Characterization of DC Current Sensors With AC Distortion for Railway Applications

Abstract

To assess the reliability of dc energy measurement equipment on-board trains, a setup was developed to characterize current transducers under realistic operating conditions. The operating principle is based on a current ratio measurement technique. The reference sensor is a high-precision zero-flux current transducer in combination with a broadband highprecision current shunt. The influence of ac distortion on this reference sensor was found to be within a few parts in 10 6 using an initial version of the setup, in which ac distortion was applied through a separate winding. A revised version of the setup employs a programmable electronic load to apply dynamic currents up to 600 A. The setup was used to characterize a 100 μ high-current shunt resistor. The effect of dissipative heating on the dc transresistance error was around 0.03 %, with a settling time of about half an hour. The short-term intrinsic current dependence was also around 0.03 %. The effect of ac distortion was within a few parts in 10 6 . The intrinsic current dependence and the onset of the heating effect were also observed when exposing the sensor to a dynamic current profile that was recorded during a trip between two successive underground train stations on Metro de Madrid. These results demonstrate that the setup described in this paper is very effective for characterizing dc current sensors for practical railway applications. Future work will concentrate on even more demanding current signals, such as chopped signals, and on other types of sensors and measurement systems.

Testing of DC Electricity Meters with Broadband Conducted Electromagnetic Disturbances

“…The output current of the DC power source can be modified by adjusting the resistance of the programmable load to introduce AC distortions into the DC signal. This approach was used before to calibrate sensors for railway applications at DC currents up to 600 A with AC distortion signals containing frequency components up to a few kilohertz [26]. Although in principle the electronic load can change its load resistance with frequencies up to 50 kHz, slewrate or other bandwidth limitations of the power source seem to limit the frequency range to a few kilohertz [27].…”

“…Therefore, the zero-flux device can be calibrated and characterized by driving a high DC current through one conductor in a closed circuit while simultaneously applying a high-frequency AC distortion using a separate closed circuit while sensing both respective conductors. This principle was exploited for instance to characterize DC current sensors with AC distortions for railway applications [26]. This way, the zero-flux device is calibrated and characterized in a way resembling its use in practice.…”

Calibrating Sensors to Measure Braking Chopper Currents in DC Traction Units

“…The ratio of the output voltages of the two transducers is measured using two high-precision digital voltmeters with a sampling rate of 50 kS/s. The voltage ratio can be determined with an accuracy of better than two parts in 10 6 [1,2].…”

“…In this paper preliminary results of the development of a reference setup are presented for the calibration of current transducers using chopped high-current waveforms for braking chopper applications in DC traction units. The setup is based on a current ratio measurement system [1] that was modified for the characterization of DC current sensors in the presence of AC distortion developed for railway applications [2].…”

Measurement of the DC current based on magnetic fluids with an orthogonal magnetic field

“…With the development of photovoltaic power generation, DC power transmission, [1][2][3] DC distribution, railway application, 4 as well as for further improving the efficiency of DC/AC energy conversion, 5 DC power generation technology has received intensive attention recently. At the same time, DC current measurement is becoming more important.…”