The basic symptom of poor power management is an unreliable source. When the odd PC is used in a home storing the household accounts and it should 'crash' through 'dirty' power then the household accounts may be a little muddled for a while but it is most unlikely to cause financial ruin to the household in question. However, dirty power in e.g. a banking institution could very well cause financial losses of millions. It was quoted by one banking firm that a mere glitch on their power would result in a £0.5 million loss! This statement could be used as a basis for defining the primary symptom of power quality - "power quality problems result in financial loss" One can obviously use this statement in a proportional way being "the higher the pending financial loss, the more effort should be put into ensuring power quality". This raises the question "what is power quality and what are the symptoms?". It must be remembered that Power Quality is a perception issue. To illustrate the point take the following hypothetical scenario; On Main Street is Williams' Welding Works utilising hefty electric arc welders. The lights may dip while welding but according to him there is no problem. The power is solid and it's available 24/7 and he produces good welds. Mrs. Jones of Rosemount avenue, leading off Main Street, has had enough and has complained to the local electricity supplier about flickering lights. According to the above Mrs. Jones can be perceived, and correctly so, to have solid, 24/7 power. There is tons available to drive bar heaters, washing machine, microwave, etc. with more than enough to spare. But having the table lamp flicker in unison with Williams' welders while watching TV destroys any pleasure that may be gained from her activities. So, is there a power quality issue? Yes there is! This sort of complaint has an impending financial loss. It may come in the form of headache tablets, but it is still costing her money. Something will need to be done. It may involve costs of putting the house on a separate feed, but it will be necessary for the sake of Mrs. Jones' sanity. I've divided up this chapter in to some general areas, starting with the main issues and then moving on to more defined areas where power quality issues manifest themselves. Why symptoms are suffered is covered as an introduction. Then the specifics, and start with Heat. This is usually the primary output or indicator of power quality problems. Following on from this are the primary causes of heat and, as motors form a large part of life (i.e. inductive loads), we start with "artificial consumption". Having a bad power factor can attribute to extremely high losses on a network. Then tackled is "Annoyances". The reason is wavy computer screens, crackling radios, or other such disturbances are often not associated with power quality. The difference between the previous section and "Equipment Malfunction" is in this section I deal with equipment actually not performing the tasks it is intended to do. And finally escalate to actual "Equipment Failure", where the power is directly (although it may appear indirectly) responsible for components failure. Why symptoms are suffered >>
© 12.04.02 |
Symptoms