STE T23 20 is the series of combined Type 2+3/Class II+III devices for discharging voltage surges while providing a very fine voltage protection level, in accordance with EN/IEC 61643-11. Complete with a built-in powerful EMI filter. Suitable as the final stage of protection in installations with electromagnetic disturbances which might interrupt, degrade or limit system performance. Series connection for applications up to 20A rated current.