possible static detection/troubleshooting.

[Temper]

I work in a lumber sawmill/planer and we have a couple areas where operators are complaining about static shocks.

At the outfeed of the planer, the planermen stop an outfeed belt and run one piece through onto the stopped belt, where they grab the board and place it on top of the metal conveyor. They tell me they often get shocked. This conveyor is welded to the building framework and bolted directly to a cement pad. I added some additional bonding to try to drain any static generated by the belt, but I can't even prove that it is the belt that is the main cause.

Now I'm also getting some complaints from the grade stations which are over 100' away. Operators stand on rubber mats and flip boards all day, and get shocked when they touch handrails sometimes.

I'm worried that this is more than just static, could it be something else? The mill is a 480v floating delta and as most sawmills, has evolved over the last 50 or 60 years.

My boss is asking me to bond the grade stations now. I personally don't think this is going to help. I'm leaning towards a need for more ground plates or possibly a bad/corroded ground connection from an mcc or transformer to earth ground.

 

[Gage]

Are they getting the shocks when they touch metalwork or just before. And also is there anything nearby that could be emitting a substantial EMF. And check the voltages at Earth/Ground/Neutral. Until you know otherwise bond your life away.

 

[ifindoubtdont]

This may be long shot, but have a look on google at "Van De Graaff Generator". If all your lumber is being moved around on conveyor belts this may be the answer. You would know the difference between a static shock and a belt from 480v.

 

[Outspoken]

Could I also suggest that you check their footwear is rated as "ANTI-STATIC", it is possible the shocks they feel are not generated by the equipment but by them and the metalwork is simply providing a handy path to earth..thus giving them a tingle...seen it so many times i would be able to retire if I had £1 for every person involved..

 

[Knobhead]

This may be long shot, but have a look on google at "Van De Graaff Generator". If all your lumber is being moved around on conveyor belts this may be the answer. You would know the difference between a static shock and a belt from 480v.

Friday night. Which planet are you on?

The simple answer is to ground each part of the M/C by cross bonding.

If the shocks are from the blade:
a/ you’ve lost you’re fingers
b/ the Wimshurst effect.