Question About online preventive maintenance of Induction motors 3

[frztrb]

Hi All

I would like to know , whether we need to have maintenance in a preventive way , if the induction motor that usually works in a constant speed , 400 V , 40 A ? when it has an inverter that also (I am not fully informed in this area so if you let me know what are the objectives of the inverter) , so in this case the electric motor has a complete control panel , does it still need a preventive maintenance , one idea is that since the number of failuares are not so high , for example it's more probable that the motor gets an electric failure and following problems for bearing and vibrations and stop , for example if the inverter fails, which , without instruments , it is hard to understand if the problem is from the inverter or the motor

yet it is less probable that the problem arises from the mechanical part, I mean the bearing breaks itself

so is a maintenance necessary ?

Thank you

 

[jraef]

It's difficult to discern what you are getting at, but it sounds as if you have a motor driven by an inverter, and you are having repeated failures of the motor, sometimes from winding failures, sometimes from bearing failures. I understand that you are asking if this is maintenance issue, but quite frankly, these symptoms are know issues with inverter run motors. In almost all cases, they stem from lack of attention to details on the methods and materials used to install the motor and drive. This is common problem when the drive is sold to someone unfamiliar with the issues and either not given the proper training or manuals, or feels they cannot afford the extra steps necessary for a successful installation. The fact that you did not recognize these as common problems indicates that you fit this category. Its ok, we all started somewhere and it was painfully for all of us, you just need help and knowledge.

My suggestion would be to start with an expert in the specific inverter drive you have now, if someone is avaiable to you, who can instruct you on ways to mitigate and avoid these problems. If there is no one available in your area, look for a local Electrical Engineer with specific experience in Inverter Drive installations. You have issues that have solutions, the details of which are complex and are best served by someone who can observe them on site.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[LionelHutz]

My suggestion would be to get rid of the inverter since it has no place in a constant speed application. The inverter is just a expensive waste of energy which has the added bonus of making the system less reliable.

 

[electricpete]

I agree entirely with previous two posters.

Some more food for thought:

The bearings may need to be greased periodically (depending on size/speed/enclosure).

Don't know if it's an ODP motor with filters… those would require maintenance.

Periodic visual inspection may be a good idea. Especially if there are people available to easily monitor it and environmental factors (outdoor) that may hasten a variety of degradation mechanisms - corrosion, dirt, rodents etc.

Monitoring of vibration pays dividends in some applications. Depends in part on how easy it is to monitor and what is the cost of failure.

Large critical ODP motor outdoor probably needs to be disassembled for cleaning/inspection every 10 or 20 years. Other monitoring strategies may play a role here also.

There might be more to say. But would be better for you to give us an idea of machine size, speed, bearing configuration (open, shielded, sealed), environment (humidity, other factors), is there a a skilled operating / maintenance / predictive staff available and how far, are the people around that would hear the machine if noise starts changing (you might take some credit for that), what is the consequences of failure etc. And of course tell us more about this inverter, it's purpose and environment.

All of these will play a role in any recommendation / decision and ultimately will still be somewhat subjective.


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(2B)+(2B)' ?

 

[jraef]

... if the induction motor that usually works in a constant speed

So yeah, I guess it depends on your definition of "usually". If that means it NEVER varies in speed, then I agree, the VFD is contraindicated. If it MUST be capable of changing speed, then you have to address the issues that make it possible and motor friendly.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington