The metal-oxide varistors can be used in terminal design. They are approved for a maximum sine-wave-form power-frequency operating voltage, which is printed on the component. Any voltages greater than the permitted maximum are discharged safely within 25 ns. Varistors are used for medium to high power.
Suppressor diodes work similarly as conventional Zener diodes. The diode becomes conductive within 10– 100ps after a certain breakdown voltage, set by the manufacturer, is exceeded. Compared to Zener diodes, suppressor diodes have a higher current-carrying capacity and a shorter reaction time.
Gas-discharge tubes / sparkover gaps (GDT) are designed with a terminal shape. They are approved for a maximum DC voltage, which is printed on the component. Any voltage greater than the amount specified is safely discharged within about 10-100µs. Gas arresters can be used for high-power applications.