Bulb Failure

Hi, how do i wire for bulb failure indication on navigation lights ?

 

Fiber optics is the sure fire, never fail method. No electricity, no shorts, no corrosion, etc., just a length of FOC to each light bulb.

 

Volvo cars from around the 70's/ 80's (244 /245) had a very clever bulb failure system long before it became common practice.

No fancy computers reqd - it was all done with a (several) simple reed switches. The feed wire wrapped about 6 or 7 times around the reed switch to act like a coil; Bulb fails - current stops - magnetic field disappears and switch closes - lights a warning light.

Stick a suitable piece of rod in a drinking straw and wrap some #14 solid copper round with a little 2-part epoxy glue, wire one in line to each bulb, then feed the reed up the middle.

For extra bling, use a 2 way reed switch to drive red and green LED's drilled at the location of each bulb on a schematic diagram of the boat.

Whole job should be less than 10 bucks in parts - the glass envelope is sealed and less than half an inch long and 1/8 wide - damn near indestructable.

The only downside is if you later switch to low current LED Nav light bulbs - may not draw enough current to flip the reed switch. Then you must re-do with many more turns.

 

Another possibility is a digital current flow meter and volt meter.
I just put one in and it measures 1 to 200 amps.

I noticed when I flip on the nav lights, the meter detects the amp flow. So I imagine less or busted bulbs would mean less flow and that would show up on the meter. So figure out what it should be with all bulbs on and if a bulb quits, turning on the circuit will show it, but not which bulb is out. LED bulbs likely wont register on the meter.

This is it here. I like the display.
I found it to be accurate compared to my hand meter. And it has 2 little pots for fine tuning. The display is easy to read and bright.
http://www.ebay.com/itm/171460731501

I put the shunt on the negative bus bar for all the house circuits. So starter or inverter is not measured.
I simply undid the bolt for the return wire to batteries and attached the shunt to the buss bar. Then hook the return cable to other end of shunt.
The amp meter is like a volt meter, and polarized, so get its 2 wires reversed and just reads zero. It works well and is fun to see how much current various devices draw.

200 amp better than 100 amp, the shunt wont get so hot.

 

I should have asked the obvious question - Why?


Do you regularly moor near high traffic area and cannot risk your anchor light failing?

Are the local authorities administering heavy fines?

Are you simply looking for a better way to do things?

Or is the crew getting tetchy at being woken up at 2am and ordered to report on illumination status of running lights...

 

China Classification Society and Bureau Veritas requirement for high speed passenger ferry.

 

Ah, so ideally you need a bulb failure to generate an automatic fault condition.

Fibre Optic is more of a passive monitoring, though you could use it to trigger photo-diode detectors, there is also a risk of nuisance ambient light, e.g. if running in lower vis conditions e.g. heavy rain / mist/ fog, where the lights should be on - but the daylight levels of light can give an OK for a failed bulb.

Given it's a high speed ferry, you're going to be on AC so you could measure the current for each light using a snap on current detector - off the shelf and UL rated;-

One on each circuit (i.e bulb) and an off the shelf PLC controller to generate fault condition.




Is that nearer to what you need?

 

If there are only 3 or 4 lights, then have 3 or 4 current flow meters.

Or how about adding in a device in series with the lamp to be part of the current flow? So that lack of current current flows trips a relay which turns on a failure light. The magnetic reed relay mentioned earlier sounds useful.

May even exist some kind of semiconductor device that can do that.
Here are some, I did a search for current flow switch relay

http://www.dwyer-inst.com/Product/ProcessControl/CurrentTransformers-Switches/SeriesSCS
http://www.veris.com/Category/Current-spcMonitoring.aspx

How about asking your question on this forum, they are very good.
http://www.allaboutcircuits.com/

 

I haven't a clue what the requirement is, but one way of doing this is to use a selector switch to interrogate status before you leave the dock. This doesn't provide a warning of a failure when it occurs, but it does let you know before leaving the dock as long as you do the test. This setup is in parallel to the nav lights switch, and only works with the nav lights off. It has the advantage that it can cycle through as many circuits as you like using a single current detector and single indicator, and that it requires an operator interrogation, rather than relying on the "no fault indicated so I must be fine" theory of responsibility avoidance. It's old school, but I prefer manual interrogation for these things. It all depends on the overall repair concept (and the spec)

If the craft has dual nav lights, are you going to be doing the repairs on a fast ferry while underway or wait until you get to the dock?

 

Well thanks everybody for your idea's, to be honest fibre optics sounds the way to go.

 

Yeah, a single length of FOC, aimed directly at and in close proximity to the bulb is simple, fool proof and doesn't require anything else, such as current, additional bulbs, electronics, doesn't corrode, etc. I'd recommend you just buy a roll of bulk cable (single zip cord) which is about 30 cents a foot.