Transient voltage suppressors (TVS’s or TransorbsTM) are silicon avalanche diodes that limit damaging voltage spikes through a clamping action, reducing the amplitude of the transient to a nondestructive level. TVS’s have faster response times and do not exhibit the wear-out characteristics associated with MOV’s. They are available in unipolar and bipolar versions; the later being an excellent choice for suppressing both positive and negative supply-line transients normally encountered in rail and transit applications