TSU1 surge protector is mainly applied to limiting amplitude value of transient over voltage, absorbing, consuming, discharging surging current energy in the electric wiring of AC 50/60Hz, rated working voltage 230V, surging through flow capacity not more than 50A. It is used in the occasion of higher type of over voltage which can make the protected electrical component transferring from one type of over voltage to another lower type of over voltage. It is adapted for composing combined electrical equipment with other module terminal electrical equipment so that it can increase installation types and expand range of using, or further step down over voltage on using terminals to protect TV set, hi-fi sound and such kinds of electrical appliances or the facilities like computer, microcomputer. Protector applies to power utilization for household and the similar places, facilities for inputting circuit in the thunder direct stroke or protecting from the damage of the surging current caused by outdoor arrester. The products comply with IEC61643.