Large areas can be defined as large plants with a few voltage levels, ranging from high voltage to low voltage, spread over a large area. In these sites, a large number of recording devices can be found relative to other areas.
A common event in part of the equipment can be reported due to threshold definition, or a different intensity of the event may be measured by each of the individual devices. In such an instance, part of the information is lost as a result of different threshold or intensity which affects the recording of the event.
Permanent recording saves all of the information without any loss of data, allowing for better analysis of the event consequences in the future.
The following example is an investigation of 1.5MW motor startup event in large area (pumping power station in New-Zealand) as reported by Siemens.
Figure 10 below describes two measurement points located a far distance from one another. The utility substation point was measured at 66KV and the pumping substation point was measured at 11KV.
Figure 10: Electrical diagram of a network in a large area