Duval Triangle+

Overview

When to use it

Use Duval Triangle+ when you need to:

• Place the current dissolved-gas mix of a transformer in the zones of a Duval triangle.
• Follow how the gas mix moved over a period, as a trail of points.
• Read the gas amounts in ppm and their shares next to the zone.
• Use the triangle that fits your equipment: Triangle 1, 2, 4, or 5, or one of two pentagons.

Choose XY Plot+ when you want to plot one measurement against another without fault zones.

Before you begin

• Prepare numeric PI Points or AF attributes for the dissolved gases that your triangle needs: three gases for a triangle, five for a pentagon. See the table in Choose the triangle type.
• Use the same unit for all gases, normally ppm. The symbol computes shares from the values as they are and labels the amounts "ppm".
• Use the symbol only within your organization's approved diagnostic procedure. The zones describe where a gas mix falls. They do not replace engineering assessment or the applicable standard.

Add and set up the symbol

1. Select Duval Triangle+ in the PI Vision symbol gallery.
2. Drag the three gas data sources onto the display.
3. Right-click the symbol and select Configure Duval Triangle.
4. Open Mapping and keep Duval Type on Triangle 1 (Classic) (1).
5. Select the data source for each gas: methane for Axis A (2), ethylene for Axis B (3), and acetylene for Axis C (4).
6. Close the pane. The symbol shows one point in a zone and the gas amounts below the zone list.

The axis lists start with the data sources in the order you dropped them, so the first data source is not always methane. Check each axis list. The labels on the symbol follow the axis, not the name of your data source.

Common tasks

Choose the triangle type

Use this when your equipment or the diagnostic question needs a different triangle than the classic one.

1. Right-click the symbol and select Configure Duval Triangle.
2. In Mapping, open the Duval Type list (1) and select a type.
3. For each axis (2, 3, 4), select the data source that holds the gas named in the label. The labels change with the type.

The zones and axis captions change with the type. The same gas mix lands in different zones on different triangles.

Type	Example	Axis A, B, C	Zones
Triangle 1 (Classic)		CH4, C2H4, C2H2	PD, T1, T2, T3, D1, D2, DT
Triangle 2 (LTC)		CH4, C2H4, C2H2	N, D1, X1, X3, T2, T3
Triangle 4 (Low Temp)		H2, CH4, C2H6	PD, O, C, S
Triangle 5 (High Temp)		CH4, C2H4, C2H6	PD, O, T2, T3, C, S, T3-H

The two pentagon types, Pentagon 1 and Pentagon 2, plot five gases: H2, C2H2, C2H4, CH4, and C2H6 on Axis A to Axis E. They use the zones PD, D1, D2, T1, T2, T3, and S (Pentagon 1) or PD, D1, D2, T3-H, C, O, and S (Pentagon 2).

Show the history as a trail of points

Use this when you need to see where the gas mix came from, not only where it is now.

1. Right-click the symbol and select Configure Duval Triangle.
2. In History, set Show to ON (1).
3. Set Mode (2) to Interpolated to take one reading per interval, or Summary to aggregate each interval.
4. Under Interval (3), set how often a trail point is drawn, for example 1 Hour.
5. Under Start- and Endtimes (4), keep Display time range, or select a custom range for this symbol.

The trail appears behind the current point. The oldest point is the smallest and the points grow toward the present. The current point is the value at the end of the time range.

Color the zones and label them

Use this when the zone colors must match your organization's standard, or the zone names clutter the triangle.

1. Right-click the symbol and select Configure Duval Triangle.
2. Open Trend Options and then Zones.
3. Set Labels (1) to ON to print the zone names on the triangle, or OFF to hide them.
4. Set Border Color (2) and Border Width (3) for the lines between zones.
5. Under Colors, select a color for a zone, for example D2 (4).

The zone and its entry in the zone list take the new color.

Make the current point easy to find

Use this on a busy display, or when the default red point is hard to see against your zone colors.

1. Right-click the symbol and select Configure Duval Triangle.
2. Open Trend Options and then Point.
3. Set Pulse Effect (1) to ON to draw a ripple around the point.
4. Select the fill in Color (2) and the outline in Border Color (3).
5. Enter a diameter in Size (4).

The point takes the new look. The trail points use the same color.

Move or hide the zone list and the gas amounts

Use this when the symbol is small, or when the zone list or the gas amounts are not needed.

1. Right-click the symbol and select Configure Duval Triangle.
2. Open Trend Options and then Legend.
3. Set Position (1) to Left or Right.
4. Set States (2) to ON to list the zones, or OFF to hide the list.
5. Set Gas Composition (3) to ON to show each gas amount and share, or OFF to hide them.

With States off, the gas amounts move to the top of the column. With Enabled off, both are hidden and the triangle uses the full symbol.

Use the symbol

• Hover the current point to see its zone, the amounts in ppm, and the shares.
• Hover a trail point to see its time, amounts, and shares.
• Hover a zone to see its name and meaning.
• No point: a gas has no numeric value, a mapped data source is missing, or all gases are 0. The zones and axes stay visible.
• Zone Unknown: the tooltip shows State: Unknown and no zone list entry is framed when the point sits outside every colored zone.
• The symbol only displays data. It does not write to the PI System or change other symbols.

Read the zones

A Duval triangle turns three gas readings into shares that add up to 100%. The point is placed by those shares, not by the absolute amounts, so a point in a zone tells you the type of gas pattern, not how much gas is present. Read the amounts next to the zone.

The symbol reports the zone only. What to do about a zone is a decision for your diagnostic procedure and the applicable standard.

Configure the symbol

Right-click the symbol and select Configure Duval Triangle. The first six groups are under Trend Options.

Title

Style

Zones

Axes

Point

Legend

Mapping

History

Trace Options and Numbers

Troubleshooting and limitations

Limitation: One symbol plots one transformer. To compare several transformers, place one symbol for each next to the others.

Limitation: The gas amounts are always labeled "ppm". The symbol does not convert units.

Limitation: The symbol shows the zone of the latest values and a trail of earlier readings. It does not store results or raise alerts.