# KNOWLEDGE BASE: INDUSTRIAL POWER QUALITY

## 🔌 The Threat of Harmonic Pollution
In modern industrial plants, the widespread use of non-linear loads (Variable Frequency Drives, rectifiers, switching power supplies) introduces current harmonics ($I_h$) into the electrical distribution system. 
This distortion pollutes the utility grid, resulting in:
- Premature aging and overheating of distribution transformers.
- Nuisance tripping of circuit breakers.
- Severe voltage sags, power surges, and utility penalties.

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## 📋 Compliance & Standards (IEEE 519-2022)
**IEEE 519** establishes strict limits for electrical grid harmonic distortion at the Point of Common Coupling (PCC):
1. **Voltage Distortion (THDV)**:
   - Must remain **under 5.0%** for buses rated $\le 69\text{ kV}$.
2. **Current Distortion (THDI)**:
   - Must remain **under 8.0%** (scales based on short-circuit ratios).

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## ⚡ Active Harmonic Filter (AHF) Sizing & Waveform Correction
Orbit AI Power Quality continuously monitors phase-to-phase waveforms via sub-meter analyzers and automates AHF sizing:
- **Phase Vector Injection**: The AHF acts as a dynamic current source, injecting equal and opposite phase harmonic current vectors to cancel out non-linear distortions.
- **kVAR Sizing Equation**:
  $$Q_{AHF} = \sqrt{S^2 - P^2 - Q_{fundamental}^2}$$
- **Post-Mitigation Waveform**: Suppression of 5th, 7th, and 11th order currents restores the jagged, distorted current wave back to a smooth, nominal sinusoidal curve, ensuring perfect IEEE 519 compliance.