RS485 Signal Surge Protector
Best Protection for Industrial Control Lines
The best RS485 signal surge protector protects RS485 and RS232 industrial control bus lines from lightning-induced transients, switching surges, and electrostatic discharge. TPKXJ Series RS485 signal surge protector: for PLC, SCADA, motor control, and building automation. 6–110Vdc. DIN rail and panel mount. IEC 61643-21 compliant. Factory-direct wholesale — OEM & ODM ready.
RS485 / RS232 Surge Protectors — TPKXJ Series
The TPKXJ RS485 signal surge protector series protects industrial control bus lines from lightning damage, switching transients, and ESD. Hybrid GDT and Diode technology: <10ns response, fail-safe self-protected design, low residual voltage. Every RS485 signal surge protector in the TPKXJ range is compliant with IEC 61643-21 — the international standard for signal line surge protection. Supplied to panel builders and automation integrators in 50+ countries.
For RS485 networks requiring protection of 1 or 2 wire pairs. Screw terminal connection with optional DIN rail mounting. Suitable for all working voltages from 6 to 48Vdc.
Optimized for 12V RS485 networks requiring protection of 2 wire pairs simultaneously. Same Hybrid GDT and Diode technology with low residual voltage at 12V nominal.
DIN rail mounted RS485 SPD for industrial control cabinets. Wide voltage range including 110Vdc. Higher working current (2500mA) and lower series resistance (3Ω) for high-current bus applications.
RS485 SPD Technical Specifications — TPKXJ Series
| Model | Un (Vdc) | Uc (Vdc) | In (8/20µs) | Imax | Up | IL | RS | Pairs | Mount | Housing | Standard |
|---|---|---|---|---|---|---|---|---|---|---|---|
| TPKXJ-2 | 6/12/24/48 | 8/15/30/65 | 5kA | 10kA | ≤12/25/60/75V | 1000mA | 15Ω | 1 pair | Optional DIN | Aluminum | IEC 61643-21 |
| TPKXJ-4 | 6/12/24/48 | 8/15/30/65 | 5kA | 10kA | ≤12/25/60/75V | 1000mA | 15Ω | 2 pairs | Optional DIN | Aluminum | IEC 61643-21 |
| TPKXJ-12V-4 | 12 | 15 | 5kA | 10kA | ≤25V | 1000mA | 15Ω | 2 pairs | Optional DIN | Aluminum | IEC 61643-21 |
| TPKXJ-x-DIN | 6/12/24/48/110 | 8/15/30/65/175 | 5kA | 10kA | ≤12/25/60/75/250V | 2500mA | 3Ω | 1 pair | DIN 35mm | PA66 | IEC 61643-21 |
All models: SPD Type C3 · Response <10ns · IP20 · −40°C to +80°C · Altitude 4,000m · Terminal connection: screw pressure · Max conductor: 4mm² solid / 2.5mm² flexible · Torque: 0.5Nm
Why Industrial RS485 Lines Require Surge Protection
RS485 buses often run hundreds of metres between industrial equipment — PLCs, sensors, variable frequency drives, and SCADA terminals. Long cable runs act as antennas for lightning-induced surges, and switching transients from motors or contactors can destroy RS485 transceivers instantly.
Combines Gas Discharge Tube with diode clamping for fast response (<10ns) and low residual voltage. Protects both differential RS485 signal pairs simultaneously.
In the event of component failure, the SPD disconnects from the line — preventing a failed protector from disrupting the bus. Critical for 24/7 industrial automation systems.
TPKXJ standard models: RS=15Ω. DIN rail model: RS=3Ω. Lower series resistance maintains signal integrity over long RS485 bus runs with multiple nodes.
TPKXJ-x-DIN mounts directly on standard 35mm DIN rail inside control panels — no additional hardware required. 18mm wide, 92mm tall.
Which Model Do You Need?
Choose based on your system voltage, number of pairs, and installation method:
| Requirement | Recommended Model |
|---|---|
| Single RS485 pair, 24V system | TPKXJ-2 (24V) |
| Two RS485 pairs, 6–48V | TPKXJ-4 |
| 12V fixed, 2 pairs | TPKXJ-12V-4 |
| DIN rail mount, up to 110Vdc | TPKXJ-x-DIN |
| High-current bus (≥2A), control cabinet | TPKXJ-x-DIN (RS=3Ω) |
Not sure which model to specify? Send us your bus voltage, cable length, and number of nodes — our engineers will recommend the right model within 24h.
RS485 Surge Protector Applications
Industrial Automation & PLC Systems
- PLC-to-field device RS485 bus lines
- Variable frequency drives (VFD) communication
- Conveyor system sensor and actuator networks
- Motor control centres and SCADA terminal protection
Building Automation & HVAC
- BACnet/Modbus RS485 building management systems
- HVAC controller networks across large buildings
- Energy metering and sub-metering bus lines
- Access control and fire alarm communication
Telecom & Data Infrastructure
- RS485 bus in telecom equipment rooms
- UPS remote monitoring communication lines
- DC power system control and monitoring (−48V)
- Medical equipment serial interface protection
Why Source Your RS485 Signal Surge Protector from TrilPeak?
TrilPeak is a vertically integrated RS485 signal surge protector manufacturer — in-house MOV production, 100% routine testing, IEC 61643-21 compliant. Every TPKXJ RS485 signal surge protector is supplied direct to panel builders, OEM brands, and automation integrators worldwide.
IEC 61643-21 Certified
TPKXJ series certified to IEC 61643-21 and EN 61643-21. CE Declaration of Conformity and full test reports available on request.
In-house MOV Production
TrilPeak manufactures its own varistor components — direct control over material quality, production consistency, and performance validation.
25 Years · 50+ Countries
Trusted by panel builders, system integrators, and automation contractors worldwide. 20,000m² factory with 100% routine testing on all products.
OEM / ODM Ready
Custom voltage ratings, housing colours, and branding supported. Sample in 7 days. Flexible MOQ for distributors and panel builders.
RS485 Signal Surge Protector — Buyer FAQ
How does an RS485 signal surge protector protect RS485 lines?
The TPKXJ RS485 signal surge protector uses Hybrid GDT and Diode technology. During a surge event, the GDT conducts first (handling high energy), followed by diode clamping to limit residual voltage below the RS485 transceiver's damage threshold — all within <10ns. Under normal conditions, the RS485 signal surge protector circuit is fully transparent and does not affect signal quality.
Will the series resistance (15Ω / 3Ω) cause problems on my RS485 bus?
For most RS485 applications, a 15Ω series resistance per protector is acceptable — RS485 typically operates within ±50V common-mode range with transceivers tolerant of line impedance. For longer bus runs or high-node-count systems, use the TPKXJ-x-DIN with RS=3Ω, which minimises signal attenuation while still providing full surge protection.
Where should an RS485 signal surge protector be installed?
Install an RS485 signal surge protector at every building entry point where RS485 cables enter from outdoors, and at both ends of long cable runs (>30m) exposed to lightning risk. For indoor systems, install the RS485 signal surge protector at panel entry points near PLC or SCADA equipment. The TPKXJ-x-DIN mounts directly on DIN rail inside control cabinets.
Can TPKXJ protect RS232 serial lines as well?
Yes. RS232 operates at ±12V and most TPKXJ models are suitable for RS232 protection. Select the 12V nominal voltage variant (TPKXJ-12V-4 or TPKXJ-DIN 12V) to ensure the protection voltage level (Up ≤25V) is safely below the RS232 transceiver's maximum input rating.
What is the maximum working current supported?
TPKXJ-2/4 and TPKXJ-12V-4 support up to 1000mA (1A) maximum working current. The TPKXJ-x-DIN supports 2500mA (2.5A), making it suitable for high-current RS485 applications such as long runs to multiple sensors or actuators.
What certifications are included with the TPKXJ series?
All TPKXJ models are certified to IEC 61643-21 and EN 61643-21. CE marking is included. Declaration of Conformity (DoC) and full test reports are available from TrilPeak upon request — important for project specifications and panel builder documentation.
Guides & Related Products
Request a Quote — RS485 Signal Surge Protectors
TrilPeak supplies the best RS485 signal surge protectors to panel builders, system integrators, and OEM manufacturers in 50+ countries. IEC 61643-21 compliant. Factory-direct pricing. Samples in 7 days.