Method of Lightning Protection of Movable Machines on Port

<...suggest method of lightning protection for rail mounted movable machines on Port viz ship unloaders and ship loaders...>

They are the lightning conductors in themselves, though one method of providing some protection is to put a taller earthed structure in the vicinity, and hope that the lightning strikes that object preferentially.

good post above . are those grounding brushes rated for lightning or for low voltage and static earthing purposes ?

Their purpose is to brush the %$£& off the rails, so that there is better wheel-to-rail contact, which is where the earthing takes place.

That rail brush manufacturer seems to be addressing a real world need and do describe the use thus:

For ordinary crane rail surface sweeping and grounding discharging

The wheels will still play a big part for sure.

That rail really needs to be properly grounded per standards and accepted practices for this to work properly.

The other lightning risks also need to be addressed in the normal manner (see the link to the Oz standard) to achieve safety and protection in addition to the preferential energy shunting path that the rail provides.

One flash and you're ash

i think we need to validate the difference between carbon or copper brushes used to transfer current between two moving surfaces and brushes used to clean the rails

notice some of the brushes on that page have great big braided copper earth straps bolted to them for grounding

the felt ones are grease applicators

and others are purely for cleaning , not grounding

if you earth a lightning strike through the wheels you will blow the bearings to bits , admittedly the mass on the wheels will guarantee a good contact from wheel to rail but how are you proposing to make earth contact with the wheel ?

are you suggesting making the bearings sacrificial ?

take a lightning strike through the wheels and you have a grease fire that can spread and destroy your crane.

To calculate geometry try the Rolling Sphere method.

you have to use a spring mounted brush to scrape and clean the rail track and use a copper contactor or brush rated for the current running along the track , make sure there is no breaks in the track where earthed connection is not made . If its on a Jetty then the earth cable from the track has to run back to shore.

do they have slew bearings ? , if so then slip rings mounted in the center of the slew would be required like those used on wind turbines .

anywhere that has rollers needs protection for the bearings.

you would also look at isolating electronic control cabinets with rubberised mounts , and perhaps putting surge protection on the mains power cables , and on any low voltage sensor cabling such as winch position sensors or loadscale sensors.

what about the operators seat , controls and cabin ?

surge protectors are also available for two way radio antennas which they would have in the operators cabin.

you have to use a spring mounted brush to scrape and clean the rail track and use a copper contactor or brush rated for the current running along the track , make sure there is no breaks in the track where earthed connection is not made . If its on a Jetty then the earth cable from the track has to run back to shore. that will do for lightning protection.