Break sensor adjusment for Lithrone 540

[Paul Bradley]

Hi I am trying to understand your problem, if there was no problem before you changed the tachogenerator, why did you change it?
The tachogenerator is a small DC generator similar in construction to a small permanent magnet DC motor, it should also have a set of carbon brushes.
The tachogenerator gives an output voltage directly proportional to its speed, ie 1 volt per 1000 revs or similar.
I suggest you check the brushes on the old tachogenerator and maybe test both using an electric drill to turn it and check the output voltage of both.
Are the nameplate output voltages of the old and new tachogenerator similar?
Is the coupling between the motor shaft and tacho generator tight and not slipping?
Have you checked the colour of the main motor commutator? it should be a nice smooth chocolate brown colour.
Good luck.

 

[komori92]

Sorry I wrote it wrong, the problem that lead us to change the tacho was when we ran the machine it increased the speed by itself, so it was running on high speed, then when we called the electrician he said it's from tacho and then we changed it for a new one with exact same specifications.
Coupling between shaft and tacho is tight.

 

[Paul Bradley]

Ok I understand.
If the original Tacho had no output then the motor would run at full speed so it must be faulty.
You will need to test the new tacho it would seem that this will be the problem.
Regarding the old tacho please check the brushes they dont usually fail for no reason.
Regarding the new tacho see if you can run this at a steady speed and check the voltage output, was this new when fitted?
It seems strange that you would have more than one fault. Did someone adjust any of the preset adjusters on the drive?
If so the drive may be hunting that may explain why the motor speed is varying at low speeds

 

[komori92]

Yes our electrician did adjust the present adjusters but he didn't take a photo of how it was. And now we are unable to adjust them.

 

[Paul Bradley]

Hi again
Can you send me a clear photo of the adjusters on the drive, from your previous photo I can see there are marks on the adjusters also there is a pot marked IRCOMP this is used if the drive is using V,I feedback is there a switch on the drive to change the feedback from tacho feedback.
If the motor is hunting then either there is a problem with the tacho or there is a problem with the feedback circuit in the drive.
Have you checked the current in the SCR bridge.
is there a company near you that sells or services DC drives? the principles are the same in most drives.
Are you sure the two tachos are the same output?

 

[komori92]

Yes I am sure that output is the same in both tacho.
Yes current is good in SCR.
I ll check if there is any company nearby that can do it.

 

[komori92]

And we have one more issue with this part of a board not working.
Sometimes it's working sometimes its not.
And we can't upload a file without these buttons.
Any help would be appreciated.
Thank a lot for everything that you are doing to help us.