two identical machine VSD faults minutes apart
two identical machine VSD faults minutes apart
(OP)
Good morning,
Upon starting the plant Monday morning we had major issues with our compressors, Both went down on a VSD error over current. Putting in a bad spot at the moment, I reset one of the machine and cleared the error displayed and attempted to restart. It errored again, on my third attempt the machine stayed running and hasn't stopped. However, the same twin machine next to it did not fair very well. After the plant pressure was up to par, I put the second machine on line (stand by) as I always do, to be ready to help when required the air pressure dipped and it was asked to come on line. It ran for about 30 seconds and had the same error as the first. When I cleared the error and attempted to restart I was witness to a large flash from the bottom of the motor. After megging the motor I learned the windings were shorted together and now have the 200hp motor out to the repair shop to be rewound. I consulted the manufacture of these compressors asking what the heck happened, and the only thing they can contribute the problem to is, this past Sunday was by far the most hot and humid day we have had in a few years. Not to forget we were having several storms and rain this same morning. They fear the motors condensated inside and when I attempted to start it found the weak spots in the winding insulation. I'm not comfortable with this at all and it does give me a sound reason why this had happened.
Both these machine are VSD driven 200 hp Sullair compressors with WEG motors. After all the dust settle and we calmed down we went looking for water but found nothing. Has anyone of you folks seen something like this? Manufacture claims it happens down south a lot. We are near a oil change and test the oil monthly for breakdown. Sample from last month prove the oil is fine but haven't seen the results to the sample pulled a week ago. My thought is I have a mechanical issue some where.
Upon starting the plant Monday morning we had major issues with our compressors, Both went down on a VSD error over current. Putting in a bad spot at the moment, I reset one of the machine and cleared the error displayed and attempted to restart. It errored again, on my third attempt the machine stayed running and hasn't stopped. However, the same twin machine next to it did not fair very well. After the plant pressure was up to par, I put the second machine on line (stand by) as I always do, to be ready to help when required the air pressure dipped and it was asked to come on line. It ran for about 30 seconds and had the same error as the first. When I cleared the error and attempted to restart I was witness to a large flash from the bottom of the motor. After megging the motor I learned the windings were shorted together and now have the 200hp motor out to the repair shop to be rewound. I consulted the manufacture of these compressors asking what the heck happened, and the only thing they can contribute the problem to is, this past Sunday was by far the most hot and humid day we have had in a few years. Not to forget we were having several storms and rain this same morning. They fear the motors condensated inside and when I attempted to start it found the weak spots in the winding insulation. I'm not comfortable with this at all and it does give me a sound reason why this had happened.
Both these machine are VSD driven 200 hp Sullair compressors with WEG motors. After all the dust settle and we calmed down we went looking for water but found nothing. Has anyone of you folks seen something like this? Manufacture claims it happens down south a lot. We are near a oil change and test the oil monthly for breakdown. Sample from last month prove the oil is fine but haven't seen the results to the sample pulled a week ago. My thought is I have a mechanical issue some where.





RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
I am betting "they" are right. Have you tested the motor to determine if insulation failure has occured?
RE: two identical machine VSD faults minutes apart
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RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: two identical machine VSD faults minutes apart
And you are near the Great Lakes?
Keith Cress
kcress - http://www.flaminsystems.com
RE: two identical machine VSD faults minutes apart
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: two identical machine VSD faults minutes apart
I don't think you and I (being West Coast guys) have an appreciation for how this works in the Southeast. The Dew Point at 90% humidity can be 90 degrees F!
Cool is relative...
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: two identical machine VSD faults minutes apart
A VFD will find any weak spot in the motor insulation, be it a poor winding job or weakened due to moisture or anything else for that matter.
If you are in a damp humid enviroment then a strip heater that is powered when the motor is stopped is a good idea.
What did the re-wind shop find inside the motor? Did you ask them to take a good look at the failure?
I have seen a number of motors where the factory winding job was poor and that was the weak spot where they failed. Actually, I think every time we've been dragged into a VFD related motor failure problem and we look in the motor we find the same thing. Typically, there is a spot on the end windings where the wire from different phases cross and touch each other imposing all or most of the phase to phase voltage directly on the varnish. Despite the claims that the varnish is good for 3kV or 4kV or whatever they're up to this week, it still fails. Add some moisture or humidity to that spot and it's even more prone to fail.
RE: two identical machine VSD faults minutes apart
Davidbeach had asked if it was cool in the morning to answer that yes it was, we hit 91 on Sunday and very humid, then Monday morning we were in heavy storms and pouring rain about 65 degrees. I'm only 30 mile from the Saginaw Bay.
RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
Apply 120 Volts to a 240 Volt rated heater.
Web page;
http:/
Part number;
129365 OT-817 IRON 240V1P 175W
Or
Web page;
htt
Part numer;
121523 SL-N-1-10-0-10-S-120V-50W
If you have room inside the end bell, lay one of these inside the end bell at each end of the motor.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: two identical machine VSD faults minutes apart
Feel free to stop by,I could tell you where the fish are if that the nature of your visit, any suggestion for this weekend until I receive these heater? Wrap the motors with shipping blankets, turn the wall heaters on and keep the whole room warm? I starting to buy into the condensation theory it seems to be the only thing that the two have in common. you had asked if the motor was tested prior to rewind yes we have a dual wye wound motor and it was between the two wyes was what was shorted. We had also surge test the motor. It was tough to see on the scope but you could hear it plain as day. Sounded like a card in bicycle spokes. Please be patient with me, this was a new experience for me. I have no one else to turn too. Thanks again everyone.
RE: two identical machine VSD faults minutes apart
In the mean time, a controlled steady temperature in the room is the best.
Rising temperature combined with a rising dew point are the conditions to be avoided. The motor core temperature does not rise fast enough and when the dew point goes above the core temperature condensation results.
Normally raising the temperature of a mass of air drops the relative humidity. But should a mass of warm moist air drift in from a nearby body of water or swamp, the stage is set for internal condensation.
Until you get some heaters, a steady temperature and no air changes is the best way to avoid condensation.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: two identical machine VSD faults minutes apart
If not, you can possibly create a control circuit to make use of the DC Injection Braking feature to do the same thing (the MWH feature is actually the same capability with different logic). What you do is create a "2nd motor profile" that you engage when the motor is going to be off for a long time. Use a Smart Relay to call that 2nd profile and to initiate a pulsed "Run" command, with the drive set for a preset speed of 0Hz, for just a second and then turn off again. This triggers the DCIB, which you set for the maximum time it will allow, but set the DCIB current for about 10% of the FLA. Then just recycle the pulsed Run command again after the DCIB times out. If you want, use a temperature sensor to only initiate this system when the temperature is low enough, but that's tricky because its a moving target with varying humidity (and humidity sensors are usually spendy).
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: two identical machine VSD faults minutes apart
Sounds like you are on top of the testing part, good luck with your new motors and let us know what happened.
P.S. Listen to Jraef's advice on the VFD, he is a wizard at this stuff.
RE: two identical machine VSD faults minutes apart
2571
RE: two identical machine VSD faults minutes apart
2571
RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
2571
RE: two identical machine VSD faults minutes apart
wye to wye ? cross-talk ? Thye should be clearer.
RE: two identical machine VSD faults minutes apart
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: two identical machine VSD faults minutes apart
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: two identical machine VSD faults minutes apart
RE: two identical machine VSD faults minutes apart
Another point. When a VFD trips on something as serious as current fault; I would check out the load, the motor, connections, etc before simply resetting the VFD and trying again. Faults in VFD's are there for a reason and had there been a major issue relating to a current fault, then resetting the VFD could create bigger problems with the VFD-i.e. bang!