Measurement of Lightning Currents Using a Combination of Rogowski Coils and B-Dot Sensors

Abstract

Abstract:The paper presents laboratory tests for the characterization of commercial Rogowski coils and a specially designed B-Dot sensor for the measurement of lightning currents on the Säntis telecommunications tower in Switzerland. In order to overcome the limited high frequency response of the Rogowski coils, we propose to use magnetic loops located very close to the tower. We introduce the design of a B-Dot sensor based on improvements proposed by C. E. Baum, in which the inductance is lowered by extending the vertical dimension of the loop, with the overall effect of extending the operating frequency range. To overcome the integrating behavior of the B-Dot loop when connected to lowimpedance loads (such as 50 Ohm), an arrangement of 100-Ohm-impedance cables connected across conicaltransmission-line gaps is used. The designed sensor is characterized by an upper frequency cutoff of 20 MHz and a 50 Ohm matched termination. Simulation results and laboratory tests carried out in the high voltage laboratories of the EPFL and Montena EMC show the effectiveness of the simultaneous use of Rogowski coils and B-Dot sensors for the measurement of lightning currents.

Statistical Distributions of Lightning Currents Associated With Upward Negative Flashes Based on the Data Collected at the Säntis (EMC) Tower in 2010 and 2011

“…The Säntis station has been instrumented using advanced and modern equipment including remote monitoring and control capabilities for an accurate measurement of lightning current parameters [13], [15]. The lightning current is measured at two 0885-8977/$31.00 © 2013 IEEE different heights, 24 m and 82 m. At the lower height, we installed two Rogowski coils with different sensitivities, each one with its analog integrator used to obtain the current waveform.…”

“…The second sensor placed at that height is a specially-designed multi-gap magnetic loop (B-Dot) sensor. It has been specifically developed to measure the lightning current derivative [16]. The analog outputs of the sensors are relayed to a digitizing system by means of analog-to-digital-digital-to-analog 12-bit optical links characterized by an overall bandwidth from dc to 25 MHz.…”

“…The maximum measurable current level with the PEM Rogowski coils is 120 kA and the maximum measurable current derivative with the B-Dot sensor is 400 kA/ìs. The PEM Rogowski coil located at 82 m is characterized by a frequency response ranging from 50 mHz to 2.4 MHz, while the upper frequency limit of the B-Dot sensor is about 20 MHz (for more details, see [16]). The measurement window for each flash is 1.2 s with a pre-trigger delay of 0.25 s and a sampling frequency of 100 MHz.…”

“…The server and the front-end station are connected to the Internet over a router and a standard DSL link, allowing remote maintenance, monitoring, and control of the overall measurement chain. More details on the installed measurement system can be found in [13], [16].…”

Lightning Interactions with Humans and Lifelines

“…Lightning currents measurement experiments with Rogowski coil and B-dot sensors shows upper frequency cut off at 20MHz with 50Ω matching terminations. A 10 m long PEM CWT 600×/11700 type Rogowski coil can measure up to 1MHz with peak di/dt of 150 kA/µs [63]. A comparative study of Hall, magnetic and optical current sensors proved superior performance of fiber optic current transducers [64].…”