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Frequently
Asked Questions on
Surge Protection |
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| Why is
surge protection needed? |
Surge Protection Devices (SPD)
prevent upset or damage to sensitive equipment, thereby preventing
significant economic loss due to downtime. |
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| Where
do transients come from? |
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Lightning: 9 to 20 million strikes a year in USA alone. |
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Utility generated switching surges. |
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Elevators, welding machines, copiers,
air conditioners, etc. |
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Scheduled test operation of equipment such as standby motor-generator
sets. |
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| Where
are surge protectors most helpful? |
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Production lines - to ensure continuous operation. |
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Sensitive computer-controlled machinery. |
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Banks, investment firms, brokerages, etc. |
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Critical military and emergency response sites. |
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Consulates, airports, malls, hospitals, etc. |
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| Why is
low "let-through" voltage critical for sensitive equipment? |
Surge protectors divert very
large transient surge currents to ground. However, sensitive equipment
will be exposed to the SPD's clamping voltage plus the voltage drop
across its connecting cable. The equipment is not properly protected
unless the "let-through" voltage is considered. |
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| Are there
other concerns regarding SPDs? |
Yes. One should expect a useful
life of at least 20 years. SPDs may fail from a direct lightning
strike, but this is a rare occurrence. Internal MOV damage more frequently
occurs due to excessive AC line voltages. |
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