Mini-catalog · EN — Mini-catalog spread covering the 3EB2 and 3EB3 metal-oxide surge arresters for DC railway applications with VDV 525 "A1" and "A2" designations. It explains where A1 arresters protect the catenary and feeding sections and where A2 arresters limit fault-voltage rise between return line and structure earth, and provides full electrical and mechanical characteristics for six arrester variants covering nominal system voltages up to 3.0 kV DC, plus dimension drawings for both housing types.
The 3EB2 and 3EB3 surge arresters are designed for DC railway systems following the recommendations of VDV 525, Publication No. 525 of the Verband deutscher Verkehrsunternehmen (Association of German Transportation Companies), which advises DC railway operators on effective overvoltage protection against lightning strikes. The two housing types cover the VDV 525 "A1" (catenary/feeder protection) and "A2" (return-line-to-earth protection) functions.
Where the rails of a DC railway system are isolated from earth, a dedicated earth termination is needed — low-resistance tower footings, driven piles, the reinforcement of concrete tracks, or separate earth rods.
Rails without additional isolation generally have low leakage resistance and can themselves serve as earth terminations, with surge currents discharged directly through the rails. This, however, puts electrical and electronic equipment near or on the tracks at risk; fitting additional surge arresters within such equipment is an effective countermeasure.
Full protection of the catenary is achieved by installing outdoor surge arresters carrying the VDV 525 "A1" designation at every power feeding point, at the ends of feeding sections and dead-end feeders, at coupling points, and at current taps.
Where sections are frequently struck by lightning — for example on bridges or open stretches — additional A1 arresters are recommended.
Lightning protection of supply and return lines at substations requires A1-type arresters connected between the section circuit breakers or cable terminals and the return line, plus A2-type arresters between the return line and structure earth to limit the unavoidable potential rise a lightning surge current causes in the return line.
Although MOV surge arresters fail at rates well below 0.1 percent per year, a failure can leave an A1 arrester permanently conductive, producing an inadmissibly high fault voltage on the ground electrode for an extended time. An additional A2 arrester with a low continuous operating voltage (120 V ≤ Uc ≤ 300 V), connected between ground electrode and return line, is deliberately overloaded in this event: it limits the fault voltage and trips the section circuit breaker through feeding from the catenary system.
Six variants are offered. 3EB2 units carry arrester designation DC-B with a 2.5 As charge transfer rating; 3EB3 units carry DC-C with 7.5 As and correspondingly higher thermal energy ratings. All types have a nominal discharge current of 20 kA. Residual voltages are stated for 30/60 µs switching impulses (0.5, 1, 2 kA) and 8/20 µs lightning impulses (5, 10, 20 kA).
| Un [kV] | Ur [kV] | Uc [kV] | Arrester type | Function | Arrester designation | In [kA] | Qrs [As] | Wth [kJ] | Ures 30/60µs 0.5 kA [kV] | Ures 30/60µs 1 kA [kV] | Ures 30/60µs 2 kA [kV] | Ures 8/20µs 5 kA [kV] | Ures 8/20µs 10 kA [kV] | Ures 8/20µs 20 kA [kV] |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| – | 0.3 | 0.3 | 3EB2 003 - 7 D | A2 | DC-B | 20 | 2.5 | 3.0 | 0.6 | 0.6 | 0.6 | 0.7 | 0.7 | 0.8 |
| 0.75 | 1.0 | 1.0 | 3EB2 010 - 7 D | A1 | DC-B | 20 | 2.5 | 10 | 1.9 | 2.0 | 2.1 | 2.3 | 2.4 | 2.6 |
| 0.75 | 1.0 | 1.0 | 3EB3 010 - 7 D | A1 | DC-C | 20 | 7.5 | 26 | 1.8 | 1.9 | 2.0 | 2.1 | 2.2 | 2.3 |
| 1.5 | 2.0 | 2.0 | 3EB2 020 - 7 D | A1 | DC-B | 20 | 2.5 | 20 | 3.9 | 4.0 | 4.2 | 4.5 | 4.8 | 5.3 |
| 1.5 | 2.0 | 2.0 | 3EB3 020 - 7 D | A1 | DC-C | 20 | 7.5 | 52 | 3.6 | 3.8 | 4.0 | 4.2 | 4.4 | 4.7 |
| 3.0 | 4.0 | 4.0 | 3EB3 040 - 7 D | A1 | DC-C | 20 | 7.5 | 104 | 7.2 | 7.6 | 8.0 | 8.4 | 8.8 | 9.4 |
Mechanical data are common to each housing family: the compact 3EB2 (height 200 mm, 1.2–1.4 kg) and the larger 3EB3 (height 270 mm, 5.6–6.4 kg) with a longer creepage and flashover distance. All variants share a 40 kA rated short-circuit current, 25 kV lightning impulse withstand (1.2/50 µs), and 15 kV one-minute wet power-frequency withstand.
| Arrester type | Height H [mm] | Creepage distance [mm] | Rated short-circuit current Is [kA] | Lightning impulse withstand 1.2/50µs [kV] | Power frequency withstand 1 min. wet [kV] | Specified short-term load SSL [N] | Specified long-term load SLL [N] | Weight [kg] | Flashover distance [mm] |
|---|---|---|---|---|---|---|---|---|---|
| 3EB2 003 - 7 D | 200 | 133 | 40 | 25 | 15 | 160 | 110 | 1.2 | 127 |
| 3EB2 010 - 7 D | 200 | 133 | 40 | 25 | 15 | 160 | 110 | 1.3 | 127 |
| 3EB3 010 - 7 D | 270 | 219 | 40 | 25 | 15 | 160 | 110 | 5.6 | 210 |
| 3EB2 020 - 7 D | 200 | 133 | 40 | 25 | 15 | 160 | 110 | 1.4 | 127 |
| 3EB3 020 - 7 D | 270 | 219 | 40 | 25 | 15 | 160 | 110 | 5.9 | 210 |
| 3EB3 040 - 7 D | 270 | 219 | 40 | 25 | 15 | 160 | 110 | 6.4 | 210 |
Dimension drawings are provided for both housings. The 3EB2 is 200 mm tall overall (body height 160 mm) with a 100 mm wide hood, an 85 mm base width, 40 mm wide terminal straps, and Ø13 mm terminal holes offset 52 mm (top) and 55 mm (bottom) from the housing. The 3EB3 is 270 mm tall overall with a 179 mm wide triangular body (body height 230 mm), 71 mm body depth, 56.5 mm mounting offsets in the side view, 40 mm strap width, and Ø13 mm terminal holes.
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