110 Electrical Guru needed

[poppi]

Darn and here I thought checking was allowed. Was he called for high brooming?

  Warm up warm downs whoa no wonder my gens don't last....

Skip

[Sean]

Someone please educate me on the need to let the genset warm up before applying a load.

Again, I come from the boating world and it is normal practice to start the genset and hit it with everthing at once.

It's debatable just how much "warm up" is required before applying the load.  However, at a bare minimum, you want the engine to be fully started and the RPMs to stabilize first.  With no delay whatsoever, many transfer switches will close while the starter is still spinning, thus loading the engine before it has even fully started.  This puts additional strain on the starter as well as the pistons and other engine components.  Also, since voltage will not be fully up to nominal, any induction loads will actually be harder to start and draw more current, providing even more resistance and also reducing the life of those induction motors.

BTW, many marine generator installations that I have seen do include such a delay mechanism, even if it is as simple as a contactor in-line which will not close until a minimum voltage has been reached.  But almost every marine genset comes with instructions to let the generator fully start (and/or warm up) before applying the loads, so the assumption is that this will, at minimum, be done manually if there is no automatic delay.

-Sean
http://ourodyssey.blogspot.com

[paul102a3]

OK, that makes better sense. Most of the boats I have dealt with (30 to 60 feet) all have manual transfer switches so there is no issue with the genset not getting up to RPM.

Thanks for the clearing that up.

[bobofthenorth]

I must confess that when the Uke goes on one of his rants I tune out a lot - maybe all - of what he is saying.  The gist of the rant was that the block is iron and the pistons are aluminum and therefore they warm up at different rates and more importantly expand at different rates.  That meant that by putting it to work too soon I was doing something that he could detect on the pistons but beyond that I don't remember.