Chapter 10 - Voltage Protection Functions
The dv/dt logic works by differentiating the RMS value of each phase voltage input, which can be with respect to
neutral, or respect to another phase depending on the selected measurement mode. This differentiated value is
then averaged over a number of cycles, determined by the setting dv/dt(n)AvgCycles and comparing this with a
threshold (dv/dt(n)Threshold) in both the positive and negative directions. A start signal is produced depending on
the selected direction (positive, negative or both), set by the setting dv/dt(n)Function, which can also disable the
function on a per stage basis. Each stage can also be blocked by the DDB signal dvV/dt(n)Blocking. The trip signal
is produced by passing the Start signal through a DT timer.
The function also produces three-phase Start and Trip signals, which can be set to Any Phase (where any of the
phases can trigger the start) or Three Phase (where all three phases are required to trigger the start). The
averaging buffer is reset either when the stage is disabled or no frequency is found (Freq Not Found DDB signal).