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micksulley

Jul 2, 2018
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Jul 2, 2018
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I have a control system built on Maxim 1-wire technology and have been experiencing random failures for a long time. Having done loads of investigation and trial fixes I am now fairly sure that the problem is caused by noise from a soft start unit on a pump and I would welcome suggestions as to how to reduce/eliminate the noise. Either an off the shelf unit or a design for me to build would be fine.
The motor is 240v 0.82KW (0.75HP) and the soft start is United Automation SSC, spec sheet attached.
Thanks
Mick
 

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kellys_eye

Jun 25, 2010
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What form do your failures take? Have you implemented the 1-wire control using the recommended cabling etc?
 

micksulley

Jul 2, 2018
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Jul 2, 2018
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The 1-wire is a Raspberry Pi with a Sheepwalk Electronics RP3 adapter giving 8 busses. There are multiple devices on each bus. The details vary but I see one or more busses fail to respond, the only way to recover is to power cycle the 1-wire adapter. I have been investigating this problem for a couple of years now, it can be months between failures, can be 24 hours. I have changed most of the components and cabling, and feel sure that it is all OK. It has only recently occurred to me that the problem started at roughly the time I fitted the soft start, can't be more precise that a few months unfortunately. Also the failures are more frequent in hot weather, and the pump starts in response to heat from solar panels, so will start more frequently in hot weather.
 

kellys_eye

Jun 25, 2010
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but I see one or more busses fail to respond
so the fault can't be located to any one buss? Have you tried disconnecting the soft start to see if the situation improves? I'd expect any issues to be far more regular if it was the soft start as the problem.

I think a more common source of the issue is the Sheepwalk Electronics RP3 adapter, given that the fault can be instigated by devices on 'any' buss. The SE RP3 being common to everything.

Check its power supply circuitry first - potential dry capacitors problems etc.

The only real way to resolve this would be to use some form of data monitoring on the PSU and data laines to try to capture any fault event.
 
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