Page 8 - dehn-protects-the-railway-infrastructure

Protection of direct current railway systems Selection guide: Protection of direct current railway systems
(tram, urban railway, underground railway)

The constant growth of urban centres worldwide necessi- Similarly, in the event of certain faults like, e.g., when an Application Type Part No.
tates further expansion of local public transport. Direct overhead contact line breaks, impermissibly high touch
current urban and underground railway systems are be- voltage may occur and directly endangering people. So- Protection of the power supply
coming more important and being extended. Different DC called voltage-limiting devices are installed to prevent Mains 600 V DC + 750 V DC DEHNtrack DTR 1.2 10 3 990 301
voltages from 220 to 3000 V require special protective cir- the occurrence of dangerous overvoltages between the in- Mains 1500 V DC DTR 2.4 10 3 990 302
Mains 3000 V DC
DTR 4.8 10 3
990 304
cuits. A specific characteristic in direct current railway sys- sulated tracks of electric railways and the earthed system
tems is the insulated track installation. Prior planning of parts. EN 20122 also refers to the application of these de-
the earthing and the clever application of selected earthing vices for so-called “open traction system earthing”. Their
components can defuse potential problems, like adverse job is to permanently connect system parts in the overhead
stray current corrosion, in advance. contact line and the pantograph zones with the return cir- Mains 400/230 V, 50 Hz AC DEHNventil ® DV M TT 255 FM 951 315
cuit as soon as the threshold voltage is exceeded. An ex- Traction power 462 V, 16.7 Hz
However, as well as earthing the tracks, special attention ample from the DEHN solutions portfolio is the lightning Type 1+2+3
should also be paid to the earthing of shelters (stops): resistant voltage-limiting device SDS 5. This device is capa-
if a lightning flash finds its way to earth in this area, there ble of returning to its initial state after discharging the im- Three-phase 400/230 V, 50 Hz AC DEHNguard ® DG M TT 275 FM 952 315
may be increased step voltage with fatal results! In order pulse current Single-phase 230 V, 50 Hz AC DG M TT 2P 275 FM 952 115
to comply with the duty to ensure public safety, measures Type 2
must be taken to eliminate this risk by way of precise po- We support you with our tried and tested concepts: so
tential control using special mesh mats. that people and systems are protected against the perilous Protection of data and information technology
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effects of lightning and surges at all times. I / O interfaces 24 V BLITZDUCTOR XT BXT ML4 BE 24 920 324
BXT ML4 BD 24 920 344
BXT BAS 920 300

Earthing
To protect against touch voltage Voltage Limiting Devices SDS 5 + 923 119
VLD-F Mast Adapter MA SDS M12 723 199

To protect against step voltage Grid Mat GMA 250 2000X1000X4 V4A 618 214
Connecting Clamp UEK 8.10 AQ3/4 M8 V4A 540 270
Earth rod StSt V4A TE 20 1500 AZ V4A 620 902

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