hi friends
thanks for your replies

i have developed a resistance welding machine same as prahlad as most of people knows about his machine thats why i am using his reference,the company has done 10 sucessfull installations of machine in different organisations recently we they have installed two machine in LG plant both the machines are not working properly there
but they are working perfectly when we shift them to other industrial enviorment only problem is with LG's plant as there is lot off inductive switching in LG's plant due to very big production chain.
when we observe the firing pulse it is totally out of order no matching with zero crossing or some time even there is no pulse train.
we are unable to study it deeply as LG's production manager not allowing to do so we have repalced digital panel with analog one so that they can continue with their production.

one thing is clear that it is noise from enviorment but which type of noise it is and how to remove it.

with regards
kuldeep