Getting rid of the relays

[Lou C]

Same with the fuel injection salesperson. He came through the auto and outboard motor industries and EFI replaced carburetors.

Ahh no it was the un-elected EPA bureaucrats who forced that.

 

[tpenfield]

I found the info I have on the actuator (from when I bought the boat)

Thomson Electrak GX DC 12-10A5-30

It was originally thought that the actuator was bad, but it turned out to be the relays . . . But I recorded the actuator P/N in case I needed to order one.

 

[dingbat]

We've gotten rid of all mechanical relays over the years and replaced them with Solid State Relays (SSR)

You could use 2 single relays or go with a purpose built DC motor reversing solid state relay

 

[Scott Danforth]

Put a TVS diode across the two motor leads

McMaster-Carr

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www.mcmaster.com

 

[tpenfield]

From the wiring diagram, it looks like the main power feed for the sunbed is 10 AWG and the motor feeds are 12 AWG. So, call it 20 amps. The relays are 40 amp rated, so more than adequate, but I'm thinking not right for the environment (maybe).
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If I re-wire, I'll probably just need to replace the wiring from the helm switch to the relay box (which could become more of a junction box).
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I don't have the diagram that goes to the helm switch, but I can probably figure that out from the numbering that each wire has (a godsend).

 

[Scott Danforth]

Ted,

I am willing to bet its not a capacity issue or environment issue. however that its an arc-flash contact burn issue.

we have 250 amp contactors that were taken out with two 12 amp motors because of arc flashing over the contacts after about 300 cycles during a endurance test.




this problem went away with the addition of the TVS

we literally just cleaned up the contacts with 400 grit, put the contactors back together and have now used them for well over 40,000 cycles with the TVS

here is a common 20 amp reversing switch operating a linear actuator that draws 6 amps at full load. the contacts arc flashed over, the one connection got hot and the switch failed.



pull the cover off your relay, look at the contacts. I will bet a really good chocolate stout that the contacts are simply arced over.

 

[tpenfield]

@Scott Danforth . . . Probably, the only thing is that the sunbed gets used maybe twice in a season, when it is working. I fixed it in 2022 and then by 2024 it was not working (again).

I like the TVS idea, which should work with either wiring approach. It also looks like the 30" actuator is no longer part of the Thomson 'GX' product line . . . So, if an actuator is needed, I may be getting a look-alike unit.

 

[Scott Danforth]

Get me the dimensions of the actuator. There are hundreds on the market