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MSO5000 Power Analyzer — Technical Overview

Project Title: Real-Time Power Analyzer using Rigol MSO5000
Author: Aether Research Institute (ariDev1)
Date: 2025-07-26
Repository: GitHub/MSO5000_liveview

Purpose

This project transforms a Rigol MSO5000 oscilloscope into a real-time power analyzer capable of high-resolution electrical measurements including power, energy, and phase relationships.

It is designed to match or exceed the functionality of commercial power meters by leveraging open software and SCPI-based waveform extraction.

⚙System Overview

The system is composed of:

  • 🖥️ A Python-based GUI using Tkinter and matplotlib
  • 🔌 Live waveform acquisition via SCPI (VISA)
  • 🧮 Real-time computation of:
  • Active Power (P)
  • Reactive Power (Q)
  • Apparent Power (S)
  • Power Factor (PF) and phase angle
  • 📈 Live PQ plotting with quadrant display
  • 🧪 Calibration via expected power or correction factor

Methodology

1. Waveform Extraction

Voltage and current waveforms are acquired from the oscilloscope using SCPI commands like:

:WAV:SOUR CHAN2
:WAV:MODE NORM
:WAV:DATA?

The data is rescaled and processed into NumPy arrays for numerical computation.

2. Power Calculation

Given voltage \( v(t) \) and current \( i(t) \), the following are computed:

  • Vrms = \( \sqrt{\frac{1}{N} \sum v_i^2} \)
  • Irms = \( \sqrt{\frac{1}{N} \sum i_i^2} \)
  • P = \( \frac{1}{N} \sum v_i \cdot i_i \)
  • S = \( \text{Vrms} \cdot \text{Irms} \)
  • Q = \( \sqrt{S^2 - P^2} \)
  • PF = \( \frac{P}{S} \)

Optional: DC offset can be removed from each waveform before RMS/P computation.

3. Phase Detection

The phase shift between voltage and current is calculated using cross-correlation to identify the time delay between the two waveforms. This delay is then converted to a phase angle in degrees, based on the fundamental waveform frequency, yielding an accurate measure of the phase relationship.

📊 Visualization Features

  • Real-time PQ Vector Plot
  • Live quadrant tracking
  • Time-based energy accumulation:
  • Real energy (Wh)
  • Apparent energy (VAh)
  • Reactive energy (VARh)

Calibration Options

Method Description
Correction Factor Manually entered scaling applied to current input
Auto Calibration User enters expected power value; correction factor is calculated automatically
Unit Detection Scope’s CHANx:UNIT? is queried to determine whether input is in V or A

Data Logging

  • Power logs are stored as CSV files under /oszi_csv/
  • Logs include timestamp, P, Q, S, PF, Vrms, Irms, and energy metrics
  • Last session summary plot saved as PNG

Error Handling and Stability

  • Prevents power analysis during long-term logging
  • Detects non-finite results and skips invalid reads
  • Tracks DC offset toggle status
  • Scope disconnection is handled gracefully

What You Gain

  • Fully open and transparent power analyzer
  • Reproducible results
  • Custom scaling, probing, and filtering logic
  • Scientific accuracy without vendor lock-in

License

This software is released under an open-source license. Use at your own risk. Accuracy depends on oscilloscope bandwidth, probe calibration, and SCPI reliability.