windlass breakers

Ron20324 · Dec 15, 2017

the 150 is probably a slow-blow if it's like mine. Is the 200 the only other fuse between the battery and windlass.

dlochner · Dec 15, 2017

Different fuses and breakers have different profiles for breaking the circuit, some fast, some slow. The Blue Sea Systems website has information on the fuses.

If the cumulative draw on the house bank is greater than 200 amps, it will blow even if the windlass draws much less. Add up all the electrical devices that might have been drawing current, then the surge from the windlass motor kicks in and the 200 amp fuse blows.

dlochner · Dec 15, 2017

I think the answers will be in the Time Delay Charts for the fuses (if you can read them!)
Klixon Circuit Breaker - Panel Mount 150A - Blue Sea Systems
MRBF Terminal Fuse - 200A - Blue Sea Systems

The MRBF seems to be less tolerant of over current loads than the circuit breaker.

Maine Sail · Dec 15, 2017

gettinthere said:
I wired my electric windlass with 2/0 cable, well over spec, from the house bank in the rear to the windlass on the bow. I placed a 200 amp fuse at the battery bank and a 150 amp breaker switch near the windlass. I expected the 150 to trip before the 200 but it did not. The 200 has blown. Why? Nothing else on that fuse.

And of course, I dont have a spare 200 and am not in easy access to a store right now. Considering bypassing the fuse to 'get home'.

Check for a short somewhere between the fuse and breaker.. A 200A MRBF should not blow before a 150A breaker on a windlass. A 200A MRBF can handle about 300A for upwards of 100 seconds or more. if you were in there with a wrench a fuse at the battery end could easily have been fried and you may never even know you arced a wrench..

Maine Sail · Dec 15, 2017

gettinthere said:
40 foot run buried in the bilges. Crap.

If you bypass it touch the lug lightly to the busbar and if it sparks you probably have a short. If it starts to get warm, with light pressure to the busbar, and no load, you definitely have a short. Hopefully not and hopefully something just temporarily rubbed a terminal. Some of the terminals in these windlass are so close together it is not only ridiculous but it can also be dangerous. I often have to trim lugs narrower to even get terminal boots on between the lugs. You do have terminals boots on the windlass and contactor..??.

SG · Dec 15, 2017

If you have short between the battery fuse and the windlass, you can generate a lot of heat without tripping the breaker. I was warned when I suggested locating a battery nearer the windlass that that the line TO the bow can turn into a heating element that will get VERY hot without blowing a fuse. It becomes a linear heating element.

You should see no current when the windlass is not engaged.

The safe situation is to keep the windlass circuit OFF as close to the batttery as possible when you don't need it.

If the wire wasn't tinned, (especially non-marine or normal welding cables) they can get corroded because the insulation is not air inpermiable. Then there is resistance in the cable. The smaller the diameter of the cable, the more likely that a "skimming" of corrosion will degrade the capacity (surface area vs. cross section)

Xanthus · Dec 18, 2017

Maine Sail said:
Check for a short somewhere between the fuse and breaker.. A 200A MRBF should not blow before a 150A breaker on a windlass. A 200A MRBF can handle about 300A for upwards of 100 seconds or more. if you were in there with a wrench a fuse at the battery end could easily have been fried and you may never even know you arced a wrench..

h

MS is correct, that 200 amp will usually handle 300 amps for 100 seconds when new, HOWEVER, the fuse damage curve at 150% is at 2 seconds so if this fuse has seen currents of 300 amps in the past for >2 seconds it may no longer hold that current for 100 seconds. The breaker mentioned trips between 8 and 10 seconds at 300 amps so there is an overlap. This is a problem.

I would make the fuse 300 Amps. AND, I would always carry spare fuses for all applications.

Maine Sail · Dec 18, 2017

gettinthere said:
New install with Anchor 2/0 cable bought from MS, so corrosion should not be an issue.

I did get one spark when using a screw driver to connect buss pos to the windlass pos but cant get it to repeat.

MS, IIRC you suggested I could run the neg to the engine block. So negs are as follows...
Alt neg is 1' of 1/0 wire to the engine block
House neg is 1/0 cable on a stud on the starter with a run to the house buss of about 15'
Windlass neg is 2/0 to the same stud on the starter

Thanks

If you ran the windlass 2/0 to the engine block where it then picks up 1/0 the only issues wold be a bit more volt drop at the windlass motor than if you had 2/0 the entire run. The other issue is the max ampacity of the fuse for 1/0 is lower than it is for 2/0. Still you were well within range with the 200A fuse. You can easily go to 250A or 275A on the fuse but you should not be nuisance tripping a 200A MRBF with that windlass. Where are you guys? I can send you more fuses..