Electric motors form a significant component in the commercial, industrial, and residential spheres of everyday life. When sudden faults arise, downtime and costly repairs can cause disruptions that will impact the functionality of an entire system. Caring for your motors through predictive maintenance means using reliable strategies to predict when a problem might arise.
This predictive approach can only be successful through the regular monitoring and testing of equipment to identify whether it’s functioning properly, or may be showing signs of wear. Sometimes, professionals recommend data collection as part of a plan for predictive motor maintenance, as past information can help you to set a base level for the equipment and estimate future problems.
Recognizing a Need for Motor Servicing
The first step in identifying the signs of impending motor failure is conducting a visual inspection to record and observe any anomalies to its physical condition. For instance, a motor operating in a rough environment may be corroded and dirty — which may lead to internal problems. If a motor looks damaged on sight, check for a burning odor that might be emitting from the windings or bearings that could suggest overheating from friction or contamination
For motors that appear to be in good condition on the outside, finding internal issues before a breakdown can be more challenging. Having a checklist for predictive maintenance can make it easier to know what to examine, correct, and replace if necessary. Unlike preventative maintenance, predictive maintenance requires periodic readings resulting in maintenance service as needed, with readings becoming more frequent as problems make themselves known, and the machinery itself begins to age.
How to Predict if a Motor Needs Maintenance
To examine the health of a particular piece of equipment, a strategy for predictive maintenance should include numerous inspections, including:
- Oil Analysis and Bearing inspection
- Motor winding and motor current analysis
- Infrared thermography analysis and vibration analysis
Lubrication and Bearing Inspection
Lubrication is essential to the function of an electric motor. Examining the health and status of lubricants can help to determine a problem that may be occurring within the motor itself. For instance, contaminated lubrication will shorten bearing life as will over-lubrication and this is a sign that the machine will malfunction in the near future. If your motor is emitting noise or excessive vibration, this could be a sign that the lubrication around the bearings is not functioning as it should. Alternatively, the symptom might suggest there’s a problem with the bearings themselves.
When checking bearings, remember that some types will need different maintenance tasks according to their motor application and operating environment. If the housing for the bearing is hot to touch, this could indicate that malfunction will occur because of worn or loose bearings.
Motor Winding and Current Signature Analysis
Testing the motor windings should be the next item on the checklist. Periodic phase to ground insulation readings and phase-to-phase resistance readings (which should be within 2% balance) are the most frequent and easiest tests to perform. A very low reading ohm meter is necessary as resistance values may be in the 1/100 ohm range for larger motors and less than 1 ohm for smaller motors. If readings are not balanced or you are not sure about the readings, please consult with Sloan. Depending on the readings, preventative action may be indicated of disassembling the motor and inspecting all internal components to determine whether the motor has seen any winding abnormalities and failures. For instance, burn marks and damaged insulation or cracks could indicate overheating on the windings that will progress to more severe damage. In these circumstances, the motor may need to be rewound. Catching it now may prevent catastrophic damage to the laminations, making the motor potentially non-repairable as motor efficiency will be permanently affected.
Infrared Thermography and Sonic Analysis
Infrared analysis can help technicians to detect faults with connections in an electrical motor, or system overloading issues. These tools can also help to detect abnormalities in the mechanics, such as elevated temperature around couplings or bearings. For instance, if a test shows high temperatures around gaskets or pump seals, this could be a good indication that the motor is heading towards failure.
At the same time, innovative tools can sense sounds and vibrations that a technician may not notice themselves. For example, ultrasonic or sonic systems can sense vibrations between 20 and 100 kilohertz – converting them into signals such as beeps or flashing lights that a professional can use to establish an oncoming problem. This can be particularly useful in predictive maintenance, as under-lubricated and worn bearings, as well as damaged valves and electricals can produce very low frequencies — impossible to detect with the human ear.
Using Predictive Maintenance
Predictive maintenance is a good way to recognize and fix a problem before it occurs within electrical motors. Often, the tools mentioned above work alongside methods for preventative methods to provide a more comprehensive approach to motor care.
How have you implemented predictive maintenance to look after your systems? Have you found that a particular strategy works best for you? Let us know in the comments below!