Design Sheet: LPZ 0B to LPZ 1 – MSB Protection Criteria
By Tokai Engineering | Tech Team |
15 May 2025
Compliance with IEC 62305-4 and IEC 61643-11
1. Objective
To protect the electrical installation at the Main Switch Board (MSB) from high-energy transient overvoltages and partial lightning currents, as per IEC 62305-4. This applies at the LPZ 0B to LPZ 1 boundary where the electrical supply enters the building.
2. Surge Protection Device (SPD) – TMP 50kA/4
| Parameter | Value |
|---|---|
| Nominal Voltage (Un) | 400/230 V AC (3P+N+PE) |
| Maximum Continuous Voltage (Uc) | 275 V AC |
| Maximum Discharge Current (Imax) | 50 kA (10/320 µs) per mode |
| Voltage Protection Level (Up) | < 1.6 kV (L-N), < 1.5 kV (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 0B to LPZ 1 boundary protection requirement of IEC 62305-4 by integrating a high-performance Type 1+2 SPD (TMP 50kA/4) and a real-time TLSMS/03 monitoring system. The setup supports lightning event forensics, predictive maintenance, and system health visibility. Ideal for mission-critical infrastructure and high-risk zones.