Ok, ive posted a thread about this before and i did get a lot of good information but most of it was aimed towards dirty electric from the power company. Let me explain what is going on and i would like some knowledgable people to help me reolve this once and for all.
The problem :
We own around 20 CNC lathes and mills, most are built from mid '90s up to just a few years old and run on 3-phase 240V high leg delta. The oldest are early '80s model horizontals which are running on 3-phase 480V high leg delta. They all experience the exact same problem. We constantly have power supply and control boards blow when powered up in the mornings. No rhyme or reason to it, all machines we own have this problem. And it is extremely rare for us to have a board blow while running a machine during the day. It ALWAYS happens when the power is switched on in morning power up. The machine will be running fine the day before when it is powered off and the next morning when it is powerd up it will have alarms when the control boots up and a control board will be at fault. What is blowing on the boards the majority of the time is capacitors, volt regualtors and usually some micro chips that are in the same cuircut as the cap and regulator. My maintenance man is the busiest man in my shop trying to keep up with replacing the bad board components. In the last 15 working days we have had 7 control boards blown during power up. When the weather changes from warm to cold we are plagued by this phenomena for about a month or so and then it will settle down and we only have a few a month brake down. When the weather changes back to hot we will experience a high rate of brake downs again for about a month or so.
What we have tried to resolve this problem:
I have had surge protectors installed in every machine. No difference.
We installed ground rods at every machine. No difference. Rods have since been removed.
We tried using E-stop pushed in when turning machines off and not taking it off of E-stop until the machine is powered completely up in the morning. No difference.
Checked that all machines have a ground wire going from the control box to the ground wire coming in from the utility pole outside. There are a few machines that currently dont have a groudn wire hooked up but all machines grounded properly or not experience the same problem.
I have been told that placing a MAINS RATED capicitor at each machine might help our situation. I would like to try this but i am not experienced enough to know how to go about this. My maintenance man isnt sure what exactly a mains rated cap is or how it should be installed. Can someone please point me in the direction of how to do this?
In my opinion this is not a dirty electric problem, if it were i would expect to have problems during the day when the machines are running which is extremely rare for us.