What is High Voltage Substation Cable Duct and Conduit Sealing?

November 15, 2016

High voltage substations accept thick copper conductors through small wall and floor openings. Covered in armored insulators, the cables pass readily through their assigned entryways, at which point they're sealed. The sealants do rapidly close cable ducts and conduits, but why exactly is this practice so important?

Protecting High Voltage Enclosures

Thousands of volts are contained and switched by voltage manipulating substations. The power is transformed by step-up and step-down equipment. Meanwhile, oil-filled housings and spring-loaded switches are managed by competent electrical engineers so that arcs are prevented from flashing. It's a dangerous setting, one full of potential hazards. External factors only serve to magnify this hazard, that is unless a cable duct and conduit sealing methodology is properly applied.

Sealing against Exterior Threats

Electricity and water don't mix, we all know that, so they should always be safely segregated. A substation that switches 11kV or 33kV power only magnifies this issue, which means a life-threatening arc could discharge if water makes its way through the point of least resistance. That, at least in this case, is the cable entryway channel. Fortunately, a top-notch sealant covers every point of ingress. As a result, the electrically-loaded structure won't be affected by the weather. Flooding is stopped. Even damp air becomes a non-issue.

Use Properly Rated Duct Sealing Kits

The selected compound must be pliable enough to apply to every cable, yet it must also cure until it forms an inviolable barrier. Initially, it will spread between the cables and into the narrowest channels, but the formulated sealant must then harden. The solid state exhibited by the cured compound is now watertight and gas proof. No amount of flooding and no gas leaks will penetrate this formidable barrier.

Properly Constrained Electrical Hazards

Previously, we've mentioned gas leaks, so let's talk about fluid retardation. In effect, cable duct and conduit sealants act as two-way blockades. Primarily, the cured barrier protects the equipment inside the enclosure from the exterior environmental factors we described, but it also protects that exterior area by stopping leaking gasses and fluids in their tracks. Basically, no fires or explosions can propagate from the confines of the substation because there's no route for the flammable stuff to take.

Transformers and switchgear line the insides of high voltage substations. When cables pass inside the sealed chamber, that seal is compromised. Cable duct and conduit sealing practices effectively close this entryway. Thanks to the newly incorporated seal, the building is safe from the external environmental threats and internal arc-propagating events that could cause a lethal shock or fire.

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