What are the symptoms, causes and solutions of impulse events?
A voltage impulse is a high-frequency voltage wave of positive or negative amplitude. An impulse that is measurable between current-carrying conductors is a normal-mode event; an impulse common to all current-carrying conductors and measurable with reference to ground is a common-mode event. Common symptoms of equipment suffering impulse events range from parity errors and component failure to hard-disk crashes, lock-up, memory scramble, SCR failure and power supply failure. Factors that influence the ability of an impulse to disturb a load include impulse amplitude, duration and frequency; system filter and bypass capacitors; semiconductor design and operating speed; and grounding. There are multiple causes for impulse events. Those potential causes include external sources, such as lightning, and internal sources, such as faulty wiring and circuit breakers, contact and relay closure, load startup or disconnect, SCR controlled loads and variable speed drives. Even photocopiers can be
