Abstract
Contactless measurements represent the desirable solution in many contexts, where minimal cabling is required or, in general, cabling is not possible. This paper presents a new contactless voltage sensor for low voltage power systems. It is based on a contactless capacitive probe, which surrounds the power cable. It has two concentric electrodes insulated by a shield. A low power analog conditioning circuit evaluates the power line voltage by measuring the current in one of the capacitances of the probe. All the single stages of the circuit have been designed by using low-power rail-to-rail operational amplifiers, supplied at 3.3 V, in order to minimize the power absorption. The sensor has been characterized in various conditions, with sine waves and distorted signals, varying the frequency and the harmonic distortion. The influence of the current, flowing into the power cable, on the voltage measurement has been evaluated too. It shows a good accuracy (lower than 0.3%) from 100 V to 300 V, with a power consumption less than 5 mW.
Highlights
The demand of smart measurement systems and innovative sensors based on Internet of Things (IoT) methods has increased thanks to advances in the fields of low power electronics, information technology, and communications [1]
The NI 9225 was used to acquire the output of the VAT, that is, voltage sensed by the CVS, whereas the NI 9239 was used to acquire three signals provided by the CVS, that are VLP, VRP, and VDC as in Equations (5) and (6), and the output voltage of the current sensor
This paper presents a new low powercontactless contactlessvoltage voltagesensor sensorfor forlow lowvoltage voltagepower powersystems
Summary
The demand of smart measurement systems and innovative sensors based on Internet of Things (IoT) methods has increased thanks to advances in the fields of low power electronics, information technology, and communications [1]. In order to allow the widespread diffusion of IoT devices, they must be simple to use and to install. In this context, measuring devices adopting contactless sensing principles represent enabling technologies for the IoT. 2 ofthe widespread diffusion of the solutions Starting from these considerations, in this paper, a new new power power line line contactless contactless voltage voltage sensor. A similar approach is presented in Reference [19]; it makes use of non-linear devices and phase shifters, which have power consumption not suitable for IoT applications and, compromise compromisethe theaccuracy accuracyof ofthe thewhole wholedevice.
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