Analog Signal Protection – RayDat Series
The Raycap RayDat analog signal protection series is a modular SPD family developed for the protection of measurement, control, and communication circuits against lightning-induced surges. With its GDT (coarse protection) + SAD (fine protection) hybrid structure, it provides both common mode and differential mode protection. Key features include high density up to 4 lines in 12 mm width, uninterrupted line connection during module replacement, and ATEX/IECEx certified Ex versions.
Analog signal lines — 4-20 mA loops, sensor cables, measurement, and control circuits — often cover long distances and pass through open areas. These lines are vulnerable to lightning-induced surges; damage to a transmitter or PLC input card leads to production loss far exceeding the cost of the device.
The RayDat series is a modular SPD family designed for the protection of these lines. The devices feature a multi-stage structure:
- Coarse protection stage: A three-pole gas discharge tube (GDT) that diverts primary impulse energy to ground.
- Fine protection stage: A fast bidirectional silicon avalanche diode (SAD) that reduces residual voltage to a level tolerable by sensitive electronics.
The fine protection stage is designed to avoid capacitive line loading — meaning low insertion loss and a wide operating frequency range (up to 30 MHz). Series line impedances between stages ensure energy coordination between the two stages at every impulse level; no voltage or impulse current "blind spots" occur.
The decisive safety element of the series is the thermo-clip. When a mains frequency contact occurs between the power line and the communication line ("mains incursion"), this creates a risk of electric shock and fire. The thermo-clip in the primary protection stage eliminates this risk by diverting the mains frequency current to ground.
Thanks to the pluggable module/base design, an end-of-life module can be replaced without disconnecting system wiring. The critical point is: when the module is removed from the base, the connection lines remain active — meaning replacing the protection module does not interrupt production or communication.
The products comply with IEC/EN 61643-21 and UL 497B 4th Edition standards; many models are UL Listed. Classification: D1 / C1 / C2 / C3. 35 mm DIN rail mounted, available with screw or quick-connect (spring) terminals.
Product families:
- RayDat SL Series — Basic modular protection. SLH-2 (single pair), SLH-4 (two pairs), SSH-3 (shielded cable), SLL-4 (fine protection only), SUI-4 (high capacity for open lines)
- RayDat SRH Series — Version with remote signal contact. The contact changes position in case of failure. The SRH-2L model also features an LED visual indicator.
- RayDat SP Series — For ungrounded double loops. Designed for sites with high ground potential rise, such as near electric railways. SPH-2, SPH-4, SPI-2, SPI-4.
- RayDat Ex Series — ATEX/IECEx certified versions for explosive atmospheres. Ex-2 (DIN rail) and PLP Ex family (stainless steel, IP54, with conduit connection).
Common features
- Multi-stage hybrid protection: GDT (coarse) + SAD (fine)
- Common mode (longitudinal) and differential mode (transverse) protection
- Very high impulse withstand values
- Connection lines remain active during module replacement
- High density — up to 4 protected lines in only 12 mm width
- Energy coordination between stages (series line impedance)
- Thermo-clip — fire and shock protection against mains incursion
- Low insertion loss, wide frequency range (up to 30 MHz)
- Screw or quick-connect (spring) terminal options
- Potential-free contact version for fault detection (SRH series)
- LED visual fault indicator on some models (SRH-2L)
- Direct / indirect shield grounding options
- 35 mm DIN rail mounting (IEC/EN 60715)
- Housing: gray thermoplastic, V-0 flame resistance
- Protection class: IP 20 (embedded)
- Operating temperature: -40 °C … +80 °C
- Classification: D1 / C1 / C2 / C3
- Standards: IEC/EN 61643-21, UL 497B 4th Edition
Model comparison — RayDat SL Series
| Model | Protected line | In (8/20 µs) | Imax (8/20 µs) | Iimp (10/350 µs) | Voltage (V DC) |
|---|---|---|---|---|---|
| SLH-2 | 1 pair (2 conductors) | 10 kA | 20 kA | 2.5 kA | 5, 12, 15, 24, 30, 48, 60 |
| SLH-4 | 2 pairs (4 conductors) | 10 kA | 20 kA | 5 kA | 5, 12, 15, 24, 30, 48, 60 |
| SSH-3 (shielded cable) | 1 pair (2 conductors) | 10 kA | 20 kA | 2.5 kA | 5, 12, 15, 24, 30, 48, 60 |
| SLL-4 (fine protection only) | 2 pairs (4 conductors) | 250 A | — | — | 30 |
| SUI-4 (open lines) | 2 pairs (4 conductors) | 20 kA | 30 kA | 5 kA | 5, 12, 15, 24, 30, 48, 60 |
Model comparison — RayDat SRH and SP Series
| Model | Protected line | In | Imax | Iimp | Voltage | Feature |
|---|---|---|---|---|---|---|
| SRH-2 | 1 pair | 10 kA | 20 kA | 2.5 kA | 5–60 V | Remote contact |
| SRH-2L | 1 pair | 10 kA | 20 kA | 2.5 kA | 5, 12, 24, 30 V | Remote contact + LED |
| SPH-2 | 1 pair | 10 kA | 20 kA | 2.5 kA | 30 V | Ungrounded loop |
| SPH-4 | 2 pairs | 10 kA | 20 kA | 5 kA | 30 V | Ungrounded loop |
| SPI-2 | 1 pair | 10 kA | 20 kA | 2.5 kA (total 5 kA) | 30 V | Ungrounded loop |
| SPI-4 | 2 pairs | 10 kA | 20 kA | 2.5 kA (total 10 kA) | 30 V | Ungrounded loop |
Remote contact ratings: AC 250 V/0.5 A — DC 50 V/1 A
Typical electrical values (SLH-2 example)
| 5 | 12 | 15 | 24 | 30 | 48 | 60 | |
|---|---|---|---|---|---|---|---|
| Nominal operating voltage Un | 5 V | 12 V | 15 V | 24 V | 30 V | 48 V | 60 V |
| Max. continuous operating voltage Uc | 6 V | 15 V | 18 V | 28 V | 33 V | 52 V | 64 V |
| Residual voltage @5 kA Ures | < 22 V | < 42 V | < 48 V | < 70 V | < 80 V | < 140 V | < 160 V |
| Insulation resistance Riso | ≥ 6 kΩ | ≥ 15 MΩ | ≥ 18 MΩ | ≥ 28 MΩ | ≥ 33 MΩ | ≥ 52 MΩ | ≥ 64 MΩ |
- Rated load current IL: 1 A (25 °C) — SLL-4 and SPH-4-30/0: 10 A
- Response time tA: < 1 ns (line-line, line-ground)
- Series resistance R per path: 1.6 – 2.0 Ω (SLL-4: 0.1 Ω)
- Transverse capacitance C: 50 pF (shield-ground: 5 pF)
- Cut-off frequency fG: 30 MHz
- Terminal cross-section: max. 4 mm² (Q version 2.5 mm²)
- Dimensions: 12 mm width, DIN 43880 2/3 TE — Weight: 52–70 g
RayDat Ex Series — Explosive atmospheres
| Ex-2 | PLP Ex family | |
|---|---|---|
| Mounting | 35 mm DIN rail | Conduit connection (1/2" NPT, M20×1.5, G 1/2") |
| Housing | Thermoplastic, IP 20 | Stainless steel, IP 54 |
| Voltage | 12, 24 V DC | 24, 48, 24/5 V DC |
| In (8/20 µs) | 5 kA | 5–10 kA |
| Imax (8/20 µs) | 10 kA | 10–20 kA |
| Iimp (10/350 µs) | 1 kA | 1.0–2.0 kA |
| Ex class | II 1G Ex ia IIC T* Ga | Ex ia IIC T6 Ga / Ex ia IIIC T85 °C Da |
| Temperature | -40 °C … (according to temperature class) | -30 °C … +60 °C |
| Standards | IEC/EN 60079-0, 60079-11 | + UL 60079-0/-11, CAN/CSA C22.2 |
- Ex-2 intrinsic safety: Ui 16/29 V, Ii 500 mA, Pi 2 W, Ci 10 nF, Li 0.11 mH
- PLP Ex intrinsic safety: Ui 50 V, Ii 800 mA, Pi 2 W, Li 60 µH
The RayDat analog signal protection series is used in signal lines of measurement and control infrastructure:
- 4-20 mA current loop lines — between field instrument and control system
- Pressure, temperature, level, and flow transmitters — field measurement devices
- PLC / DCS analog input-output cards — control system side
- Instrumentation and marshalling panels — signal collection points
- Shielded signal cables — including shield protection with SSH-3 series
- Explosive atmospheres (ATEX/IECEx) — petrochemical, refinery, gas facilities (Ex series)
- Facilities near electric railways — high ground potential rise (SP series)
- Ungrounded double loops — SP series
- Long signal lines passing through open areas — high-capacity protection with SUI-4
- Remotely monitored facilities — fault information transfer to SCADA with SRH series
- Water and wastewater facilities — remote pump station instrumentation
- Power plants and substations — measurement and control circuits
- Panels with space constraints — 4-line protection in 12 mm width
- Facilities requiring continuous operation — line remains active during module replacement
