Solution for partial discharge detection based on analog-to-digital converter GX7793 and voltage feedback operational amplifier GX2354, replacing AD7793/OPA2354

Partial discharge detection sensors have built a digital perception network for equipment health management in smart grids through innovative technological means. Partial discharge detection is a small-scale discharge phenomenon that occurs inside or on the surface of high-voltage power equipment insulation, and is an early key sign of insulation aging or defects. By using techniques such as ultrasound, high frequency, ultra-high frequency, and transient ground voltage for detection, it is easy to detect insulation defects early, evaluate equipment status, and predict lifespan.

Principle: Through a multi-dimensional signal capture mechanism, the partial discharge detection sensor adopts a composite detection technology to achieve full frequency coverage of the discharge signal. Ultra high frequency sensors can capture electromagnetic waves generated by air gap discharge inside the device, while ultrasonic sensors identify surface discharge characteristics by detecting sound wave signals.

The GXSC 24 bit analog-to-digital converter GX7793 supports ultra-low frequency band accuracy (INL ± 0.001%) from 0.1Hz to 1kHz, suitable for transformer vibration harmonic analysis. The GX2354 amplifier has nanosecond level pulse response capability, which can match the frequency band requirements of HFCT sensors above 100MHz.

The GX7793 contains three differential analog inputs and integrates an on-chip low-noise instrumentation amplifier, allowing for direct input of small signals. The GX7793 can operate with either an internal clock or an external clock, and the output data rate can be set through software programming, ranging from 4.17Hz to 940Hz. The ultra-low power consumption characteristics of this chip are very suitable for power frequency harmonic analysis.

The GX2354 amplifier has stable unit gain and can output high current, with a differential gain of 0.02% and a differential phase of 0.09 °. The static current is only 5mA per channel. This operational amplifier is optimized for single or dual power supply operation ranging from as low as 2.7V (± 1.35V) to as high as 5.5V (± 2.75V), with a common mode input range beyond the power supply range. The output swing of the power rail is within 100mV, thus supporting a wide dynamic range. Thanks to the patented high-pressure swing rate technology, the response speed of large signals is faster and the convergence is more stable.