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If your power monitoring system captures events beyond your comprehension, improper settings may be to blame.
The waveform trigger feature in GMC-I’s HDPQ Series Power Quality Analyzers is a powerful tool for detecting step load changes, negative transients, harmonics, and other intermittent fast variations in voltage or current that may impact power systems. This trigger continuously monitors cyclical changes in voltage and/or current. Whether your power is "clean" or "dirty," if it’s stable and unchanging, the waveform trigger won’t activate. It scans each AC cycle for potentially harmful fluctuations—but if misconfigured, it can also generate unnecessary triggers.
Distortions or load variations (e.g., notches, load shifts, SCR commutation) may cause such changes. These aren’t necessarily faults, but to a poorly tuned monitoring system, they might appear as such.
The result? Excessive trigger events and bloated data files. You’re drowning in noise when what you need is clarity.
This article explains how HDPQ’s waveform triggers work, why false triggers occur, and how to adjust settings to focus only on critical events.
Two Trigger Types Explained
The HDPQ Series offers two primary methods for detecting waveform anomalies:
1. Waveform Difference Trigger
The more sensitive of the two.
Splits each 50/60 Hz AC cycle into smaller windows (e.g., 10 windows at 10% each).
Compares each segment of the current cycle to the same segment in the previous cycle.
Triggers if the difference exceeds a user-defined threshold.
Best for: Short-duration mid-cycle changes (e.g., sags, micro-transients).
Risk: Over-sensitivity in consistently distorted environments if not calibrated properly.
2. RMS Deviation Trigger
Takes a broader approach.
Compares entire waveform cycles (sample-by-sample subtraction).
Triggers if the cumulative deviation exceeds a set threshold.
Best for: Sustained changes (e.g., voltage dips/swells) rather than transient distortions.
Both methods are useful, but the Waveform Difference Trigger may fire repeatedly if misconfigured in systems with inherent distortion.
Pre-Monitoring Checklist
Before starting:
Inspect waveforms in oscilloscope mode to observe real-time voltage/current under load.
Stable waveforms? Default settings usually suffice.
Variable/high-harmonic waveforms? Adjust settings before deployment.
Pay special attention to current—it often fluctuates significantly with load changes.
Neglecting this risks collecting low-value data.
How to Optimize Settings
In the HDPQ Setup Wizard:
Navigate to Trigger Limits > Set Waveform Transients.
Adjust Amplitude Threshold to reflect realistic system conditions.
Use "Set ABC Uniform" for consistent three-phase thresholds.
For distortions unrelated to your goals (e.g., inherent system noise), disable the trigger entirely.
A Case Study in Dran-View
An HDPQ unit recorded repeated events due to a 66.3V peak-to-peak voltage distortion. The original amplitude threshold (48.0V) was too low for this environment. Adjusting it reduced false triggers while preserving relevant data.
Pro Tip: Use Dran-View 7’s zoom/measurement tools to validate changes.
Pre-Deployment Best Practices
Fine-tuning trigger thresholds lets the HDPQ adapt to any environment, delivering clean, actionable data. Before each deployment:
✅ Check waveform conditions in oscilloscope mode.
✅ Adjust trigger thresholds accordingly.
✅ Disable irrelevant triggers.
Result: Less noise, fewer wasted hours reviewing non-events, and higher confidence in shared data.
Need a second opinion on your setup?
Contact your local GMC-I sales representative for expert guidance.
This version emphasizes practical steps, clear comparisons between trigger types, and actionable advice—tailored for engineers seeking to optimize their power quality analysis. Let me know if you'd like to highlight any specific features further!
