siemens micromaster 440 vfd

[loadangle]

I have a Siemens micro-master 440 vfd to control a 7.5 kw,1400 rpm induction motor.now the problem is after running for few days it stops automatically without showing any fault & doesn't accept start command for next few hours or so until i clean it with air.I have replaced the drive two times,but problem remains the same.I have checked the parameters & found them okay. For information i must tell that the drive stays continuous in operation without rest & the room is non ac & bit dusty too.So I personally think that, may be the continuous operation of drive causing some internal component of control card heated & as a result it triggers off command.please ask for details if you want any.thank you.

 

[ScottyUK]

Is the dust conductive?

 

[waross]

...doesn't accept start command for next few hours or so until i clean it with air.

Have you considered moving the drive to an area with no or little dust? Some way to keep the dust out of the drive?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

Generally of a drive overheats, there is a fault message telling you that. I take it from your description that this is not happening, correct?

One thing I experienced several times with MM440s is that if you are remotely mounting the display, such as on the door of a larger enclosure, the connector cable between the drive and display will become loose and it shuts down the drive. It could be that in your process of cleaning it, you are wiggling it again and it reconnects.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[loadangle]

first of all thanks for responding to the post, mates.
let me tell you few things...
1) the dust is conductive.
2)the vfd can not be moved in other place because it runs a screw extruder machine..bulky in size.it got to stay in lab where it is now.
3) the vfd HMI is mounted on vfd body,with no extension cable for remote mounting.
4) In the case of ABB acs series the fault message appears in case of inverter overheating but not sure about MM440.neva saw that msg.
I have also encountered a problem of loose HMI..which could be a probable cause of drive shutdown.so I have replaced the HMI with new one,but problem of automatic shutting down without alarm has not been resolved.

Recently I have experimentally removed a cable of TORQUE OUT PUT of VFD to PID controller & guess what? the machine is running okay now.
I anticipated that thing without any proper reasoning really.So now two questions are there,

1) why the vfd was stopping automatically without showing any tripping alarm?
2) how the removal of torque output of vfd to pid controller resolved the problem?

 

[krisys]

Would this be a co-incidence?

If you remove the control connection, the VFD may not perform the basic function which it is intended. Be careful!

 

[loadangle]

no dear only the torque signal to remote pid is bypassed..no issues with vfd performance.
its not co incidence by the way.I faced tripping off this vfd with HIGH torque alarm many times previously..I am just trying to find out the missing links between all those tripping & shutdown incidences occurred with this drive.