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Let-through voltage
The larger the transient overvoltage reaching the electronic
equipment, the greater the risk of interference, physical damage
and hence system downtime. Therefore, the transient overvoltage
let-through the protector should be as low as possible and certainly
lower than the level at which interference or component degradation
may occur.
Transient overvoltages can exist between any pair of conductors: |
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phase
to neutral, phase to earth and neutral to earth on mains
power supplies, |
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line
to line and line(s) to earth on data communication, signal
and telephone lines. |
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Thus, a good protector must have a low let-through voltage between
every pair of conductors.
Let through voltage should be quoted for a relevant standard
test. |
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| The
boxed section outlines location categories, exposure levels
and their peak voltages and currents. An explanation of transient
testing is given in Appendix C of the Electronic
Systems Protection Handbook. |
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| 5 |
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