micromaster 420 problem

[denz52]

Hi gents & ladys
I have mm420. two motors connnect to mm420. sometimes mm420 doesnt work. no fault or no warning on BOP screen. we send to speed information from siemens touch panel to plc.PLc sent speed information to mm420 as 0-10v (terminal 3 and 2)..,mm420 sent actual value to plc from terminal 12-13 as a 0-20mA to plc.
terminal 7 for reverse,terminal 5 release and term.6 overspeed on mm420.
how can I solve this problem? plaese sent any advice..

 

[parky]

Chuck it in the bin & get a mitsi,I have had a number of issues with these & that's exactly what I have done.
but before you do, check if the run signal (sually digital input 1) is energised from the plc or other control source, you are sending the speed reference from the plc.

 

[John Gaunt]

I agree, Micromasters are nothing but trouble. I have had success with ABB in very hot and dirty conditions in southern India. I am currently in Thailand installing more ABB.
By the way, I am not anti Siemens, I use S7-400 PLC's for very precise high temperature control.

 

[parky]

Hmm.. not had much luck with AB either, we have a system that has(had) 5 ab drives, we replaced them quite frequently, as our guys know mitsi & danfoss pretty well we changed them as they failed, guess what, only had one problem since, an operator decided to wash down the panel while an engineer was wotking inside, only one suffered, these have been in now for about 18 months & work fine.

 

[John Gaunt]

Not AB but ABB.

 

[parky]

Yes AB Allen Bradley (or rockwell)