We report a novel battery-less wireless current sensor node without
an analog to digital converter (ADC). If a capacitor is charged using a current
transformer (CT) and a rectifying circuit, the charging time depends on the
current flowing through a power line. In the case that the node transmits data
every time when voltage of the capacitor exceeds a threshold voltage, we can
indirectly measure the current by measuring the transmission intervals. In this
method, the circuit of the node can be simplified and power consumption for the
wireless transmission can be decreased because the measured current data does
not need to be included in the transmitted packet. However, the measurable
range is about single digit because the transmission interval decreases
suddenly as the current increases. In this work, we have ex- panded
the range using one CT, one wireless transmission module, and two charging
circuits that include different load resistors connected in series. The results
indicated that the measurable range was from 0.5 A to 50 A.
Cite this paper
H. Okada and T. Itoh, "Development of Battery-Less Wireless Current Sensor Node Utilizing Charging Time of Capacitors with Wide Measurement Range," Wireless Sensor Network
, Vol. 5 No. 11, 2013, pp. 223-228. doi: 10.4236/wsn.2013.511026
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 H. Okada and T. Itoh, “Battery-Less Wireless Current Sensor Node Utilizing the Dependence of Charging Time of a Capacitor on the Current Flowing through a Power Line,” IEICE Electronics Express, Vol. 10, No. 12, 2013. http://dx.doi.org/10.1587/elex.10.20130308
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 Linear technology: datasheet of LTC1540, p. 5.
 Silicon laboratories: datasheets of C8051F93x-C8051F92x, p. 46.
 Nordic semiconductor: datasheets of nRF24L01, p. 13.