Voltage surge problems range from catastrophic failures on I/O boards and other electronic equipment to unpredictable network or computer glitches.
Computers and network equipment are highly susceptible to damage by data line voltages above specific levels. Local area network transceiver interface circuits may be damaged by as little as 17 volts. Less than 15 volts can scramble data and compromise network reliability.
Data line voltage surges are created in several ways. Lightning is the most of dramatic cause. A lightning strike can cause catastrophic system damage even with building entry point protectors in place. Even a near miss can induce destructive voltages in data lines.
Damaging surges are also created when the electrical ground for equipment shifts in relation to the data line connected to it. Ground is necessary for system operation because it is a reference point for the data signals carried by the data line. Computers and other equipment read signals with respect to ground.
A brief upward shift in ground potential is sufficient to damaged sensitive electronics. All it takes is a shift longer than 10 nanoseconds. What causes ground potential to shift? Lightning can be the culprit, along with any of the transient load factors that affect a power system. Even electrostatic discharge, which can reach upward of 20,000 volts, can wreak havoc on network interface cards and other sensitive electronics. On-and-Off operation of electric motors and other electrical equipment can cause shifts in ground potential. When electrical loads return to ground, as they do in building electrical power systems, the normal momentary power surge will lift the ground potential due to the inductance of the wiring. The operation of surge suppressors that protect electrical equipment and other protective devices, such as UPS equipment can cause momentary shift in ground potential. Connetced equipment is shielded from power line surges, but when the suppressor diverts excess voltage to ground, ground potential will spike upward.
The only sure solution for voltage problems is protection of equipment at the data ports. The protector clamps all lines to ground when any line’s voltage is too high. The ground wire from the protector to equipment chassis is short to prevent the protector from causing large voltages when it operates.
