Restrict Possible Electrical Hazards Using Cable Ducts and Conduit Sealings in Substations

August 22, 2019

Consider an unthinkable situation. A storm has untapped its worst downpour while over an electrical substation. If not a storm, then a mains water line has cracked. Let's face it, electricity and water don't mix. With high-voltage electricity, that mix could be explosive. To address such potential disasters, trenching services have access to several highly effective ingress protection systems.

Cable Duct Installations

Left to their own devices, electrical cables end up a tangled mess. Out at a local substation, these structures distribute power, so they'd ordinarily be packed with such messes. That's why substations install wide concrete channels. These cable ducts make it easy to pull cables in without them rubbing against one another. High and medium-voltage cables organize into individual duct inlets, comms lines follow at a discrete distance, and then there's an in-place sealing mechanism, which stops water and gas ingress. Before talking any more about the seals, let's check out a line management plan.

Ducted Cable Management Systems

Cable clips separate tidily organized groups of armoured electrical lines. The wiring groups separate street power supplies and larger structure power lines. Linkages between the substation switching gear and transformer bus bars are grouped as well, then there are more clips to support the cables as they rise. Ultimately, they're there to prevent mechanical vibrations from weakening the solid and multi-stranded wires. However, even with a vibrational damage solution now in place, the powered lines and substation gear are still vulnerable.

Blocking Substation Conduits

Ironically, cable ducts function well like water carrying canals; that is not a desirable feature. If the water finds its way into a substation, a short-circuit could trigger a catastrophic blowout. Down goes the power, an entire city block or neighbourhood goes black, and it could take days to gut the damage. Until then, everyone within range of the transformer and its damaged switchgear will be stuck without power. Special sealing compounds are added to the conduits to seal the system. They use fireproof mastics and self-expanding foams, which inflate to seal the tiniest gaps. Actually, foam sealing is currently on the way out, for foamy compounds tend to break down over time.

Replacing older self-expanding foams and mastics, newer polymer-reinforced compounds are making real headway. They stop watery streamlets. The compounds also feature a fume and gas migration resistance attribute, so poisonous fumes can't travel inside or outside the structure. Of some importance, and this feature is being picked up by many cable duct designers, modular sealing systems are now being used to hold and protect cables as they enter substation ingress points. These modular fittings also help organize armoured cables, ease pulling work, and give the various sealing compounds a backing to cure against.

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