The HGS100RW all-purpose voltage limiter is a piece of protective electro-technical equipment that has a conductive connection to a tower providing tractive support (OLE) and to the rail via a 10mm conductor. Since rails are insulated, devices are used that only allow through voltages higher than:
- 250 V – places accessible to the public (HGS100RW 250V)
- 500 V – places not accessible to the public (HGS100RW 500V)
The voltage limiter is used in areas where dangerous contact voltages could occur. In these areas all conductive equipment – such as TV towers, bridges, fences, gutters, etc. and excluding conductive structures that are small or that do not contain or support electric equipment – must be fitted with such equipment.
Situation without HGS100RW installed
- A passing train causes isolator failure which leads to a danger of potential difference
- HGS100RW is NOT installed, which means there is no conductive path between the overloaded area and the substation
- The current starts to flow, causing difference of potentials
- The safety switch does not trip: human lives and equipment are endangered
❌Human lives ENDANGERED
❌Equipment NOT PROTECTED
Situation with HGS100RW installed
- A passing train causes isolator failure which leads to a danger of potential difference
- HGS100RW IS installed and generates a conductive path between the overloaded area and the substation
- The increased current loads are sensed at the substation, which trips the safety switch: all personnel and equipment are protected
✔️Human lives SAFE
✔️Equipment PROTECTED

Reference List of Applications
HGS100RW
- Railway electrification no. 293 Sumperk-Kouty nad Destnou (Czech Republic)
- College reconstruction no. 293 Brno-Kralovo Pole-Kurim (Czech Republic)
- Railway optimisation Bystrice nad Olsi-Cesky Tesin, part 2, rst. Cesky Tesin (Czech Republic)
- ZSR, Railway modernising Puchov Zilina, at speed under 160 km/h, II. Phase (Slovakia)
HL120
- Public transport system of Bratislava (Slovakia)
- Public transport system of Košice (Slovakia)
Corresponding Standards
IEC 61643-11: Low-voltage surge-protective devices
Part 11: Surge-protective devices connected to low-voltage power systems – requirements and test methods
IEC 60721-2-1: Classification of environmental conditions
Part 2: Environmental conditions appearing in nature – temperature and humidity
EN 50125-2: Railway applications. Environmental conditions for equipment-fixed electrical installations
EN 50125-3: Railway applications. Environmental conditions for equipment. Equipment for signalling and telecommunications
EN 50122-1: Railway applications. Fixed installations. Electrical safety, earthing and the return circuit
EN 50110-1: Operation of electrical installations. General requirements
IEC 60913: Railway applications. Fixed installations. Electric traction, overhead contact lines
IEC 62128-1: Railway applications. Fixed installations. Electrical safety, earthing and the return circuit
Part 1: Protective provisions against electric shock

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HAKEL spol. s r.o. was founded in Hradec Králové – hence the name HrAdec Králové ELektro – on 18 October 1994.
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