VLD Class Comparison for Railway Applications
Engineering comparison · EN 50526‑2
Railway voltage limiting devices: product comparison
Compare RW VLD class 1, class 2.1 and class 2.2 products by operating function, recoverability, polarity and current capability. The portfolio now includes the new RWVL2.1HP and RWVL2.2HP high‑performance variants, each rated for a recoverable short‑time current of 34 kA at 50 ms.
RW product portfolio
Compare RW VLD models
The values below compare representative products and the 120 V class 2 variants. Trigger‑voltage variants 60 V, 350 V and project‑specific values are available within the class 2 families.
Scroll horizontally if needed to compare all five models →
| Parameter | RWVL1 250 V / 500 V family | RWVL2.1‑120-(HS) Class 2.1 · standard performance | RWVL2.1HP‑120-(HS) NEW · Class 2.1 · high performance | RWVL2.2‑120-(HS) Class 2.2 · standard performance | RWVL2.2HP‑120-(HS) NEW · Class 2.2 · high performance |
|---|---|---|---|---|---|
| VLD type | VLD‑F · class 1 | VLD‑O+F · class 2.1 | VLD‑O+F · class 2.1 | VLD‑O+F · class 2.2 | VLD‑O+F · class 2.2 |
| Applicable product standard | Meets EN 50526‑2 requirements | Meets EN 50526‑2 requirements | Meets EN 50526‑2 requirements | Meets EN 50526‑2 requirements | Meets EN 50526‑2 requirements |
| Primary function | Fault protection, including defined OCL fault scenarios | Operational touch‑voltage limiting and fault protection within the approved application envelope | Operational touch‑voltage limiting and fault protection within the approved application envelope | Operational touch‑voltage limiting and fault protection with bipolar switching | Operational touch‑voltage limiting and fault protection with bipolar switching |
| Traction system / polarity | DC and AC · fault‑operated principle | DC · one primary switching polarity | DC · one primary switching polarity | DC and AC · both voltage polarities | DC and AC · both voltage polarities |
| Operation after defined load event | Non‑recoverable after a destructive fault event | Recoverable within rated load limits | Recoverable within rated load limits | Recoverable within rated load limits | Recoverable within rated load limits |
| Short‑time current | 25 kA / 100 ms non‑recoverable fault rating |
25 kA / 50 ms 18 kA / 100 ms, recoverable |
34 kA / 50 ms 24 kA / 100 ms, recoverable |
25 kA / 50 ms 18 kA / 100 ms, recoverable |
34 kA / 50 ms 24 kA / 100 ms, recoverable |
| Long‑time recoverable current | Not specified as a recoverable long‑time rating | >3 kA / 30 s | >3 kA / 30 s | >3 kA / 30 s | >3 kA / 30 s |
| Rated current, 60 min (body / HS) |
— | 130 A / 170 A | 130 A / 170 A | 180 A / 270 A | 180 A / 270 A |
| 120 V variant: UTn / UTi / Uw | DC sparkover: 250 V or 500 V | 120 V / 200 V / 110 V | 120 V / 200 V / 110 V | 120 V / 200 V / 110 V | 120 V / 200 V / 110 V |
| Leakage current | <1 µA | <2 mA at Uw | <2 mA at Uw | <2 mA at Uw | <2 mA at Uw |
| Monitoring option | Wireless remote status indication LoRaWAN; NB‑IoT on request LoRaWAN: 433 / 868 / 915 / 920 MHz · max. ERP +20 dBm |
Wireless (IoT) voltage and current monitor LTE‑M (NB‑IoT) |
Wireless (IoT) voltage and current monitor LTE‑M (NB‑IoT) |
Wireless (IoT) voltage and current monitor LTE‑M (NB‑IoT) |
Wireless (IoT) voltage and current monitor LTE‑M (NB‑IoT) |
| Impulse capability | Lightning current withstand: 150 kA | 40 kA (8/20) · 70 kA high‑current (8/20) · 25 kA (10/350) | 40 kA (8/20) · 70 kA high‑current (8/20) · 25 kA (10/350) | 40 kA (8/20) · 70 kA high‑current (8/20) · 25 kA (10/350) | 40 kA (8/20) · 70 kA high‑current (8/20) · 25 kA (10/350) |
| Response time | <1 µs | 25 ns surge protection · 1 ms UTi · 10 ms UTn* | 25 ns surge protection · 1 ms UTi · 10 ms UTn* | 25 ns surge protection · 1 ms UTi · 10 ms UTn* | 25 ns surge protection · 1 ms UTi · 10 ms UTn* |
| Protection / environment | IP66 · −40 to +80 °C | IP66 · −40 to +70 °C · indoor/outdoor · UV and salt‑spray resistant | IP66 · −40 to +70 °C · indoor/outdoor · UV and salt‑spray resistant | IP66 · −40 to +70 °C · indoor/outdoor · UV and salt‑spray resistant | IP66 · −40 to +70 °C · indoor/outdoor · UV and salt‑spray resistant |
| Designed service life | Dependent on fault events and replacement regime | 30+ years under specified operating and environmental conditions | 30+ years under specified operating and environmental conditions | 30+ years under specified operating and environmental conditions | 30+ years under specified operating and environmental conditions |
HS = with heatsinks; body = without additional heatsinks. OCL = overhead contact line. UTn = nominal triggering voltage; UTi = instantaneous triggering voltage; Uw = non‑triggering voltage. Class 2 rated currents at 60 minutes apply at 25 °C ambient with a 75 K temperature rise. Impulse waveforms 8/20 and 10/350 are given in µs. * Trigger delay values are factory adjustable. Final product selection, triggering configuration and installation must be reviewed for the traction system, fault envelope, national requirements and project conditions.
Application guidance
Select by function and fault envelope
Fault‑protection applications
Use where the required function is defined fault protection. After a destructive activation, the device becomes permanently conductive and must be identified and replaced.
Recoverable operation in DC traction
Suitable where operational touch‑voltage limiting is required and the application envelope is compatible with a single primary switching polarity. Polarity, recuperation and reverse‑direction energy require engineering review.
Recoverable protection for both polarities
Two anti‑parallel power thyristors support repeatable operation in both voltage polarities for demanding DC and AC traction applications, including operational and defined fault scenarios.
Technical summary
Current RW VLD portfolio at a glance
The new RWVL2.1HP and RWVL2.2HP extend the RW portfolio with high‑performance voltage limiting devices in VLD class 2.
RWVL2.1HP is a VLD‑O+F class 2.1 model for DC traction with one primary switching polarity.
RWVL2.2HP is a bipolar VLD‑O+F class 2.2 model for DC and AC traction and both voltage polarities.
Each HP model provides a recoverable short‑time current of 34 kA at 50 ms, 24 kA at 100 ms and a recoverable long‑time current above 3 kA at 30 seconds. The existing RWVL2.1 and RWVL2.2 standard‑performance products continue at 25 kA at 50 ms and 18 kA at 100 ms.
All RW voltage limiting devices meet the requirements of EN 50526‑2.
Frequently asked technical questions
What is the difference between RWVL2.1HP and RWVL2.2HP?
Both HP products reach the same recoverable current ratings: 34 kA at 50 ms, 24 kA at 100 ms and >3 kA at 30 seconds. RWVL2.1HP is class 2.1 for DC applications with one primary switching polarity. RWVL2.2HP is a bipolar class 2.2 design for both voltage polarities and for DC or AC traction systems.
Do the HP products replace RWVL2.1‑120 and RWVL2.2‑120?
No. The 25 kA standard‑performance models remain distinct products. The HP variants extend the portfolio for projects that require the higher recoverable short‑time rating of 34 kA at 50 ms.
How can online measurement and monitoring support a VLD installation?
RWVLM provides continuous measurement and remote evaluation with email, SMS and system alerts when a fault is registered. This enables targeted replacement of the affected VLD and reduces the time a failed device remains conductive, helping limit stray‑current corrosion. RWVLM can be integrated with RW or compatible third‑party VLDs after interface and installation review.
Can an RW class 2 VLD be used instead of a class 4 solution?
For many applications, an RW class 2 VLD can provide a technically suitable and cost‑effective alternative. The decision must be based on application‑specific engineering review, including the traction system, current and voltage profiles, protection coordination and project requirements.
Discuss the correct VLD configuration
Technical selection and project‑specific application support from RW Railway Technology.