**A.** Impulsive transients

Impulsive transients are abrupt high magnitude actions that cause voltage and/or current levels to rise in either a positive or a negative direction for a very short period fewer than 50 ns.

**B.** Oscillatory transients

An oscillatory transient is an abrupt variation in the steady-state voltage, current, or both, fluctuating at the natural frequency of the system at both the positive and negative directions.

Events causing transients occur from different reasons such as lightning strikes, poor grounding system, electrostatic discharge, inductive load switching, and fault clearance. Transients may lead to probable data loss in computers, malfunction of electronic equipment, and microprocessor-based protection relays.
