Design Sheet: LPZ 1 to LPZ 2/3 – SDB & DB Protection Criteria
By Tokai Engineering | Tech Team |
15 May 2025
Compliance with IEC 62305-4 and IEC 61643-11
1. Objective
To provide effective surge protection for Sub-Distribution Boards (SDB) and Distribution Boards (DB) by mitigating residual surges transmitted from upstream surge protection devices, as per IEC 62305-4. This applies at the LPZ 1 to LPZ 2/3 boundary.
2. Surge Protection Device (SPD) – TMP 320/4
| Parameter | Value |
|---|---|
| Nominal Voltage (Un) | 400/230 V AC (3P+N+PE) |
| Maximum Continuous Voltage (Uc) | 275 V AC |
| Maximum Discharge Current (Imax) | 40 kA (8/20 µs) per mode |
| Voltage Protection Level (Up) | < 1.5 kV (L-N, N-PE) |
| Response Time | ≤ 25 ns |
| Disconnection Mechanism | ≤ Thermal fuse + window indicator |
| Remote Indication Contact | ≤ Yes, Isolated Form C |
| Compliance | ≤ IEC 61643-11:2011, CE Mark |
3. Smart Monitoring System – TLSMS/03
| Feature | Description |
|---|---|
| Surge Event Counter | Lightning strike count with timestamp |
| Surge Amplitude Logging | Measured energy of each surge (kA) |
| SPD Status Monitoring | Real-time SPD health tracking |
| Grounding Resistance Monitoring | Detects grounding path status |
| Voltage Anomaly Detection | ≤ Over/under voltage alerts |
| Communication Interface | ≤ RS-485 (Modbus protocol) |
| Integration | ≤ Compatible with BMS, SCADA, cloud |
| Certifications | ≤ KEMA Certified, IEC 61643-11 compliant |
4. Compliance & Risk Management Notes
This design fulfills the LPZ 1 to LPZ 2/3 boundary protection requirement of IEC 62305-4 by using the TMP 320-4 Type 2 SPD for surge reduction, combined with TLSMS/03 for diagnostics and operational awareness. This ensures protection for downstream sensitive equipment such as computers, servers, and control panels, while enhancing maintenance scheduling and system uptime visibility.