[QUOTE=captsteve1319;86040]No, currently I am on a convetional CPP boat with electric thrusters. Thus the shaft gen comment.
I have run an all electric Z-Drive boat and on that in a high thrust condition you “could” over amp your thrusters or go into load shed. Not fun, but you have to know your equipment limits and abide by them. That vessel had 4 gensets to provide power and was always tripping 1 or 2 offline limiting you available power.
As far as Z-Drive boat tracking, they can at times be a handful, they don’t care much about the pointy end and will slide and crab. Not being a ship designer I can only guess that lack of a keel and having a very flat bottom does not help the situation.[/QUOTE]
I really hope that was a joke calling those Rigdon boats large vessels.
A good friend of mine was a technican for Alstom/ Conver team, which is the power managment system and the VFD’s on those rigdon boats, I have worked on several boats with that system and it is a pretty decent system. I run couple US flag and one big Norwegian boat with the Alstom/conver team PMS and VFD’s, never been on any of those little rigdon boats though.
The conver team PMS along with most power managment systems are designed to where if they are working properly you should in “Theory” never be able to black the boat out. I did high light theory.
When you consume roughly 95% of your available power that system goes into power limiting, in power limiting mode it cuts the power back to roughly 75% either on the entire plant or the individual thruster that you are fixing to over amperage. It is designed that way to keep the operators from over amperaging the specific equipment. Once you continue to hammer on it asking for more power, and you have crossed the threshold of 105% of your available power in power limiting mode, then and only then will the system go into load shed. It is designed to trip non essential, systems off first, ventelation, A/C’s ,pumps, bulk compressors, the thruster using the least amount of power, and on down the line to the last thruster which is consuming the most power. Load shed is the computer’s way of protecting the equipment from the operator. If you are continually load shedding thrusters either that boat is way under powered, or you are continually using 95% or more of the power available. If you are using that much power that does not sound like slow and steady to me. Granted I know shit happens randomly, that I can over look, but on a regular basis???
With that being said, If you are having problems like that, you need to get someone to come check the power managment system, cuz it obviously aint doing what it is suposed to.
If it is working correctly, I have to agree with fraqrat, how in the world did you ever get a boat with issues like that past the vetting procedure to work fot any of the oil companies. If you can trip generators off line just moving around fourchon, I don’t won’t to be on that thing next to a rig.
How in the world did you ever get it to pass a FMEA trial. I am sure the class surveyor would have a cow bieng a witness to such things.
The shaft generators with CPP wheels is a little different story, they are easier to trip the shaft generators off line. However then you should still have the main’s and hotel ganerator’s for the boat, with aleast some control. Even though you would loose which ever thruster wa being supplied by that generator. There are really only two companies that run a shat generator and CPP wheel in the gulf. Most everyone else runs straight electric plants.
Also when you are keeping the system in power limiting there should be alarms going off everwhere. You should be getting high load alarms from your generators, insuffecient power alarms from the DP console or the thruster page, not to mention everything else that is probably going on at this time.