WEG motor reliability 5

[yorgi]

We have just fitted four lowara pumps that came with WEG motors (37kW 400V 2 pole) . These motors are controlled by ABB acs 800 active front end drives. Within a week we had lost Three of the four Motors, motors taking very large currents and tripping on overcurrent before they got anywhere near rated speed . pumps free motors even ran uncoupled and still failing. Has anyone else experienced these issues and level of failure with WEG motors , We have now fitted ABB motors to the same drives and pumps and have run for the last 3 weeks non stop.

 

[gattie]

There could be a quality issue regarding the winding wire insulation - I've had cases where inferior low cost materials were used in manufacturing particularly, where copper varnish coated winding wire was involved.
The Random or 'Mush' method of winding & installation of motor stator coils is an ancient
proven method for low voltage motors.
Any starting & speed control devices (eg:vacuum contactor or VSD) that generate abnormal voltage spikes will find a weak spot in conductor insulation.

 

[ScottyUK]

Is there some direct relationship between temperature class (F v's H) and suitability for VFD operation, for example is Class F better than B, but worse than H? Or are the synthetic materials used in Class H insulation systems also better able to withstand impulse voltages? The latter sounds more plausible to me.

 

[ozmosis]

It is worth noting that the VFD used is an AFE (active front end) and they operate on a higher DC link voltage than a 'standard' 6 pulse rectifier pwm drive. This means the output peak-peak voltage will be somewhat higher than normal, I'm not sure of the exact figure but around 10-15% higher.
Normally, this would not pose too much an issue on a cable length of 30m and the fact yorgi has advised that there is also a dv/dt filter fitted but if there was some problem with the WEG motor to start, there is a possibility the higher p-p volts could find out this weakness quickly.
Yorgi, your opening question related to how others see WEG motors regarding reliability. I think the responses from most highlight a similar theme that 'generally' the product is ok but as this post has developed then it is clear that the issue is quite different and it seems that the local service and support is very questionable. This is a different issue but probably more important; you can have the best product in the world but if the local support is poor it will mean this will always be the common denominator.

 

[yorgi]

As a final update on this problem we have now changed out the remaining 2 failed motors. The same fault has been found on inspection of the failed WEG motors. We retrofitted ABB motors and have had no further failures to date. So as a summary we have had a 75% failure rate on the 4 WEG pump motors supplied as original eqyuipment by LOWARA. The remaining WEG motor is still in operation but we have an equivelant ABB as a spare incase of failure. When I contacted LOWARA they told me that they fit WEG because they are the cheapest motors ( chinese brands excluded) on the market and if they quoted with a major manufacturers motor fitted they would be less competitive. They further added that they would fit ABB, Siemens, Leroy Sommer etc if requested at an additional charge and further added that this was quite common for supply into the major utility companies who wont touch WEG. On purchasing the ABB motors we noticed that there is a price differential of about 25%. Maybe we were unlucky but to exhibit this level of failure has determined that we will fit Siemens Leroy Sommer or ABB on all our future schemes and also as replacements and retrofits. In fairness to WEG they immediatly and repeatedly offered free of charge replacements. However for us it is not so much the cost of the replacement its the down time. Many thanks to all posters for your observations and welcomed advice.

 

[jraef]

Thank you for the feedback.

I had very similar experiences (2 decades ago) with Weg motors on rock crushers. Over 50% infancy failures, great customer service in that they supplied immediate replacements via air freight at their cost, but the cost to me was well beyond the cost of the replacement motors. I lost an OEM customer over it because of the delays involved.


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