Windlass solenoids

[Zing]

I found Albright International in Hamshire who specialise in High Current Contactors very helpful for replacement of a Bow Thruster Reversing relay. They were reasonably priced as you're dealing direct with the manufacturer. I think that you can purchase the actual contact parts as a kit from them and rebuild yourself.
Kinsale 373

Yes you can. Here is where I bought from for the future use of others. I realise the OP is sorted out:
Albright SW88 Assembly Components | Separate SW88 Parts

 

[JAH]

interesting, first time I see such a comment.
Can you suggest what size (F/Ohms/W) and rating should be?
any diagram would be welcomed.

cheers

V.

PS. see you're a new poster, just be aware you will have to wait for sometime before posts are approved/accepted and appear

Sorry for the delay in responding: refitting my Shrimper before summer arrives is taking a lot of my time.

This issue turned out to be a bit more complicated than I expected. The obvious, traditional approach is to fit a non-polarised capacitor (metallised film type) and a high-current resistor (carbon composition type) connected in series across the motor terminals. This is preferable to connecting across the relay contacts as it avoids radio-frequency interference (RFI) emanating from the power cables between the motor and the relay.

The proper way to calculate the values of those components requires knowledge of the resistance and inductance of the motor. Unfortunately I found that neither Lewmar nor Lofrans include these parameters in their published specs.

An alternative “rule-of-thumb" approach is that published by C.C.Bates in 1966 using the two formulae - C = I2 / 10 ; Rc = Eo /[10I(1+(50/Eo))] where Rc is the circuit resistance, I is the operating current, and Eo is the supply voltage. However, this just gives a starting point. The selected components should be fitted in situ and the resulting voltage waveform measured on an oscilloscope, and the component values adjusted to get a peak voltage low enough to avoid arcing of the relay contacts. I think this is beyond the scope of DIY for most people.

Another alternative is to use a bidirectional transient voltage suppression (TVS) diode. These have become affordable in recent years. This is connected across the motor terminals; as before this is preferable to connecting across the relay contacts, to minimise RFI. I have identified a couple that are stocked by CPC Farnell (I have no connection with them) –

For a 12 volt system, Littelfuse SLD 24-018 gives a reverse standoff voltage of 24v and a max peak current capability of 130A, at £4.

For a 24 volt system, Littelfuse 15KPA33CA gives 33v and 276A respectively, at £11.

You can find them, and links to their data sheets, here – https://uk.farnell.com/w/c/circuit-...ctional&sort=P_ATT_BASE_VALUE_1010226_EN_GB|1

I hope this is helpful. Before fitting anything, it would be prudent to consult the manufacturer of the windlass and relay, to get their views. I have it in mind also to ask Paul Rainbow to take a look at my suggestions, as I get the impression from this forum that he has a lot more experience of marine electrical systems than I do.

 

[PaulRainbow]

Sorry for the delay in responding: refitting my Shrimper before summer arrives is taking a lot of my time.

This issue turned out to be a bit more complicated than I expected. The obvious, traditional approach is to fit a non-polarised capacitor (metallised film type) and a high-current resistor (carbon composition type) connected in series across the motor terminals. This is preferable to connecting across the relay contacts as it avoids radio-frequency interference (RFI) emanating from the power cables between the motor and the relay.

The proper way to calculate the values of those components requires knowledge of the resistance and inductance of the motor. Unfortunately I found that neither Lewmar nor Lofrans include these parameters in their published specs.

An alternative “rule-of-thumb" approach is that published by C.C.Bates in 1966 using the two formulae - C = I2 / 10 ; Rc = Eo /[10I(1+(50/Eo))] where Rc is the circuit resistance, I is the operating current, and Eo is the supply voltage. However, this just gives a starting point. The selected components should be fitted in situ and the resulting voltage waveform measured on an oscilloscope, and the component values adjusted to get a peak voltage low enough to avoid arcing of the relay contacts. I think this is beyond the scope of DIY for most people.

Another alternative is to use a bidirectional transient voltage suppression (TVS) diode. These have become affordable in recent years. This is connected across the motor terminals; as before this is preferable to connecting across the relay contacts, to minimise RFI. I have identified a couple that are stocked by CPC Farnell (I have no connection with them) –

For a 12 volt system, Littelfuse SLD 24-018 gives a reverse standoff voltage of 24v and a max peak current capability of 130A, at £4.

For a 24 volt system, Littelfuse 15KPA33CA gives 33v and 276A respectively, at £11.

You can find them, and links to their data sheets, here – https://uk.farnell.com/w/c/circuit-...ctional&sort=P_ATT_BASE_VALUE_1010226_EN_GB|1

I hope this is helpful. Before fitting anything, it would be prudent to consult the manufacturer of the windlass and relay, to get their views. I have it in mind also to ask Paul Rainbow to take a look at my suggestions, as I get the impression from this forum that he has a lot more experience of marine electrical systems than I do.

My fields are electrical systems and marine electronics (as in chart plotters, radar AIS etc), rather than general electronics. When it comes to component level electronics my knowledge and experience is both limited and narrow.

My only thoughts are, what is the problem that's in need of a solution ? There will be millions and millions of boats out there with electric windlasses, winches, starter motors etc all activated by solenoids, yet we see very few issues with the solenoids due to arching. Windlass solenoids (contactors) last for years, if not decades and cost very little. Perhaps your solution will reduce arching, but will it just be extending its life from 15 years to 18 years (kind of thing).

In the last 10 years, maybe longer, i have only changed one windlass solenoid and that was a few weeks ago due to water ingress, the solenoid was probably 25 years old.

 

[vas]

JAH, thanks, have to admit it does sound complicated and I'll most likely pass!
further according to Paul above considering I cleaned the slight arching in the contactors 6yrs ago on a now 40yo boat, I'm probably fine for another couple of decades...