National lightning protection standards GB/T 50057 and GB/T 50343 stipulate that Surge Protective Devices (SPDs) shall be installed for lightning protection of buildings and electronic information systems.
A Surge Protective Device (SPD) protects power and signal lines against lightning-induced surges, transient overvoltages, switching surges, and electrostatic discharge (ESD) — diverting high-energy surges safely to earth.
Chenzhu C-Series SPD Applications
Category Protected Equipment
Power Supply Power distribution systems, automation systems, data centers, EV charging piles, wind turbines, shore cranes
Signal Lines Signal loops of PLC, DCS, SCADA, and RTU systems
Field Instruments Pressure/temperature/level transmitters, flow meters, solenoid valves, valve positioners
Communication Buses RS-485, RS-232, RS-422, CAN, APL bus
Product Selection
Chenzhu C-Series SPDs are classified into Power SPDs and Signal SPDs.
Power SPDs: Three discharge current levels — C2-20 / C2-40 / C2-80 — covering general industrial plants to high lightning-density regions. Compatible with TN/TT/IT grounding systems. Features failure indication and remote signaling.
Signal SPDs: Ultra-slim 3.5 mm design. Covers both intrinsically safe and non-intrinsically safe applications. Key lightning protection indicators: In, Imax, Iimp.
Power SPD (Type T2)
For AC/DC power system protection. Uses MOV + GDT combined protection. Lightning protection capability T2: 40/80 kA.
Selection Guide:
C2-20: Ideal for automation systems; low voltage protection level (Up).
C2-40: Suitable for power distribution systems.
C2-80: For high-protection requirements such as field distribution boxes and secondary distribution panels.
"F" suffix models: Include remote signaling function.
Signal SPD
Lightning protection capability: C2: 20 kV/10 kA; D1: 2.5 kA. Select the appropriate model based on application requirements. For intrinsically safe explosion-proof areas, select the intrinsically safe type (Ex ia IIC T6…T4 Ga certified), to be used together with safety barriers.
For loops with current > 800 mA (e.g., solenoid valves), the C-24P specification is available.
For failure indication and remote monitoring, the C FPro Series offers:
Visual Failure Indicator: LED window shows failure status at a glance. BUS-powered; signal loop faults do not affect indication.
Plug-in Design: All protection components are housed in the plug; the base is for wiring only. Replacing the plug renews the entire protection circuit.
Remote Monitoring: With remote monitoring module and DIN-rail BUS, supports switch or RS-485 output for control-room monitoring of SPD status.
Installation Essentials
Power SPD
A backup fuse must be connected in series upstream of the SPD (refer to selection table for specifications) to prevent system shutdown due to SPD aging or short circuit.
Upstream lead (L/N): ≥ 4 mm² copper conductor.
Downstream lead (PE): ≥ 6 mm² copper conductor.
Total lead length: ≤ 0.5 m recommended.
Signal SPD
Grounded via 35 mm DIN rail — no individual grounding required for each SPD.
Push-in terminals enable fast, tool-free wiring; supports 0.2–2.5 mm² conductors.
Intrinsically safe SPDs must be used with safety barriers to form an intrinsically safe loop with field instruments.
Knowledge Cards
1. Nominal Discharge Current — In (8/20 µs)
The surge current amplitude that an SPD can withstand multiple times (typically 5 positive + 5 negative impulses). This reflects the core lightning protection capability. Corresponds to T2 test waveform for power SPDs; C2 test waveform for signal SPDs.
2. Maximum Discharge Current — Imax (8/20 µs)
The maximum surge current amplitude that an SPD can withstand once. Typically Imax = 2 × In. Corresponds to T2 test waveform for power SPDs.
3. Impulse Discharge Current — Iimp (10/350 µs)
Simulates direct lightning strike current waveform. Corresponds to T1 test waveform for power SPDs; D1 test waveform for signal SPDs.
For detailed installation manuals, wiring diagrams, and cabinet assembly drawings:
📞 Chenzhu Technical Service: 400-881-0780
📧 Email: chenzhu@chenzhu-inst.com
Shanghai Chenzhu Instrument Co., Ltd.
Specialized in Industrial Automation Safety
