Roxtec H3 Cable Transit Seals – How To Seal Substation Cables
Published 08 Jan 2019
uploaded by Chris Dodds - Thorne & Derrick Sales & Marketing Manager
Thorne & Derrick are distributors for Roxtec, the leading manufacturer of sealing solutions for cables and pipes, to protect electricity Transmission & Distribution assets including substations against water, gas and fire.
Roxtec H3 cable transit seals are ideal for the protection of cables and substations against constant running water entering Low, Medium & High Voltage Substations via concrete and brick foundations – the Roxtec H3 is a three-part cable transit seal that is easy to install including in wet conditions and in environments with running water; the system is suitable for normal and flood condition installation.
The cable transit withstands extreme cable bending and has a +5mm tolerance towards the aperture as well as an indicator showing when a compressed seal is achieved. The cable seal can be installed into sleeves, conduits and core drilled holes.
Partial Discharge Prevention
The Roxtec range of cable transits are resistant to constant and catastrophic water pressure and by providing firm cable retention with the cable seals forming a defence barrier against humidity and the risk of partial discharge – this ensures and maintains the optimum and uninterrupted service of substations reducing the risk of power outages.
The cable sealing system has been adopted by power utilities in the UK and overseas to seal 11kV/33kV cables – this includes both multiple single core cables in Trefoil and Triplex arrangement (BS7870) and 3 core polymeric insulated cables (XLPE & EPR including BS6622).
Below is a best practice installation guide for sealing substation cables with Roxtec H3 cable transit seals.
Installation In A Roxtec Knock-Out Sleeve
|Remove the knock-out of the sleeve before inserting the seal.||The seal can be installed from the outside of the structure.||The seal can also be installed from the inside of the structure.||The seal must always be installed in the correct end of the knock out sleeve.|
Installation In A Core-Drilled Hole
|Installation of seal into a core-drilled hole. Use a hole saw with the appropriate diameter.|
Installation In A Bolted Sleeve
For retrofit purposes an openable Roxtec sleeve can be used.
|Use the flange as template for the drilling of the bolt holes.||Attach the frame to the structure using suitable sealing method and suitable stainless fasteners.|
Installation In A Welded Sleeve
|Weld the Roxtec sleeve to the cabinet/wall|
Installation Of Cable Seals
Thorne & Derrick, working with Roxtec, can provide on-site installer training for all cable transit and sealing systems to ensure effective protection against flood damage or flammable gas migration on 132kV/66kV/33kV/11kV substations and battery rooms.
|Measure the aperture according to the table below.||Remove any dirt from the sleeve/ hole.||Pull the pipes/cables through||Cables shall go straight through the seal.|
|Make sure that the bolts of the seal are loose.||Adapt rubber layers to fit the cables.||Test with a cable. Achieve a gap of 0-1.0 mm between the rubber halves. Adapt the layers for all cables. The halves may not differ by more than one layer.||Lubricate the three parts of the seal all around.|
|Insert the seal into the sleeve. Leave a 10 mm margin to simplify the installation of the last piece.||Press all three parts of the seal into the sleeve simultaneously.||If necessary, use a rubber hammer.||Tighten the screws crosswise one turn at a time. Start with the inner screws.|
Signs Of Compressed Seal
|The seal is compressed when the rubber expands through the fittings and when the inner part bulges.||Sectional view of the seal showing when rubber expands and bulges. The required torque depends on several things, e.g cable or pipe size, amount of used lubricant, sleeve size or material in the cable sheath.|
Disassembly Of Cable Seal
|Release compression by untightening all the screws.||Use a suitable tool to remove the halves of the H3 seal. Be careful not to damage the seal.|
Reinstallation Of Cable Seal
|Make sure that the inside surfaces of the exposed packing space are free from dirt or dust.||Adapt halves, which are to hold the additional cables or pipes, by peeling off layers until you reach the gap seen in pic. 3. The number of layers may not differ by more than one between the halves.||Achieve a gap of 0-1.0 mm between the rubber halves. If not, repeat 2.||Lubricate the inside surfaces all around with Roxtec Lubricant, especially into the corners. Continue reinstallation from step 7.|
- Wait 24 hours or longer after installation before exposing the cables or pipes to strain or pressure
- Operating temperature range of cable seals is +4 to +40 °C
- Cables shall go straight through the transit seal
- Cable/pipe with considerable weight needs to be supported to prevent damage or subsidence to the seal
- Do not peel off the last rubber layer of each Roxtec module half
|Roxtec Part Number||Aperture Ø (mm)||Clearance Depth (mm)||Cable/pipe Range Ø (mm)|
|Roxtec H3 135 UG||135-140||75||0+23-43|
|Roxtec H3 150 UG||150-155||75||0+24-52|
|Roxtec H3 185 UG||185-190||75||0+48-64|
|Roxtec H3 200 UG||200-205||75||0+48-68|
Thorne & Derrick Specialist Electrical Distributor
Established since 1985, T&D distribute the most extensive range of LV, MV & HV Cable Jointing, Terminating, Pulling & Installation Equipment – contact us today for a competitive quotation.
Key Products : MV Joints & Terminations, Cable Cleats, Duct Seals, Cable Transits, Underground Cable Protection, Jointing Tools, Feeder Pillars, Cable Duct, Earthing & Lightning Protection, Electrical Safety, Cable Glands, Arc Flash Clothing Protection & Fusegear.