380 S2: Name that Part - Alternator Edition

[twowheel]

Ok here's one....anyone have an idea what this is?

Came off of our STB alternator. Some sort of jumper harness that isn't Yanmar.

[Calif.Ted]

I believe the blue object to be a capacitor and I suspect it was a radio static suppression device.
Found a page with an explanation that may be of help, scroll down to the section on alternators.
Easy solutions to Radio Frequency Interference

[captnjbk]

That appears to be some sort of suppression device. They may have been getting alternator noise on one of the radios or electronic devices. Take it off and see if you start getting a buzzing sound somewhere that goes up and down with engine rpm.

[Cheechako]

Yep, that's a ceramic disc capacitor. Good for high voltage/ low amperage.

[senormechanico]

It also appears to be in series with a diode which makes no sense at all.
The capacitor (if that is what the blue part is) would charge and stay charged to peak voltage, rendering it incapable of any further action.
The blue part might be a metal oxide varistor which would act as a short duration transient voltage dump.

[Cheechako]

Originally Posted by senormechanico

It also appears to be in series with a diode which makes no sense at all.
The capacitor (if that is what the blue part is) would charge and stay charged to peak voltage, rendering it incapable of any further action.
The blue part might be a metal oxide varistor which would act as a short duration transient voltage dump.

Good point on the Diode, I thought that was wire but on closer inspection it's a diode. The diode is like a valve only allowing voltage one direction. Not that uncommon on some installations, but the Cap... is mounted in series which is a bit weird...

[rabbi]

Capacitor and diode in series doesn't make sense to me.

I would simply not worry until something stops working

[Shrew]

Originally Posted by twowheel

....anyone have an idea what this is?

It looks "Home Brew" to me.

[twowheel]

Hah, this thread sounds like the dialog in my brain around this thing.

What I first thought was a ceramic capacitor (blue) actually seems to be a varistor wired inline with a capacitor.

In digging around the Beneteau parts site I found what seems to be the same thing but of newer design. Now if I can just figure out the specs so I can make one...or two.

[Reefmagnet]

I'm guessing either a thermister (current limiting / auto reseting device) or a capicative coupler on an AC winding for, perhaps, the tacho input.

[gradyho]

It's an MOV, I used to use them with telemetry.
https://en.wikipedia.org/wiki/Varistor

[tim m]

It looks like a TSP-12 look on the Balmar.net website TSP stands for transient Spike Protector it is a fused diode that is designed to fail before your alternators diodes fail.

no silly quote just good business

[senormechanico]

Different name, but still the same device.
Metal Oxide Varistor, Transient Spike Protector.
The higher the applied voltage, the lower the resistance.
This happens almost instantly, thus the protection against a spike.
Definitely NOT a capacitor.

[John Lagoon 380]

This part is connected to a relay, that is connected to your Cristec battery isolator, model RCE/100-2E-3.


Both engines have the part.


The battery isolator receives the output from the 2 engines and directs it to the least charged of the three batteries.



The part excites your alternator on command from the battery isolator - because the isolator / alternator installation does not have ignition alternator excitation.


I suspect that if you remove the part, the isolator wont charge your batteries.


Note. The Cristec isolator is rated to 100 amps. Standard Yanmar alternators output 60 amps each. If you replace your engines with the latest models, these have 120 amp alternators. So now you will need to upgrade your battery isolator to cope. The engine upgrade is a nice upgrade because the new engines use a serpentine belt to drive the water pump and alternator - say goodbye to all that vee belt dust, grief, and on-going replacements. You can get parts to upgrade an old engine to use the serpentine belt.