WEG motor reliability
WEG motor reliability
(OP)
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.





RE: WEG motor reliability
RE: WEG motor reliability
I've run into that with Weg before. In Brazil where Weg is made, they use a lot of 690V in the minimg industry, so instead of making 400/230V motors, they make 690/400V motors and 400V users are expected to read the installation manuals and connect them in Delta. Happens here in the US as well, we are used to dula voltage motors being 460/230V with the connections for 460V being shown as "High" voltage. But some Weg motors that arrive are actually 720/460V motors (it's actually the same motor as 690/400V, just for 60Hz applications). Everywhere else in the world beside Brazil, installers are used to connecting 400V (or 460V) to the "High" voltage pattern and never read the manuals for the motors, because they have connected hundreds or thousands of motors.
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RE: WEG motor reliability
John
RE: WEG motor reliability
It is not just in Brazil that they supply 400/690 volt motors, but much of the 50Hz world they supply motors above 4KW that are designed for star/delta starting. This is historical as in many areas, above 5KW or simiar, you had to use a star/delta starter (wye/delta starter).
Here in New Zealand, it is the norm for motors to be delta connected for 400V for motors 4KW and above and the exception for them to be star connected for 400V.
I agree with your proposal of the motor being incorrectly configured for the voltage. Makes perfect sense.
Best regards,
Mark
Mark Empson
Advanced Motor Control Ltd
RE: WEG motor reliability
Regarding WEG motors. I find them good quality motors generally. I wouldn't have thought the motors were the cause.
RE: WEG motor reliability
Keith Cress
kcress - http://www.flaminsystems.com
RE: WEG motor reliability
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: WEG motor reliability
Basically, the problem is the motors are machine wound with the windings just mashed into the stator. There is nothing else but some insulation in the slots and insulation over the lead connections. In some cases, this leads to the start and end of a winding being against each other or even the winding near the ends of the coils on different phases being against each other. Despite the claims that the wire insulation can handle the high voltage levels this creates between these touching winding, it doesn't and it fails.
This isn't isolated to WEG motors. I've seen the same thing from a number of manufacturers. It seems to be a numbers game. The manufacturers push the limits of the materials to build the motor as cheap as possible since the extra warranty claims cost less then the amount saved in manufacturing.
The only real fixes are to buy more expensive motors where the manufacturer will show you how they keep this from happening or get the motor rewound at a good shop where they take care to avoid placing too much voltage across the wire insulation. You can also just hope the coil placement has shifted in the next batch of motors and you eventually get ones that don't fail.
RE: WEG motor reliability
It brings to mind another thought: Does WEG consider these motors "inverter duty" ?
Part 31 of NEMA Standard MG1 gives requirements for such motors, including withstanding "voltage spikes" with peak voltage of Vp = 3.1*VLLrms and with rise time as short as 0.1 microsecond.
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(2B)+(2B)' ?
RE: WEG motor reliability
Some of this was in table form so it is less than clear here, but the salient points are there and I've highlighted a few.
A 1600V peak voltage and a .1 μs rise time is not what most "Inverter Duty" motors are designed for, it's more like 2000V and .025 μs now. This is better than the old 1200V ratings, but not the best in class by any stretch. Most likely these motors should have had reactors on them at the very least, if not some decent motor lead filters.
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: WEG motor reliability
RE: WEG motor reliability
RE: WEG motor reliability
Here, if you want an "inverter duty" motor the supplier drills 2 holes in the case and pins a "inverter duty" tag on the motor.
RE: WEG motor reliability
RE: WEG motor reliability
If that is the case, I fail to see how using one brand of drive over another would make much of a difference. It's not as though ABB are newcomers to this issue, in fact I would venture to say that WEG are the neophytes by comparison of the two companies.
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: WEG motor reliability
Instead they recommended to tear out the old drives and put in WEG drives.
Sounds perfectly logical to me. But only on 12/04.
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(2B)+(2B)' ?
RE: WEG motor reliability
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(2B)+(2B)' ?
RE: WEG motor reliability
Typically, a re-wind shop will attempt to wind the coils so the start is on one side and the end is on the other side. They also watch the voltage per coil so that even with the start and end of the coil against each other the coil doesn't fail. The contact we talk to every now and then attempts to use 50V/coil based on their past experience. They also use phase-phase paper and are careful where the windings in the end bells all land. Compared to that, we have seen motors inside motors which were factory wound at 200V/coil or higher these days without any phase windings and without much concern about seperating phases.
RE: WEG motor reliability
Yes, very often happens that a manufacturer or rewind shop uses the maximum number of parallel circuits, without taking into account the "volts / coil" ratio (at random wound coils).
Also, there is often a lack of insulation between the phases.
BTW, is there any other requirements or recommendations for materials and working procedure when rewinding standard to an inverter duty motor?
RE: WEG motor reliability
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.
RE: WEG motor reliability
RE: WEG motor reliability
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.
RE: WEG motor reliability
RE: WEG motor reliability
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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