The inductive voltage transformers (VTs) used on
the power system are primarily designed for protection or
metering at 50Hz. The leakage inductance of the VT windings
and stray capacitances can form a resonant circuit. When
subjected to AC voltages at frequencies well below resonance,
the VT can be assumed to behave linearly giving accurate
measurements. The resonance of the VT limits the bandwidth
over which it may be used to provide accurate measurements.
This is of particular importance when taking harmonic and
transient measurements. This paper reviews the different kinds
of VT model available. A model is selected for transient
simulation in EMTP, and the influence of the VT model on
switching transients is examined. A key observation is that
when the inductive VT model is subjected to a step change in
voltage, a voltage ripple is introduced at the VT’s resonant
frequency to its secondary winding. The aim of this work is to
quantify the influence of the inductive VTs on measured
transient voltage waveforms.