Lightning Protection for 400hz GPE at an airport.

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jphmeyers

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I have a similar question but it's regarding some 400hz generator
equipment that is pad mounted by the planes to supply power when on the
ground. I've not had a lot of familiarity with this equipment other than the
normal wiring connection to the electrical systems. They have told me since
I have been there that they have experienced a lot of costly equipment
failures due to lighting related incidents. There is an Equipment ground
conductor going to the ground at the main switch and 100' plus of
underground steel conduit bounded to the disconnect cabnet at the equipment.
I'm wandering if a ground grid should also be placed around the equip. and
bonbed to the cabinets as well?
 
First, you need to determine if the equipment is actually being struck by lightning and/or if it is experiencing surges do to nearby or other objects struck on the property.

If the equipment is being struck, a lightning protection system involving air terminals, down conductors, and a grounding system will help reduce the damage potential from the stroke.

If the equipment is receiving a surge via its supply conductors, a surge protection device needs to be installed at the feeder source and at the equipment.

The best advice is to layer your protection with and LPS and surge protection equipment.
 
You didn't say where the equipment failures were, so;,,,
On the primary (motor) side of the M-G , failures would be stator lead arc-overs, governor failures, bearing failures from fluctuating drive voltage, etc. If fed from ungrounded 480v, (delta), there is a possibility of very large transients during normal operation, as most of the loads are intermittent duty, that share the power source with the M-G.

On the secondary side are airplanes and stuff. Very important to make sure
the generator secondary is bonded as a derived service. Also bear in mind that the aircraft fuselage is the neutral conductor (to save weight, no, really!) Therefore any current leakage from any other powered unit also electrically attached to the aircraft can be a source of damage.

good luck,

madmike
 
400hz grounding question ??

400hz grounding question ??

As I'm aware of the situation we have experienced most of our problems with the Pulse Width Modulation Converters and they are the Jetpower Make.
We also recently installed 6 Hobart solid state Converters this year that haven't gone thru the storm season yet. The failures I'm getting from our maint. dept after a serious Lightning Storm is loss of control boards, SCR's Cap., and Chokes. Since the information I've recieved tells me they do not have a good ground grid system that's why I was wandering if ground rods or a ground grid needed to be installed at each of these stationary locations.
Thanks for any info.
 
I think it would be best to consult with the equipment manufacturers and perhaps a couple other airport authorities. This type of equipment and its use is so specialized that everything involved must also be very specialize.

I had the opportunity to visit the SW Florida International Airport while it was under construction to see the LPS installed on the terminal buildings and 3 level parking garage. Though the LPS was conventional in the code sense of the word, there ws nothing conventional about it...
 
Just to add another opinion...The military developed most of the GPU's around and considering how thorough they are there might be a mil spec for permanent installs. It's sure to be overkill. Alot of declass stuff is available online so benefit from some of your tax dollars.
 
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