Stationary railway earthing encompasses the entire earthing system for all structural components of the rail infrastructure.
In this regard, the main objective is the protection of people within the rail environment and the safeguarding of reliable rail operations.
With DEHN, you have found a one-stop shop for all the components –
from specific railway earthing (earthing bridges, earthing connectors) to building earthing, right through to products for work safety.
Railway earthing protects people and equipment in the rail environment. It is necessary for preventing voltage being transmitted to people on the railway platforms or equipment in the event of damage; e.g. the severing of a contact wire.
Railway earthing refers to a current-resistant connection between all conductive components, the return circuit and the entire earthing at the substation. This connection must be resistant to short circuit currents, because parts of the operating current and, in the event of a fault, short circuit currents are carried along it.
A permanent connection with the return circuit (running rail or return wire) is established by earthing bridges and earthing connectors. The rail potential is also reduced as a result.
A direct connection to the return circuit is only permitted with AC traction systems, however. With DC traction systems, an indirect connection must be established using voltage-limiting devices due to the danger posed by stray currents.
Railway earthing is therefore always necessary in track systems around overhead contact lines and current collectors (i.e. areas where cables can be split or severed).
In Germany, DIN EN 50122-1 is an important standard for railway earthing concepts. Specifications from this European standard can be found in the policy "Bahn-Richtlinie RIL 997, Untergruppe 02" (German Rail Directive RIL 997, Subgroup 02), with the title "Rückstromführung, Bahnerdung und Potentialausgleich" (Return Circuits, Railway Earthing and Equipotential Bonding).
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Primarily the following components, systems and installations must be earthed:
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Railway earthing components must supply proof of short circuit withstand capability before obtaining approval from DB AG. This comes from the directive RIL 997.0205A01 "Elektrotechnische Anforderungen und Prüfbedingungen von Verbindungen" (Electrical Engineering Requirements and Test Conditions of Connections).
The test parameters are
Ik" ≤ 25 kA: Test current 25 kA, duration 100 ms
Ik" > 25 kA: Test current 40 kA, duration 100 ms
Internal, invisible connection
The earthing bridges cast in concrete are intended for earthing, return circuits and equipotential bonding. They are used for connecting internal and external earthing equipment.
A connection plate forms the interface element to the external, visible earthing system – this ensures ideal contact with the earthing connectors.
The connection to the internal, subsequently no longer visible, earthing is ensured by a copper-coated steel sheath using a defined welded connection.
External, visible earthing
Earthing connectors are bolted onto earthing bridges that are embedded in concrete. They continue the invisible, internal railway earthing. For the purpose of inspection, the bolted connection must be accessible from outside at all times after completion. Steel is the material of choice here. If nothing else to prevent damage caused by theft; something which unfortunately-happens with copper components all too often.
Good to know:
You can also find products for the earthing of large-diameter pipes – i.e. partially visible, partially invisible connections – in the DEHN portfolio for railway earthing.
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