A question came up today I am not sure how to address. There is a project with two 2.0MW emergency generators installed (parallel) the exhaust stacks due to dispersion analysis are routed approx. 15?-0? above the roof deck the lightning protection provided an air terminal on the generator stack with a conductor (downlead) to the rest of the system. It has come into question that if lightning strikes the air terminal current will be sent thru the generator via the exhaust stack and destroy the operating condition of the generator? Has anyone come across this when I spoke to the gen. manufacturer they have never come across this the only thing I can think of is to isolate the air terminal form the stack to provide a ?Cone of protection? around the stack and mount isolators to keep the lightning protection not in contact with the exhaust stack? What about flash over? Then I thought what about a non conductive expansion joint but the heat would probably destroy that? Any suggestions? Has anyone come across this issue previously if so how did you deal with it. thanks.
Generator Protection?
- Thread starter Mike01
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A question came up today I am not sure how to address. There is a project with two 2.0MW emergency generators installed (parallel) the exhaust stacks due to dispersion analysis are routed approx. 15?-0? above the roof deck the lightning protection provided an air terminal on the generator stack with a conductor (downlead) to the rest of the system. It has come into question that if lightning strikes the air terminal current will be sent thru the generator via the exhaust stack and destroy the operating condition of the generator? Has anyone come across this when I spoke to the gen. manufacturer they have never come across this the only thing I can think of is to isolate the air terminal form the stack to provide a ?Cone of protection? around the stack and mount isolators to keep the lightning protection not in contact with the exhaust stack? What about flash over? Then I thought what about a non conductive expansion joint but the heat would probably destroy that? Any suggestions? Has anyone come across this issue previously if so how did you deal with it. thanks.
ron
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The downlead will be much less impedance than the stack. Although current travels in all paths relative to their impedance, only some will be carried by the stack.
Even if you isolated the air terminal, if there was a strike, some current will flow on the stack as it is nearby.
Even if you isolated the air terminal, if there was a strike, some current will flow on the stack as it is nearby.
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