Are you looking for ways to minimize downtime in your HVAC system? Would you like enhanced awareness of potential maintenance problems before they reach a critical stage? condition-based monitoring (CBM) may be the solution you need.
CBM is a type of predictive maintenance strategy that uses sensors to continuously measure the status of equipment over time. CBM is not a new technology for predictive maintenance; however, it is new to implementation within variable frequency drives (VFD). When included as a software feature add-on in VFDs, CBM increases customers’ knowledge of what is happening in their systems so they can be notified of maintenance concerns prior to issues becoming critical, thereby reducing system downtime.
Peace of Mind with 24/7 Monitoring
CBM can monitor three points: motor stator winding, load envelope, and vibration. With motor stator winding monitoring, the VFD uses its current monitoring capabilities to detect short-circuits in the motor before the motor burns out. Load envelope monitoring compares actual system performance with baseline data to determine if components are running optimally or if there are performance issues. Vibration monitoring can detect mechanical misalignment, wear-out, and looseness across all VFD speeds.
When the VFD is initially commissioned, the embedded CBM software can be programmed to run a baseline of normal operation over a specified time range, from a few days up to six months. Once the baseline is established, thresholds are set, and the VFD will constantly be comparing what is happening in the system with the standard baseline. If the current operation goes beyond the threshold, the VFD will trigger a warning to notify the user that something is wrong.
There are two levels of warnings that can be programmed accordingly. If the system goes considerably beyond the two warning thresholds, the VFD can trigger an alarm and discontinue power to the motor until the fault has been cleared by a technician. These notifications can be shown on the VFD display and pushed to the building automation system and/or remote monitoring cloud services.
Insight for Maintenance Teams
CBM is not meant to eliminate maintenance teams but, rather, increase their real-time knowledge of what is happening in the system. If the user is stocking motors or running into long lead time issues when their motor fails, CBM can help bridge the gap. Short-circuits in the motor winding occur over time, so by detecting them early, the end user can be prepared to replace the motor prior to the problem reaching a critical stage.
Motor stator winding monitoring will send a warning prior to motor failure and allow for the additional time that is needed to obtain a replacement. Load envelope monitoring can send warnings to maintenance staff about leaks in the water system, clogged air filters, broken pump impellers, or pumps that have become fouled/sanded. These warnings provide useful information to help keep the system running efficiently and smoothly. Vibration monitoring will keep track of any changes in vibrations that would start to wear out mechanical equipment more quickly. The VFD will monitor acceleration/deceleration and all speeds in-between that the VFD is running. Operators can choose to monitor any or all of these points in their systems.
In the current climate of increased lead times and expectations of decreased downtime for systems and buildings, CBM will give you an edge. Most maintenance teams will monitor only some of the points CBM is capable of monitoring. Those teams may also only go out with a meter at a specific point in time when the VFD may be operating at a speed where the issue is not occurring. Undetected problems lead to the continued degradation of components in the system, which may not be noticed until the system fails and operation is halted. CBM will keep you notified at all frequency levels 24/7/365.
For further information and questions on Condition-Based Monitoring, and/or help in determining the right VFD for your application, reach out to Danfoss Drives at (888)-DANFOSS or a local highly qualified Danfoss Drives partner.
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