Boltek EFM-100 v.2 - Manual (Page 21)

C H A P T E R 2 - I N S T A L L A T I O N
15
Figure 16: Correcting a Field Mill using a Reference Field Mill
permanent
reference
correction

Once you have calculated the required sensitivity reduction (correction factor) you can
calculate the resistor value needed for the Sensitivity Plug.
 



k
correction
k
resistor 100
) 1 (
100
For most installations it is not necessary to correct using a reference field mill. It is usually
sufficient to choose a sensitivity plug which produces a fair-weather electric field of
approximately 0.1 kV/m and does not saturate (above -20 kV/m or +20kV/m) during
most thunderstorms. Electric field trends and sudden changes (lightning) are of much
more interest than an exact absolute value. Alarm set points can be lowered to increase
alarm sensitivity or increased to reduce the frequency of nuisance alarms.