Indramat TVR3.1 mains fault 1

[cccelcj]

I am having a very hard time figuring out what is going on with an Indramat TVR3.1 regenerative power supply that keeps giving me an "04" fault, which is a mains fault. This is just a shot in the dark as there may not be many users of this kind of equipment. I have changed out the supply two times already. Unless the supplies I have changed out are bad, I cannot figure out what is the problem. The service manual states there are three reasons this fault can occur. 1.) Low voltage. 2.) Open fuses 3.) Missing phase. I have ruled out these possibilities. Can anyone give direction?

 

[motorsdirect]

hi
Have you considered the possibility of voltage drop when the unit is working on load???
just a thought..
Jeff

http://www.motors-direct.co.uk

 

[cccelcj]

Yes, Ihave considered trying to lay my hands on some type of recorder. Am currently seeking to borrow a hand-held Fluke scopemeter. I measure with a DVM 455VAC on all three legs. Of course, this kind of instrument is inadequate to measure any kind of transients or fast occurring fluctuations. Is there any clear cut way to measure voltage drop?

 

[motorsdirect]

I have seen units that plot volts and amps constantly,on all phases..these would be ideal. but I am not fortunate enough to have one to hand!..
What are you driving with this unit??? And how often does it go out on fault??

Jeff

http://www.motors-direct.co.uk

 

[cccelcj]

This is a regenerative power supply that rectifies three phase AC and develops a 300v dc bus voltage that is used by 3 servo drives. These servo drives control two 11kw ac motors and an one 15kw motor with digital encoder feedback. This problem is very random, but generally occurs after the equipment is stopped and then restarted again. Upon attempting to restart the display on the supply goes to the dreaded "04" fault code, which is a mains fault.

 

[motorsdirect]

Then I think maybe we could be looking in the right place,being that voltage drop is far more likely to occur when a high startup current is required.

Jeff

http://www.motors-direct.co.uk

 

[rawelk]

I am in the middle of a similar experience with an Indramat KVR supply, and it looks like there are two different effects at work.

First, the circuit breaker protecting the mains (1V1, etc) is trip curve B, and it sometimes trips on power-up (perhaps every 10 or 20 power-ups). I'm going to replace it with a trip curve D breaker which can handle the inrush currents. An '04' mains fault caused by the breaker tripping happens immediately.

Second is a mains fault that occurs after approximately 4 seconds and the power supply has finished initializing. In this case the trip happens very much more frequently when a 400 HP DC drive on an adjacent production line (and derived from the same bus) is running, and appears to be related loosely to that motor's speed. If the power supply makes it past the initialization phase then it'll run fine, and doesn't trip out in operation.

Used a Scopemeter to observe an AC line to ground at the KVR, and find there is a healthy commutation notch smack dab in the middle of the sine wave peak.

My guess is the commutation notch is messing with whatever algorithm Indramat uses in their mains detection routine, and triggering the spurious fault.

There already is a line reactor interposed between the bus and DC drive, so I'm planning to install an isolation transformer for the Indramat supply.

 

[blacksea]

I had similar problem for other servo amp with three phase AC supplying (with internal rectifier). The cause of the same fault as one phase lossing was high sensitivity to phases' unbalance for three AC wires without neutral one. The suggestion of manufacturer was masking of this fault!
Pls contact at Indramat for the same solution.

 

[Drivesrock]

Dear cccelcj, I think you may find that one of the servo drives has a fault. Does your drives arrangement have a type of flat-ribbon cable across them paralleling some 24V and other signals? One of the drives is causing the 24V line to drop and this causes the rectifier to trip on mains fault. This would explain why you have changed out the rectifier twice and not solved the problem.
I am trying to remember properly but is there also a trimpot on the power supply?

Drivesrock

 

[machmech]

Hello Drivesrock

Are you suggesting that induction could be causing interference within the cable ?

 

[machmech]

Opps Sorry ment to type inductance!

 

[Drivesrock]

No, there may be a problem with one of the drives.

 

[rawelk]

In this specific instance the connected drives are "faultless", and the control DC supplies (available through the daisy-chain ribbon cable) are good - within voltage tolerence, and with acceptable ripple levels.

I have a copy of the "before" waveform (previously mentioned; the one showing a big commutation notch). Once the isolation transformer has been mounted and wired I'll save an "after" waveform, stick both into a PDF, post it to my personal web space, and plonk a URL to it in this thread. My guess is that the spurious mains fault will go away once the isolation transformer is supplying the KVR ... if my guess is wrong I'll post that here, too .

When the two lines using these Indramat drives were first installed we had a somewhat similar problem with the servo power supplies for the trimpress, except that, in those cases, the power supplies would puff the blue smoke of death.

This problem went away after adding a 3% line reactor to the 400HP DC extruder drives, and installing isolation transformers for the press servo supplies.

My best guess, in that case, was that a press power supply (which has two axis with fairly fast start/stop motions, and another servo swinging the cutting platen) would see the line notch go down all the way to 0 volts, figure it was zero-crossing (and OK to regenerate back to the line), and blue smoke when it learned differently.

The PDF docs at my disposal don't get into the nitty-gritty (no schematics; not even adequately detailed block diagrams) to answer this assumption definitely ...

 

[rawelk]

For completeness I've posted a PDF file[/LINK] with troubleshooting notes, and waveform captures to extend my post of 17 Jul 05 21:14.

Isolation transformers have been installed for a couple of months now. The Indramat KVR trip symptom went from chronic to cured immediately, and has not returned.