Danfoss VLT 2010 comes up with alarm - Page 1
Forum section: electronics / beginners

author: Halvmand
author_rank: Regular Contributor
timestamp: May 12, 2016, 08:48:51 am
content: I've bought a variable frequency drive, but when i connect the power it just comes up with an alarm. The alarm says: ALARM Trip over current.I have the manual, but nowhere it says what the fault may be other than a shorted output. And I don't even have anything connected to the output.It don't smell funny and it is supposed to be new, but stored for a little while.Is there anyone out there that have experience with these things?Thanks in advance.

author: EPTech
author_rank: Regular Contributor
timestamp: May 12, 2016, 09:25:19 am
content: Hi There,A very basic test you can do is to measure whether there is a short between the DC bus and the outputs. If the drive has got external connections marked DC+ and DC-, you can even do it without opening it up. There should NOT be any short or low impedance path betweenDC- and L1, L2(or N for single phase), L3, R, S, TDC+ and L1, L2(or N for single phase), L3, R, S, TIf it does, you may have a busted rectifier or IGBT. In case of the smaller inverters, they are often integrated in a single power module.Good hunting.

author: Halvmand
author_rank: Regular Contributor
timestamp: May 12, 2016, 03:19:03 pm
content: It has a dc bus. When the unit is on the voltage is about what you would expect rectified 240 mains voltage would be.Spare parts like the triac modules I guess are proprietary devices and are hard to come by? What's your experience repairing frequency drives and the like?

author: EPTech
author_rank: Regular Contributor
timestamp: May 12, 2016, 05:22:04 pm
content: Hi There,I repair power supplies, inverters and all kinds of industrial electronics on a regular basis.What is het current limit parameter (209) set to? Also check whether there are some weird motor parameters set.Try a factory reset and start from there. If the problem persists, try the measurements I suggested.Goog hunting.

author: Halvmand
author_rank: Regular Contributor
timestamp: May 12, 2016, 05:30:34 pm
content: Thanks for the advice. I'll report back when I get to fixing it.

author: Halvmand
author_rank: Regular Contributor
timestamp: May 13, 2016, 07:23:36 pm
content: There is no short between the dc bus and the outputs. Between any two outputs i measure about 10 Mohm.I don't know if I am able to do a factory reset, since after the unit powers up the alarm immediately comes up and I'm not able to do anything.

author: Halvmand
author_rank: Regular Contributor
timestamp: May 13, 2016, 08:11:35 pm
content: The igbt module is a toshiba mp6750 if anyone should know some thing about them.Edit: the model is a Danfoss model 20101 phase in3 phase outThe unit just blinks the alarm led and says it's tripped because of over current. And that is with or without a motor attached. I tried without anything connected to the output at first.I'm 100% sure I hooked it up correct the first time, since it just came with that alarm.Could the igbt module have failed without having obvious shorts?

author: EPTech
author_rank: Regular Contributor
timestamp: May 16, 2016, 10:32:50 am
content: Hi there,The over current trip usually requires a power on reset but you should still be able to access the parameter menu to adjust the trip level or perform a factory reset. See the manual on how to access it. If not, there is little left to do. The only other thing I can think of is that the current sense circuit may be defective. Current transformers a rarely defective. It may also be integrated in the power module, depends on the make. If you post a picture of the board, I'll have a look.Good hunting.

author: Halvmand
author_rank: Regular Contributor
timestamp: May 19, 2016, 06:09:18 pm
content: I have now scoured the manual for a way to reset the thing, but no luck.. I can press the reset key long or quick with no result.In the manual is says the fault can be reset: See the picture.In the paper version of the manual it says that a reset to factory settings is possible by decouple the unit press both the menu, data and jog key.I don't know what they mean by decouple, but I've tried it with or without power to the unit./RantFreaking thief that sold this thing to me said it was a new old unit, never used. But it clearly has been mounted before since the imprint from the star washers is still there./Rant off

author: Halvmand
author_rank: Regular Contributor
timestamp: May 20, 2016, 05:21:42 pm
content: I'm starting to think that a reset via the front panel is not possible, since the display at once gave me a "key disabled" message. Is this a possibility that a remote reset is the way to go?The manual on this unit is not the best I've come across.About the pictures of the board. Nothing looks suspect, it does not smell like damaged electronics and nothing is missing.If you really think pictures will help i will provide them. Thanks for the help by the way.BTW. I've bought another unit (vLT 2811) which works just fine and I've had some fun with it, but that on trips the GFI at my parents house while it doesn't at my appartment.