How do you prevent and diagnose faults and failures in electrical machines?

Good suggestion, I want to add a line. Insulation failure can also happen due single phasing, so proper care of such protection is also necessary in addition to the above.

When load on phases are not balance This can make a particular phase winding weak .The distribution of loads must equal having a plus or minus difference can be accepted ,but when loads have great different it affects the performance of a machine.

Preventative maintenance is the cornerstone of any well maintained asset. Scheduled maintenance ensures asset is always lubricated, inspected, and obvious wear and tear are repaired. Using diagnostics technology also helps by analysing hard to see wear and tear, so major components can be exchanged before your asset suffers a catastrophic failure. Using both in tandem with each other can greatly increase the longevity of your asset.

One effective strategy is to regularly monitor and maintain the insulation system. This involves routine inspections to detect any signs of wear, damage, or contamination on the insulation material. Proper ventilation and temperature control can also prevent overheating, which can accelerate insulation degradation. Employing surge protection devices and voltage stabilizers can help protect the motor from voltage spikes and transient surges. Furthermore, adhering to recommended operating voltage and current levels, along with implementing a regular maintenance schedule, including testing the insulation resistance, can significantly reduce the risk of insulation breakdown and extend the motor's operational life.

I would like to add that fewer breakdowns in the process can be achieved with strict adherence to Parameters evaluation as per the checklist as part of the PPM Schedules

Let's add information on variable frequency drive (VFD) induced bearing failure. This occurs during the high voltage switching of a VFD. During normal operation, a capacitive voltage is created between the stator and the rotor shaft. This voltage builds until the dielectric capacity of the bearing grease is overcome and the voltage discharges to the bearing housing, causing an electrical arc. The process continues and overtime damages the bearing, eroding a groove in the bearing wall, this is called "fluting". Eventually the bearing must be replaced. Implementation of proper shaft grounding techniques can help to reduce or eliminate this problem.

Enthusiase to use double sealed shielded bearing which can be used for both lower and higher loads. Lubrication and regular cleaning at regular intervals are also required to avoid bearing failure.

Also for higher frame motors shaft movement is necessary in every week when stored in ideal condition. Else bearing will damage.

1)Manufacturers recommended lubrications and frequency of application must be adhered to. This means that for every 1000hrs use then one squirt/pump/dose must be applied (caveat, with vsd’s ramping and running at say 50% then doseage is fettled accordingly or you risk overdosing running into windings or oppositely drying out). 2)Alignments on all axes must be checked and torqued bi-annually if not quarterly. 3)Terminations upstream and downstream to motor must be checked (including checking for pitting of isolator/contactor/relay terminals) 4)control circuits and associated control systems must be checked and calibrated and/cleaned/torqued. 5)regular monitoring equipment and software should cater for noting recurring problems in the future

In my years as a maintenance engineer, I encountered a recurring issue: bearing damage in our electrical machines. It caused costly downtime and repairs. What I learned was a valuable lesson in proactive maintenance. By diligently adhering to manufacturer recommendations on lubrication, alignment, and maintenance, we significantly reduced the instances of bearing damage.

Hello, I am Sohail, a power engineer in Iran, and for about 25 years, I have worked mostly in the field of electric machines, especially stone crusher motors, in mines. These machines are mostly asynchronous, and the biggest challenge was when, despite meeting all maintenance standards, we saw After changing the type of brushes, the friction rises on the slip rinks, and the moment the engine is separated from the liquid starter, it is at 70% of the rated speed.

I encountered a challenging issue with rotor imbalance that left a lasting impression. We had a critical machine exhibiting excessive vibration and noise, resulting in frequent breakdowns. Digging deeper, I discovered that the root cause was rotor imbalance. What I learned from this experience was the importance of meticulous pre-installation procedures. We started by rigorously balancing the rotor during manufacturing, ensuring that its center of mass aligned perfectly with the axis of rotation. Moreover, we emphasized the criticality of maintaining clean and debris-free rotor surfaces.

In addition to abnormal temperature, unusual sound and vibration arises from Rotor imbalance, bearing damage or loose connections etc. A thermographic survey should also be part of an ongoing routine maintenance programme ensuring that your machines and electrical system remains in tip-top health. This prevents the risk of it overheating due to a lack of care and attention. The result from the thermographic survey will help diagnose potential fault in machines and electrical systems such as missing insulations, moisture ingress, condensation and mold growth. So also, performing root cause analysis can help identify where a problem began and what caused it. Performing a root cause analysis is similar to retracing your steps.

Collect the evidence related to the problem, such as symptoms, affected devices, or circuit breakers. Analyse the evidence and eliminate any irrelevant or contradictory information. Locate the fault by tracing the wiring or using a multimeter or other testing device. Determine and remove the cause of the fault, such as a loose connection, a short circuit, or a damaged component. Rectify the fault by repairing or replacing the faulty part or wiring. Check the system by testing the voltage, current, and resistance, and ensuring the devices work properly.

It is important to ensure proper connection of cables during commissioning to reduce the risk of sparks and also damage to the wires; Surge protection and working within the specified range and working temperature of the equipment is also important

Appropriate protective devices can go a long way in preserving the lives of electrical machines. Consider a phase failure relay to prevent 3-phase motors from “single-phasing” and an adequately rated overload relay to protect against high motor running current. Mission-critical machines need to be monitored while addressing maintenance issues from a proactive standpoint. Priority should be given to machine running parameters such as current drawn, current imbalance, system frequency and line voltages, so that the health of the system can be ascertained both on the supply side and load side, leading to improved decision-making. Thus underscoring the importance of autonomous maintenance practices.

Regular review of maintenance procedures ensuring each steps are still valid, proper tools and TMDE's are listed and applies to the equipment being maintained. More importantly, personnel performing the maintenance are qualified and possess the required skill and knowledge. Management should ensure that junior personnel are being trained in performing these maintenance.

Here's some other things to consider: - any dust and grime build up - foreign objects or animals that may get itself stuck like lizards or cockroaches - contractors, incoming electrical systems