A transient voltage suppression diode is a device used to protect sensitive electronics from voltage spikes induced on connected wires. It is also commonly referred to as a transorb, after the brand name TranZorb registered by General Semiconductor (now part of Vishay). A transient voltage suppression diode may be either unidirectional or bidirectional. A bidirectional transient voltage suppression diode can be represented by two mutually opposing zener diodes in series with one another and connected in parallel with the circuit to be protected. While this representation is schematically accurate, physically the devices are now manufactured as a single component. The device operates by shunting excess current when the induced voltage exceeds the zener breakdown potential. A transient voltage suppression diode can respond to over-voltages faster than other common over-voltage protection components such as varistors or gas discharge tubes. This makes transient voltage suppression diodes useful for protection against very fast and often damaging voltage transients. These fast over-voltage transients are present on all distribution networks and can be caused by either internal or external events, such as lightning or motor arcing.
