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It was previously stated that power quality can be responsible for financial loss with examples quoted of financial institutions losing millions with just a few glitches. Obviously, this happens on smaller scales too with common problems being a few corrupted files on a computer needing a little time (and money) to sort out. However, one of the most serious issues associated with power quality is when there is a loss of time as well as equipment. When the odd piece of equipment fails it is often attributed to "electronics not being perfect", but when it starts happening over and over one needs to investigate if there is something more sinister. There is a basic rule when dealing with equipment failure and that is to remember Voltage does not damage Now I know this is a controversial statement, especially if one refers to the sections where we categorically claim that both under-voltage and over-voltage can damage circuitry. However, if one reads the statements properly there is no denying that it is not the voltage (or lack thereof) that causes the damage. The real rule is Current does! To prove the point; Have you ever walked past a metal doorframe and been whacked by a spark that seemed to jump out of nowhere? Have you thought of the voltage that must have existed between you and the frame? Try a good few thousand volts (if not into the tens of thousands!). Yet did this kill you? So if this high voltage did not kill then why would accidentally strapping yourself to 230V have a rather terminal effect? I think you've cottoned on! The same thing exists with electronics. Actually, electrical installations have the same problem, just the currents involved are a lot larger. Now that understanding it is excessive current that damages, let's investigate the various forms of component damage. What will be recognised is the seemly high concentration on the power supply. The reason is simple, this is the first piece of electronics that interfaces with the incoming mains and it stands to reason that this would suffer the damage when subjected to bad power (although it does not stop there!). Although a lot is focused on modern-day switch-mode power supplies, component failure can happen in simpler power supplies too and fault analysis is done by applying the relavent bits from the following sections. Before proceeding onto component failure we need to grasp the true concept of "Running Voltage". Simply put, 230VAC does not mean electronics runs at this voltage! "Component Failure" attempts to identify how to identify certain relationships between certain components failing and bad power.
© 28.02.02 |
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