Chipset measures complete set of 3-phase AC power parameters

January 06, 2015 // By Graham Prophet
Analog Devices has posted details of a chipset specifically designed for measuring 3-phase electrical energy, using shunts as current sensors. The chipset comprises the ADE7978, the ADE7933/ADE7932, and ADE7923.

The ADE7933/ADE7932 are isolated, 3-channel sigma-delta analogue-to-digital converters (Σ-Δ ADCs) for polyphase energy metering applications that use shunt current sensors. The ADE7923 is a nonisolated, 3-channel Σ-Δ ADC for the neutral line that uses a shunt current sensor. The ADE7932 features two 24-bit ADCs, and the ADE7933 and ADE7923 feature three 24-bit ADCs.

One channel is dedicated to measuring the voltage across the shunt when a shunt is used for current sensing. This channel provides a signal-to-noise ratio (SNR) of 67 dB over a 3.3 kHz signal bandwidth. Up to two additional channels are dedicated to measuring voltages, which are usually sensed using resistor dividers.

The unused voltage channels on the neutral ADE7923 can be used for auxiliary voltage measurements. These channels provide an SNR of 75 dB over a 3.3 kHz signal bandwidth. One voltage channel can be used to measure the temperature of the die via an internal sensor.

The ADE7933 and ADE7923 include three channels: one current channel and two voltage channels. The ADE7932 includes one current channel and one voltage channel, but is otherwise identical to the ADE7933.

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