Maintenance and commissioning of ABB KPM KB2 paper breakage detector

The debugging of KPM KB2 is not simply about setting a fixed threshold, but requires the system to "learn" the actual lighting conditions on site. Divided into preliminary debugging and final debugging.

3.1 Preliminary debugging and signal optimization

Set the system to "Maintenance" mode, at which point the paper break relay is disabled to prevent false shutdown signals during debugging.

Use a dry paper to simulate the "paper on" state and place it in the normal position in front of the sensor.

Go to the Maintenance ->On line signals menu and observe the signal strength. Normally, it should be between 50-500. Adjust the angle of the sensor head to maximize the reflected signal (usually perpendicular to the paper surface).

Environmental light monitoring: Check the Environmental light parameter, which must be below 60%. If the ambient light is too high, the RX Gain can be reduced through the Measurement config menu, or external strong light sources can be physically obstructed.

3.2 Collecting reference values

In maintenance mode:

Simulate paper breakage: When there is no paper on the machine, press the SAMPLE key to store the current signal as "Break level".

Simulate paper: When the paper is running normally, press the SAMPLE key to store the signal as "Paper level".

3.3 Perform Auto limit calculation

This is the most crucial step. The system will calculate the Paper to Break Ratio based on the two sets of data you collected, and list the ranking of RGB and their combined signals in the paper to break state.

Go to Configuration ->Auto limit&Auto arm ->Calculate Auto limit.

The system will prompt which signal (such as G or B channel) has the largest difference ratio. The signal that usually ranks first is the best paper breakage detection signal.

Press the right arrow and ENTER, the system will automatically set the detection limit to the midpoint of 50% of the signal Paper and Break levels, and automatically determine the detection direction (such as Break<Limit).

Turn on the alarm (Auto arm), set the high and low limits and drift alarm direction.

Finally, switch the mode to 'Detect enabled' to enable paper breakage detection.

Attention: The final debugging must be carried out under real paper machine operation and real temperature environment, as thermal expansion and contraction will slightly change the mechanical distance.

Typical troubleshooting and countermeasures

During on-site operation, the faults of KPM KB2 are usually manifested as "false alarms" or "no alarms", and its built-in online signal monitoring and event logs are powerful tools for troubleshooting.

4.1 Alarm: Environmental light is too high

Phenomenon: The system detects external light interference, causing signal distortion and even triggering maintenance alarms.

Troubleshooting:

Is the sensor head too close to the paper (too reflective)? Adjust to 10-30 cm.

Is there a strong light source nearby directly shining on the sensor head? Move the light source or install a light shield.

Is the surface of the paper too shiny (with strong reflection)? Slightly tilt the sensor angle.

Solution action: lower RX Gain in Measurement config (for example, from 1.0 to 0.5) to reduce reception sensitivity.

4.2 Alarm: Drift Alarm

Phenomenon: The signal level gradually decreases, triggering a drift alarm.

Reason: The fiber optic lens or sensor hole is slowly contaminated by dust or paper wool, or water enters the sensor head, causing scaling on the fiber optic end face.

Troubleshooting: Check if the purge air has insufficient pressure or if the air source contains oil or water. If the signal shows a slow downward trend in online signals, it is necessary to arrange for fiber cleaning.

4.3 Alarm: Signal out of range, clean measures. probe (signal out of range, probe needs to be cleaned)

Phenomenon: The signal level is extremely low (below 3) or extremely high (above 1000).

Troubleshooting: There may be shredded paper directly sticking to the sensor head, blocking the view. Or the sensor hole may be completely blocked. The probe needs to be cleaned.

4.4 Communication failure: Optic data timeout

Phenomenon: Communication between the display unit and the connection board is interrupted.

Troubleshooting:

The flat cable on the measuring board is loose. Re plug and tighten.

Motherboard malfunction. If the error persists after restarting, the measuring board needs to be replaced.

Deep Maintenance: Fiber Optic Probe Cleaning Guide

When the air blowing system cannot remove stubborn dirt, it needs to be disassembled and cleaned. Improper operation can easily damage quartz optical fibers.

Disconnect the fiber optic connection of the display unit, unscrew the conduit sleeve, and allow the fiber optic cable to slide inside the conduit.

Remove the fastening screws at both ends of the sensor head, and remove the end plate and locking ring.

Carefully extract the fiber optic cable and gently wipe the lens end face with a cotton swab dipped in anhydrous alcohol. It is strictly prohibited to use hard objects to scrape.

When reinstalling, make sure that the two "eyes" of the fiber are centered and aligned with the holes on the stainless steel tube. If it is eccentric, the light path will be blocked, resulting in extremely weak signals.