The new generation of HMIs has a huge impact on operator performance:

• they improve the operator’s ability to detect abnormal situations before an alarm occurs by a factor of five;

• the operator success rate in handling abnormal situations is almost 100 percent; and,

• the time it takes to correctly handle the situation is almost half that of operators working with traditional HMIs.

Besides grayscale graphics and the consistent and careful use of color, shapes and motion,

high performance graphics typically include the following features to maximize the attention and effectiveness of the operator:

• Alarm priority colors are used for alarms only

• Consistency in graphic layout to ensure operator situational awareness

• Tab-based navigation for one-click access to primary displays

• Embedded trends, which display historical data in a graphic to efficiently draw

the attention of the operator to abnormalities and deviations

• The normal operating range and high / low alarm limits are shown for

each item of equipment using an intuitive bar graph (see Figure 5)

• Bubble-up alarming allows the alarm with the highest priority to ‘bubble up’ 

above lower priority alarms associated with the same device