin, the Roxtec Multidiameter cable seal module.
But most importantly, Roxtec developed specific testing for cable retention and flex.
We wanted to show Roxtec cable sealing solutions could maintain their seal, whilst the cables were pulled, bent and twisted, beyond the maximum bend radius of the cable.
All this whilst we cycled the temperature between +4ºC to +40ºC.
Needless to say it not only worked but it went beyond our expectations.
Our Roxtec H3 200 seal in fact had in excess of 3300nm put on it without failure, that’s over 336 kgs of pull out force!
So in conclusion, I would say if you only take one thing away from reading this article it is always consider: 1) Running Water Installation 2) Cable Retention Performance
LVÂ ♦ MVÂ ♦ HV
T&D distribute the most extensive range of LV, MV & HV Cable Jointing, Terminating, Pulling & Installation Equipment – we service UK and international clients working on underground cables, overhead lines, substations and electrical construction at LV, 11kV, 33kV and EHV transmission and distribution voltages.
LV – Low Voltage Cable Joints, Glands, Cleats, Lugs & Accessories (1000 Volts)
MV HV – Medium & High Voltage Cable Joints, Terminations & Connectors (11kV 33kV EHV)
Cable Laying – Underground Cable Covers, Ducting, Seals & Cable Pulling Equipment
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