Home › Forums › ROV › ROV Technical Discussions › lim tripping prob
- This topic has 55 replies, 20 voices, and was last updated 16 years, 9 months ago by barrowmafia.
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February 27, 2008 at 10:59 pm #16242TheProphetParticipant
Rov whinner
Would that be Stig of Sonsub fame?February 28, 2008 at 12:30 pm #16243AnonymousGuestYep
February 28, 2008 at 12:33 pm #16244AnonymousGuestHey SteadyEddie, Lostboys one cool dude, if hes on your ROV you’re lucky. He can fly inspection ROV’s just by looking at the joystick.
Don’t mess with FarmerBoy either I heard he’s one tough motherf*%ker… ordered a Big Mac at Burger King, and got one
What a friggin Video Ray with or without the Greater Thrust Option??…….
February 28, 2008 at 12:41 pm #16245Andy ShiersParticipantYep , , Alias ‘The Womble’
He walks with two Video Rays at the hip , Dosen’t have a blind side
Well…………….. Unless he’s driving a van that is
Then , No granny is safe on the pavementMarch 1, 2008 at 11:30 pm #16246barrowmafiaParticipantHi,
Just to clear a couple of things up. I went out on this job, on seaeye marine’s behalf.When i said the LIM is not reliable, i told your back to back, that, If the LIM shows a fault, there is a 100% chance a fault is on the system. But when the LIM says no fault, there may still be a fault on the system. This has been proved time and time again.
It is wise to put in place the testing procedure into your weekly or monthly checks. This will then give you some knowledge of the intergrity of the system.
I agree with a previous poster who said they have only changed a LIM out once. The LIM is sometimes blamed because no fault has been found. Because it has not been found does’nt mean its not there.
The problem you now have is, if you have tested the system as the procedure i left, then the fault is only subsea. This will be hard to find.
I do have proir knowledge of this system and the operation. I would guess that there is tether damage, as there has been a lot of tether damage in the past.
You could blank off the tether whip and tie the sub into your launch cage. Dive the sub and leave it for a while. Put tension on the tether and unplug the deck lead from the surface unit and megger the tether.
If this passes then it has to be on the sub. You have already found cables that have been cut. Inspect every cable.
Then i suppose you will have to open the e-pod and dissconnect one node at a time, dive the sub and monitor the LIM. Repeat until the LIM is Stable.Remember the LIM is a protection device not a test instrument.
I will speak to seaeye on monday to see about meggering the system while it is in the water, then you could slowly bring the system up and monitor the insulation resistance as it rises out. I don’t see why you can’t do this but i will speak to nick to be sure.
My gut feeling is the tether, as pressure related faults are less common and from what i saw, damage is the favourite.
Im home now for a few days feel free to contact me. Your company has my details.
March 1, 2008 at 11:34 pm #16247barrowmafiaParticipantP.S
It was working when I left it, honest…
March 2, 2008 at 1:22 pm #16248SavanteParticipantgood to see seaeye paying attention to the boards!
March 2, 2008 at 9:27 pm #16249Ray ShieldsParticipantP.S
It was working when I left it, honest…
LoL! How often have we all said or heard that
I said it last month when I left a system One ROV pump, 2 sets of TMS control boards, one set of TMS sliprings, its working again
March 2, 2008 at 11:54 pm #16250Scott BeveridgeParticipantOnce again, it doesn’t hurt to actually test the LIM unit (Bender – right?). See manual.
March 3, 2008 at 9:56 pm #16251shandydrinkerParticipantA few things to have a look at:
1. Solder joints in the tilt platform interface pod, found in the past that the solder joints on the 5 way connector wires within the interface pod caused a Falcon DR to trip intermittently.
2. Moisture in the light nodes – remove cover, glass and disconnect pcb (3 screws) and warm up – DO NOT apply a heat gun, it will damage the board.
3. When meggering Falcon nodes make sure you join wires 1,2,3&4 together, connect red crocodile of the megger to the this group and black crocodile to wire 5(Green one) – set megger to 250V only. I have had systems trip with a megger reading of 300Mohmn. Make sure you disconnect the 2 pin tilt motor whip and feed back pot whip
4. Megger tilt motor pin 1 to case then pin 2 to case – not between the pins as this will give a direct short
5. LIM – Set both dial switches, lower left corner on the LIM, fully to the left – anticlockwise, makes the LIM less sensitive
6. Make sure the oil levels are correct in the tilt motor and feed back pot
7. As previously mentioned, check that all node whips are without damage
8. If a VOFT is fitted check that there is no water ingress in the oil – drain both VOFT and compensator clean out with electa clean and replace with new hydraulic 22 or 32 oilTry that lot – best of luck
March 4, 2008 at 10:54 am #16252shandydrinkerParticipantSorry bum info – item 5 Lim dials are in the lower right corner not the lower left corner.
March 7, 2008 at 6:45 pm #16253Andy BirchallParticipantNewbie to all this – what do you mean by "Bender" re: the LIM?
Thanks.
March 7, 2008 at 8:32 pm #16254Ray ShieldsParticipantNewbie to all this – what do you mean by "Bender" re: the LIM?
Thanks.
Bender is the name of the manufacturer of a standard Line Insulation Monitor used on many ROV systems.
March 7, 2008 at 9:15 pm #16255Andy BirchallParticipantAh.. thank you for that.
March 7, 2008 at 11:43 pm #16256deevalueParticipantSo IOMAndyB,
Is current leakage or Ground fault not on the sylybus at FW?
What do they say about isolations?
Scary questions?
I’m a newbie too, New to ROV’s but not to electronics or hydraulics for that matter. Hopefully you will be properly trained before you work with me!
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