DK-20 power supply series modular surge protective device(SPD) is designed according to IEC61643 standard. It is accordance with the criterion of Low-voltage Surge Protective Devices-Part 1: Surge Protective Devices Performance Requirements and Test Method of Low-voltage Power Distribution System. With good sealing, it is designed as module and 35mm DIN-Rail Mounting. With working indication window, temperature control circuit breaker and built-in over-current protective� circuit, the modular SPD can release automatically to avoid fire danger when it breaks down. With remote alarm connector, it is convenient for remote monitoring. The main module and the base are replaceable. The lightning protection modes is L-PE, N-PE (2P/4P) or L-N-PE (1+1) / (3+1).