I had started a thread on this discussion a few months ago but thought i would start a new one as the other had gotten rather large in posts to sort through and i think i now have a more narrowed down idea as to where the problem might be. Here is a link to the other post if you want to do a lot of reading. http://forums.mikeholt.com/showthread.php?t=163677 .
First a little information about our situation. I manage a small machine shop with around 20 + CNC machines. We are having on average about 3 to 4 machines blow a cuircut board every month. Obviously this is a big problem for us in many different ways.
The same problem plagues all CNC machinery whether it is new or old.
Power on and off sequence for machines is as follows.
1. Switch on all cuircut breakers inside of machine cabinet.
2. Switch on the machines main power disconnect (cuircut breaker) on the back side of machine.
3. Switch on the machines electronic control which powers on the computer electronics boards and monitor.
4. Operate machine.
5. Switch off electronic control.
6. Switch off main power disconnect.
7. Switch off all cuircut breakers.
CNC machines are blowing electronic cuircut boards. Specificly the majority of components damaged on cuircut boards is capacitors, voltage regulators, diodes, transformers. The problems appear to be occurring during the night when the machines power is disconnected from the power grid.
Facts which point to this are as follows -
- A machine will be running properly at the end of shift when it is turned off and the main disconnect on the machine is switched off at the end of the day. The next day when the operator switches on the main disconnect and turns machine control on the machine will turn on in an alarm state and will have a cuircut board damaged. This is the way that 99% of our break downs occur.
- Many times a machine will have numerous cuircut breakers inside of the machine tripped off when the operator powers the machine on in the morning. Typically there is no damage to a cuircut board and powering the machine off then switching on the breakers is all that is needed. Other times a cuircut board will have been damaged.
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- On 8/7/14 before any machinery had been turned on in the plant i personally inspected every CNC machine in the plant and found 4 machines which had at least one cuircut breaker inside the machines switched to the off/tripped position (these breakers are either on or off the tripped position is off technically).
Out of the 4 machines with breakers switched off 3 of them had been running the day before when they were powered off. All 4 machines powered up and ran fine after reseting the breakers.
- After the incident on 8/7 i instructed all employees to switch off all breakers inside of machines after they had switched the machines main power off at the end of the day. Since that time (two months now) we have not found a single machine breaker tripped off after powering off a machine. Neither have we found a single breaker tripped off after the operator switches breakers on and main power has been switched on in the morning. However we are still experiencing cuircut boards being damaged.
- IN MY OPINION THIS IS A SIGN THAT THE BREAKERS ARE NOT BEING TRIPPED OFF WHILE THE MAIN POWER IS SWITCHED ON OR OFF BUT RATHER THE BREAKERS WERE BEING TRIPPED AT NIGHT WITH NO CONNECTION TO THE MAIN POWER GRID. I understand this is almost impossible but this is what is happening and the facts dont lie.
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Have installed surge protectors on most machines. Saw no difference in problems.
Have installed electric filters on most machines. Saw no difference.
Have switched from 240V high leg delta to 208V WYE power. Saw no difference.
Have installed ground rods for machines and later disconnected ground rods. Saw no difference.
Another bit of information that may or may not be connected to the problem is that we are located on property where an old foundry was and the ground here is terribly poluted with tons of metal in the ground. And also from what i have been told there are numerous acid pits here that were simply covered over with soil when the foundry closed a long time ago. One of our CNC repair companys recently told me that we are sitting on top of a battery. That may be a little dramatic and may or may not be the case but i suppose it could possibly have something to do with our trouble.
I am currently looking into moving our business but that is a huge cost and i would certainly like to stay where i am if its at all possible. This problem is so weird i do not know who to call on to diagnose it. Most electric people simply do not believe what i am telling them.
Anybody know of a lifeline i can call.
First a little information about our situation. I manage a small machine shop with around 20 + CNC machines. We are having on average about 3 to 4 machines blow a cuircut board every month. Obviously this is a big problem for us in many different ways.
The same problem plagues all CNC machinery whether it is new or old.
Power on and off sequence for machines is as follows.
1. Switch on all cuircut breakers inside of machine cabinet.
2. Switch on the machines main power disconnect (cuircut breaker) on the back side of machine.
3. Switch on the machines electronic control which powers on the computer electronics boards and monitor.
4. Operate machine.
5. Switch off electronic control.
6. Switch off main power disconnect.
7. Switch off all cuircut breakers.
CNC machines are blowing electronic cuircut boards. Specificly the majority of components damaged on cuircut boards is capacitors, voltage regulators, diodes, transformers. The problems appear to be occurring during the night when the machines power is disconnected from the power grid.
Facts which point to this are as follows -
- A machine will be running properly at the end of shift when it is turned off and the main disconnect on the machine is switched off at the end of the day. The next day when the operator switches on the main disconnect and turns machine control on the machine will turn on in an alarm state and will have a cuircut board damaged. This is the way that 99% of our break downs occur.
- Many times a machine will have numerous cuircut breakers inside of the machine tripped off when the operator powers the machine on in the morning. Typically there is no damage to a cuircut board and powering the machine off then switching on the breakers is all that is needed. Other times a cuircut board will have been damaged.
______________________________________________________
- On 8/7/14 before any machinery had been turned on in the plant i personally inspected every CNC machine in the plant and found 4 machines which had at least one cuircut breaker inside the machines switched to the off/tripped position (these breakers are either on or off the tripped position is off technically).
Out of the 4 machines with breakers switched off 3 of them had been running the day before when they were powered off. All 4 machines powered up and ran fine after reseting the breakers.
- After the incident on 8/7 i instructed all employees to switch off all breakers inside of machines after they had switched the machines main power off at the end of the day. Since that time (two months now) we have not found a single machine breaker tripped off after powering off a machine. Neither have we found a single breaker tripped off after the operator switches breakers on and main power has been switched on in the morning. However we are still experiencing cuircut boards being damaged.
- IN MY OPINION THIS IS A SIGN THAT THE BREAKERS ARE NOT BEING TRIPPED OFF WHILE THE MAIN POWER IS SWITCHED ON OR OFF BUT RATHER THE BREAKERS WERE BEING TRIPPED AT NIGHT WITH NO CONNECTION TO THE MAIN POWER GRID. I understand this is almost impossible but this is what is happening and the facts dont lie.
_____________________________________________
Have installed surge protectors on most machines. Saw no difference in problems.
Have installed electric filters on most machines. Saw no difference.
Have switched from 240V high leg delta to 208V WYE power. Saw no difference.
Have installed ground rods for machines and later disconnected ground rods. Saw no difference.
Another bit of information that may or may not be connected to the problem is that we are located on property where an old foundry was and the ground here is terribly poluted with tons of metal in the ground. And also from what i have been told there are numerous acid pits here that were simply covered over with soil when the foundry closed a long time ago. One of our CNC repair companys recently told me that we are sitting on top of a battery. That may be a little dramatic and may or may not be the case but i suppose it could possibly have something to do with our trouble.
I am currently looking into moving our business but that is a huge cost and i would certainly like to stay where i am if its at all possible. This problem is so weird i do not know who to call on to diagnose it. Most electric people simply do not believe what i am telling them.
Anybody know of a lifeline i can call.