The system calculates the tan (d) of a unit as a relative value compared with reference voltage from another unit in service, thereby eliminating the need for a reference capacitor. The system is therefore a system based on relative tan (d) values.
Relative measurements and evaluation can reduce the effect of influences such as ambient temperature, operating voltages, loading conditions, different aging characteristics, different designs, operating conditions, etc.
The dictionary defines "continuous" as "without interruption". However, in the context of "continuous on-line monitoring" the selected time interval between measurements must be sufficiently short so that the process can be considered, for all practical purposes, continuous.
Sampling of all units in service occurs according to a user definable sampling schedule.
All measurements are tested for integrity against 3 parameters: RMS and mean of the signal, and tan (d) value calculated. Only measurements passing the integrity tests are stored in the database.