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Harmonics

Analyze harmonic spectrum and total harmonic distortion.

What This Tab Does

The Harmonics tab breaks down any voltage or current waveform into its constituent frequency components. It computes the magnitude of each harmonic order (up to the 25th by default), displays the spectrum as a bar chart, and calculates Total Harmonic Distortion (THD) along with diagnostic indicators for CT saturation, transformer inrush, and overexcitation. This tab requires sign-in.

Harmonic analysis is essential for identifying waveform distortion, verifying relay restraint behavior, and assessing power quality. Use the playback slider or move the cursor to see how the harmonic content evolves over time.

1Channel:IA2

SpectrumTrend

3t =0.045s

CT Saturation

High THD

Normal

% of Fundamental

100%

7.1%

4.7%

1.8%

5.2%

0.9%

IEEE 519 Limit

Harmonic Order

THD

5.2%

K-Factor

3.1

Crest

1.42

Fund.

230.1V

Harmonic Detail

Order	Peak	RMS	Angle	% Fund.	% RMS	Limit
1F	325.483	230.131	0.0°	---	97.2%	—
2	23.109	16.342	45.2°	7.1%	6.9%	5.0%
3	15.281	10.805	90.1°	4.7%	4.6%	5.0%
4	5.852	4.138	12.5°	1.8%	1.7%	5.0%
5	16.935	11.974	-30.4°	5.2%	5.1%	5.0%
6	2.930	2.072	155.3°	0.9%	0.9%	5.0%

Channel Overview

Channel	THD %	Fund	K-Fac	CF	H3	H5
IA	5.2%	230.1 A	3.1	1.42	4.7%	5.2%
IB	3.1%	228.4 A	2.0	1.41	2.1%	1.8%
IC	4.5%	231.2 A	2.8	1.40	3.5%	3.2%
VA	1.8%	66.2k V	1.2	1.41	1.2%	0.8%
VB	1.5%	65.8k V	1.1	1.41	0.9%	0.6%

Channel selector — Dropdown to pick which analog channel to analyze. Defaults to IA or VA if available.

Spectrum / Trend toggle — Switch between bar chart (snapshot at cursor time) and line chart (THD, H2/H1%, H5/H1% over time).

Time display — Shows the current cursor time being analyzed. Updates when the cursor moves on the waveform viewer.

Diagnostics strip — Colored severity badges auto-classified from harmonic content: info (green), warning (amber), alert (red). Shows CT Saturation, Transformer Inrush, Overexcitation, High THD, IEEE 519 Violation, or Normal.

Chart area — Spectrum mode: bar chart with % labels, IEEE 519 limit line (red dashed), non-compliant bars turn red. Trend mode: THD%, H2/H1%, H5/H1% over time with cursor line; click to set cursor.

Metrics cards — 2×2 grid: THD (%), K-Factor, Crest Factor, Fundamental magnitude. Color-coded severity bars — green (normal), amber (warning), red (alert).

Harmonic detail table — Per-order breakdown: Order, Peak, RMS, Angle, % Fundamental, % True RMS, IEEE 519 limit. Fundamental row highlighted; non-compliant rows red-tinted.

Channel overview table — All channels at once: THD%, Fundamental, K-Factor, Crest Factor, H3, H5. Click any row to switch channel. Selected row is highlighted.

Time Playback

The playback slider at the top of the tab lets you animate the harmonic spectrum through time. Press Play to watch the bar chart, THD values, metrics cards, and diagnostic badges update in real time as the recording progresses. This is especially useful for observing transient harmonic phenomena — for example, watching 2nd harmonic content decay during transformer inrush, or seeing THD spike at the instant of CT saturation.

Drag the slider thumb to scrub to any specific moment. When dual cursors (A/B) are placed on the waveform, their positions appear as draggable markers on the slider, and Jump to A/B buttons let you snap between the two points with one click.

The Spectrum view (animated via the slider) shows harmonic content at a single point in time. For a full timeline overview, switch to the Trend view which shows how THD and key harmonic ratios change across the entire recording.

Time Playback Slider

123

A4B

545 / 200 ms61x

7Jump to:AB

1Play / Pause — animate through the recording. Phasors, power, harmonics, and readout values update in real time during playback.

2Reset — jump back to the start of the recording.

3Slider track — drag the thumb to scrub to any point in the recording. The filled portion shows current position.

4A/B cursor markers — when dual cursors are placed on the waveform, their positions appear as draggable markers (blue for A, orange for B). Drag a marker to reposition that cursor.

5Time readout — current playback position and total recording duration in milliseconds.

6Speed control — click to cycle through presets (0.5×, 1×, 2×, 4×, 8×). Double-click to type a custom speed. At 1× speed, one power cycle takes one second of wall time.

7Jump to A / B — snap the slider position to cursor A or cursor B. Only visible when both dual cursors are placed.

Reading the Harmonic Bar Chart

The bar chart shows the magnitude of each harmonic order as a percentage of the fundamental (1st harmonic). The tallest bar is always the fundamental at 100%. Other bars show how much energy is present at multiples of the fundamental frequency.

Clean waveform: Only the fundamental bar is significant; all other bars are near zero. THD is low (below 5%).
CT saturation: Elevated even harmonics (2nd, 4th) with high THD. Look for the 2nd harmonic above 10-15% combined with overall waveform asymmetry.
Transformer inrush: Very high 2nd harmonic (30-70% of fundamental) with moderate 3rd harmonic. The magnitude decays over several cycles.
Overexcitation: High odd harmonics (3rd, 5th) with a relatively low 2nd harmonic. The 5th harmonic above 25% is a strong indicator.

What THD Means

Total Harmonic Distortion (THD) is a single percentage that summarizes how distorted a waveform is compared to a pure sinusoid. A THD of 0% means a perfect sine wave with no harmonics. A THD of 5% means the harmonic content is 5% of the fundamental magnitude.

In power quality standards (IEEE 519), voltage THD below 5% is considered acceptable for systems below 69 kV. During fault recordings, THD may be elevated due to CT saturation rather than actual power quality issues -- context matters when interpreting THD values.

Automatic Diagnostics

Detego automatically classifies harmonic content and displays colored badges in the Harmonics tab:

Badge	What It Means	Severity
Transformer Inrush	2nd harmonic exceeds 15% of fundamental on a current channel	Warning
CT Saturation	2nd harmonic above 10% and even harmonic ratio above 30% on current	Alert
Overexcitation	5th harmonic above 25% and more than twice the 2nd harmonic	Warning
High THD	THD exceeds 5%	Warning
IEEE 519 Violation	Any individual harmonic or THD exceeds the IEEE 519 limit for the voltage class	Alert

Harmonic Trend View

The Trend view shows how THD%, H2/H1%, and H5/H1% change over time across the entire recording. This is useful for identifying transient phenomena: a decaying 2nd harmonic ratio confirms transformer inrush, while a sudden THD spike at fault inception points to CT saturation. The trend is computed one cycle at a time and capped at 500 data points for performance. For animated single-point analysis, use the Spectrum view with the playback slider instead.

Per-Harmonic Detail Table

The detail table shows the following for each harmonic order:

Column	Description
Order	Harmonic order (0 = DC, 1 = fundamental, 2 = 2nd, ...)
Frequency	Harmonic frequency in Hz
Magnitude	RMS magnitude (in the channel unit)
Percentage	Percentage of the fundamental magnitude
% True RMS	Percentage of the true RMS value (useful when the fundamental is small)
Angle	Phase angle in degrees

Tips

Press Play on the slider to animate the harmonic spectrum through the recording. Watch for the 2nd harmonic spike at fault inception (CT saturation) or during transformer energization (inrush).
Use the Jump to A/B buttons to compare harmonic content at two different moments — for example, pre-fault steady state (A) versus peak fault current (B).
Use the Trend view for a full-recording overview, and the Spectrum view with the playback slider for detailed single-point analysis.
For power quality assessment, scrub the slider to a steady-state period (not during a fault) and compare THD against IEEE 519 limits.
Harmonics above the Nyquist frequency (half the sample rate) are automatically excluded. If you need higher-order harmonics, ensure your recording has a sufficiently high sample rate.

How it works

For the DFT computation, windowing strategy, THD formula, K-factor, and detection algorithms, see Theory: Harmonic Analysis.

PreviousFault ID NextReadout

Loading documentation...

Harmonics

Analyze harmonic spectrum and total harmonic distortion.

What This Tab Does

1Channel:IA2

SpectrumTrend

3t =0.045s

CT Saturation

High THD

Normal

% of Fundamental

100%

7.1%

4.7%

1.8%

5.2%

0.9%

IEEE 519 Limit

Harmonic Order

THD

5.2%

K-Factor

3.1

Crest

1.42

Fund.

230.1V

Harmonic Detail

Order	Peak	RMS	Angle	% Fund.	% RMS	Limit
1F	325.483	230.131	0.0°	---	97.2%	—
2	23.109	16.342	45.2°	7.1%	6.9%	5.0%
3	15.281	10.805	90.1°	4.7%	4.6%	5.0%
4	5.852	4.138	12.5°	1.8%	1.7%	5.0%
5	16.935	11.974	-30.4°	5.2%	5.1%	5.0%
6	2.930	2.072	155.3°	0.9%	0.9%	5.0%

Channel Overview

Channel	THD %	Fund	K-Fac	CF	H3	H5
IA	5.2%	230.1 A	3.1	1.42	4.7%	5.2%
IB	3.1%	228.4 A	2.0	1.41	2.1%	1.8%
IC	4.5%	231.2 A	2.8	1.40	3.5%	3.2%
VA	1.8%	66.2k V	1.2	1.41	1.2%	0.8%
VB	1.5%	65.8k V	1.1	1.41	0.9%	0.6%

Channel selector — Dropdown to pick which analog channel to analyze. Defaults to IA or VA if available.

Spectrum / Trend toggle — Switch between bar chart (snapshot at cursor time) and line chart (THD, H2/H1%, H5/H1% over time).

Time display — Shows the current cursor time being analyzed. Updates when the cursor moves on the waveform viewer.

Chart area — Spectrum mode: bar chart with % labels, IEEE 519 limit line (red dashed), non-compliant bars turn red. Trend mode: THD%, H2/H1%, H5/H1% over time with cursor line; click to set cursor.

Metrics cards — 2×2 grid: THD (%), K-Factor, Crest Factor, Fundamental magnitude. Color-coded severity bars — green (normal), amber (warning), red (alert).

Harmonic detail table — Per-order breakdown: Order, Peak, RMS, Angle, % Fundamental, % True RMS, IEEE 519 limit. Fundamental row highlighted; non-compliant rows red-tinted.

Channel overview table — All channels at once: THD%, Fundamental, K-Factor, Crest Factor, H3, H5. Click any row to switch channel. Selected row is highlighted.

Time Playback

Time Playback Slider

123

A4B

545 / 200 ms61x

7Jump to:AB

1Play / Pause — animate through the recording. Phasors, power, harmonics, and readout values update in real time during playback.

2Reset — jump back to the start of the recording.

3Slider track — drag the thumb to scrub to any point in the recording. The filled portion shows current position.

4A/B cursor markers — when dual cursors are placed on the waveform, their positions appear as draggable markers (blue for A, orange for B). Drag a marker to reposition that cursor.

5Time readout — current playback position and total recording duration in milliseconds.

6Speed control — click to cycle through presets (0.5×, 1×, 2×, 4×, 8×). Double-click to type a custom speed. At 1× speed, one power cycle takes one second of wall time.

7Jump to A / B — snap the slider position to cursor A or cursor B. Only visible when both dual cursors are placed.

Reading the Harmonic Bar Chart

Clean waveform: Only the fundamental bar is significant; all other bars are near zero. THD is low (below 5%).
CT saturation: Elevated even harmonics (2nd, 4th) with high THD. Look for the 2nd harmonic above 10-15% combined with overall waveform asymmetry.
Transformer inrush: Very high 2nd harmonic (30-70% of fundamental) with moderate 3rd harmonic. The magnitude decays over several cycles.
Overexcitation: High odd harmonics (3rd, 5th) with a relatively low 2nd harmonic. The 5th harmonic above 25% is a strong indicator.

What THD Means

Automatic Diagnostics

Detego automatically classifies harmonic content and displays colored badges in the Harmonics tab:

Badge	What It Means	Severity
Transformer Inrush	2nd harmonic exceeds 15% of fundamental on a current channel	Warning
CT Saturation	2nd harmonic above 10% and even harmonic ratio above 30% on current	Alert
Overexcitation	5th harmonic above 25% and more than twice the 2nd harmonic	Warning
High THD	THD exceeds 5%	Warning
IEEE 519 Violation	Any individual harmonic or THD exceeds the IEEE 519 limit for the voltage class	Alert

Harmonic Trend View

Per-Harmonic Detail Table

The detail table shows the following for each harmonic order:

Column	Description
Order	Harmonic order (0 = DC, 1 = fundamental, 2 = 2nd, ...)
Frequency	Harmonic frequency in Hz
Magnitude	RMS magnitude (in the channel unit)
Percentage	Percentage of the fundamental magnitude
% True RMS	Percentage of the true RMS value (useful when the fundamental is small)
Angle	Phase angle in degrees

Tips

Press Play on the slider to animate the harmonic spectrum through the recording. Watch for the 2nd harmonic spike at fault inception (CT saturation) or during transformer energization (inrush).
Use the Jump to A/B buttons to compare harmonic content at two different moments — for example, pre-fault steady state (A) versus peak fault current (B).
Use the Trend view for a full-recording overview, and the Spectrum view with the playback slider for detailed single-point analysis.
For power quality assessment, scrub the slider to a steady-state period (not during a fault) and compare THD against IEEE 519 limits.
Harmonics above the Nyquist frequency (half the sample rate) are automatically excluded. If you need higher-order harmonics, ensure your recording has a sufficiently high sample rate.

How it works

For the DFT computation, windowing strategy, THD formula, K-factor, and detection algorithms, see Theory: Harmonic Analysis.

PreviousFault ID NextReadout