ADE9078 Analog Front-End for Energy Metering

By Analog Devices Inc 54

ADE9078 Analog Front-End for Energy Metering

Analog Devices' ADE9078 is a highly accurate, fully integrated energy-metering device. Interfacing with both current transformer (CT) and Rogowski coil sensors, the ADE9078 enables users to develop a 3-phase metrology platform, which achieves high performance for Class 1 up to Class 0.2 meters. The ADE9078 integrates seven high performances ADCs and a flexible DSP core. An integrated high-end reference ensures low drift over temperature with a combined drift of less than ±25 ppm/°C maximum per channel, each of which includes a programmable gain amplifier (PGA) and ADC.

The ADE9078 offers an integrated flexible waveform buffer that stores samples at a fixed data rate or a sampling rate that varies based on line frequency to ensure 64 points per line cycle. These two options make it easy to implement harmonic analysis in an external processor according to IEC 61000-4-7. Two power modes are provided to enable detection of meter tampering: PSM2 uses a low power comparator to compare current channels to a threshold and indicates whether it is exceeded on the IRQ0 and IRQ1 outputs; PSM1 enables fast measurement of current and voltage rms (xVRMS and xIRMS), active power, and VAR during a tamper.

The ADE9078 allows advanced and highly accurate energy measurements, enabling one platform to cover a wide range of meters, through a combination of various high-end metrology features and superior analog performance.

Features
  • Power quality measurements
    • Line frequency: 1 measurement per phase
    • Zero crossing detection, zero-crossing timeout
    • Phase angle measurements
  • High performance analog-to-digital converters (ADCs)
    • 101 dB signal-to-noise ratio (SNR)
    • 10,000:1 dynamic range
    • Wide input range: ±1 V, 0.707 VRMS full scale
    • Differential inputs
  • Flexible waveform buffer
    • Able to resample waveform to ensure 64 points per line cycle for ease of external harmonic analysis
    • Events can trigger waveform storage
    • Simplifies data collection for IEC 61000-4-7 harmonic analysis
  • ±25 ppm/°C maximum channel temperature drift (including ADC, internal VREF, and PGA drift) enabling Class 0.2 meters with standard external components
  • Supports current transformers (CTs) and Rogowski coil (di/dt) sensors
    • Multiple range phase/gain compensation for CTs
    • Digital integrator for Rogowski coils
  • Advanced metrology feature set
    • Total active power, volt-amperes reactive (VAR), volt-amperes (VA), watthour, VAR-hour, and VA-hour
    • Fundamental VAR and VAR-hour
    • Current and voltage rms per phase (xIRMS, xVRMS)
    • Supports active energy standards: IEC 62053-21, IEC 62053-22; EN50470-3; OIML R46, ANSI C12.20
    • Supports reactive energy standards: IEC 62053-23, IEC 62053-4
    • High speed communication port
    • 10 MHz serial peripheral interface (SPI)

Applications

  • Energy systems monitoring
  • Polyphase meters
  • Power quality monitoring
  • Protective devices

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