The Design and Characterization of a Prototype Wideband Voltage Sensor Based on a Resistive Divider
Laboratorio Central Oficial de Electrotecnia (LCOE), Fundación para el Fomento de la Innovación Industrial (FFII), c/Eric Kandel, 1, 28906 Getafe, Madrid, Spain
Author to whom correspondence should be addressed.
Sensors 2017, 17(11), 2657; https://doi.org/10.3390/s17112657
Received: 19 August 2017 / Revised: 6 October 2017 / Accepted: 12 October 2017 / Published: 17 November 2017
(This article belongs to the Section Physical Sensors)
The most important advantage of voltage dividers over traditional voltage transformers is that voltage dividers do not have an iron core with non-linear hysteresis characteristics. The voltage dividers have a linear behavior with respect to over-voltages and a flat frequency response larger frequency range. The weak point of a voltage divider is the influence of external high-voltage (HV) and earth parts in its vicinity. Electrical fields arising from high voltages in neighboring phases and from ground conductors and structures are one of their main sources for systematic measurement errors. This paper describes a shielding voltage divider for a 24 kV medium voltage network insulated in SF6 composed of two resistive-capacitive dividers, one integrated within the other, achieving a flat frequency response up to 10 kHz for ratio error and up to 5 kHz for phase displacement error. The metal shielding improves its immunity against electric and magnetic fields. The characterization performed on the built-in voltage sensor shows an accuracy class of 0.2 for a frequency range from 20 Hz to 5 kHz and a class of 0.5 for 1 Hz up to 20 Hz. A low temperature effect is also achieved for operation conditions of MV power grids.