A lumped parameter model which includes capacitances
should be sufficient to examine the influence of inductive
VTs on transient measurements obtained using a power
quality monitor, given the typical sample frequencies used. It
would be ideal if a wide band model were available for every
inductive VT used for power quality measurements. The
problem with this approach is that wide band models are
complex, and require each VT transfer function to be
measured over a wide range of frequencies. Constructing a
low frequency model, using 50Hz data, is comparatively
simple. This low frequency model is insufficient to represent
the VT behaviour beyond a few hundred Hertz. The addition
of lumped capacitances to the low frequency model extends
the bandwidth to several kHz. Measuring the stray
capacitances of a particular VT is still fairly onerous, but the
model is much simpler than that needed for a wide band
model.