Metso DNA system troubleshooting

Regular automatic spectrum baseline comparison for critical equipment operation: Select the "Spectrum RMS" trend in the "Trend" window (PDF page 55), set the full spectrum to be automatically saved once a week, and trigger an alert when the deviation between the new spectrum and the baseline exceeds 30%.

4.5 Improper configuration of Intelligent Alarm Handling (IAH) leading to false alarms

Phenomenon: When the device operates at different speeds, the fixed alarm limit often triggers warnings (such as higher normal vibration values at low speeds and lower values at high speeds), or the alarm does not work at all after the speed changes.

Background: Metso DNA's Intelligent Alarm Handling uses a "Notice Curve" instead of a fixed alarm limit. This curve divides the speed range into multiple intervals, with independent alarm thresholds set for each interval to adapt to variable speed machinery.

Troubleshooting steps:

Check if IAH is enabled: In the DNA Operate measurement window, check if there is an "I" symbol on the right side of the feature value bar (PDF page 65). If not, intelligent alarms need to be enabled for this feature value (such as acceleration RMS, envelope peak).

Validate Parameter Group and Recipe: Enter the "Intelligent Alarm Handling" button (PDF page 60). Firstly, confirm the existence of at least one parameter group, such as different groups for low-speed rollers (0-200 RPM) and high-speed motors (2000-6000 RPM). Each group needs to specify the feature value type (such as PEAK-HF, RMS-LF), speed reference trend (rotation frequency or machine speed), notification area (minimum maximum value of speed), and class number (PDF pages 62-63). A common mistake is setting too few classes (such as 5), which results in a rough alarm curve that cannot track the actual vibration trend.

Run notification curves: In the "Running notification curves" window (PDF page 64), select the target device (Process Area ->Machinery ->Eigenvalues), choose the parameter group, and set the time range for calculation (usually at least 2 weeks of historical data when the device is in good condition). After clicking "Run", the system automatically calculates the average value or a certain percentile (default 95%) of the characteristic values in each speed category as the alarm baseline. If no curve is generated after running, check if there are enough valid data points in the historical trend (at least 10 points are required for each class).

View and edit notification curves: Click the button under the "I" symbol next to the feature value to open the curve view (PDF page 66). The curve is in a stepped shape, with each step corresponding to an alarm threshold for a speed class. If the threshold of certain classes is abnormally high or low, you can directly drag the handle to adjust it. Note that the edited curve must be saved in order to take effect.

Delete notification curves to restore fixed alarms: If IAH causes confusion, the notification curves for that feature value can be deleted ("Delete notification curves" on page 64 of the PDF), and the system will revert back to using traditional grouped alarm limits (set in the Scaling Tool).

Best practices:

Run the notification curve only when the equipment is in good condition (check the vibration trend first and remove the fault data points before maintenance).

The amplitude range in the parameter group is set wide enough (e.g. 0-20 mm/s) to avoid compressing the ratio due to individual high points.

The recommended number of classes is 10-15, which can smoothly track speed changes without overfitting.

Regularly (quarterly) rerun the notification curve, as the equipment foundation vibration level may drift slowly due to wear or maintenance.

Preventive maintenance and system optimization suggestions

In addition to troubleshooting when faults occur, proactive maintenance measures can significantly extend the trouble free operation time of the Metso DNA system:

Regular calibration of sensors: The sensitivity drift of RVT/TT-125 is usually less than 1% per year, but in high vibration or corrosive environments (such as G3 industrial atmosphere), it is recommended to use a portable vibration calibrator for on-site calibration every 12 months. For the temperature channel, use a dry well furnace to verify at two points, 50 ° C and 100 ° C.

Cleaning and fastening of I/O modules: Open the cabinet every six months and use low-pressure compressed air to remove dust from the ACN I/O M120 module, with a focus on checking for signs of oxidation on the front-end connectors. For modules with optional conformal coatings (suitable for G3 environments), avoid using solvents for wiping.

Controller redundancy test: Perform a manual redundancy switch once every quarter (right-click on the controller node in DNA Operate ->"Switchover"), and observe whether the backup controller completes takeover within 10 seconds without losing process data. Simultaneously check if the SD card configurations of both controllers are synchronized (using the 'Synchronize SD card' function).