3-phase borehole pump, relay trigger delay?

  • I bought a couple Shelly 3 Pro for automating various 3-phase pumps. During my bench tests w/ Home Assistant I notice that the three relays aren't triggering 100% simultaneously (there is a very tiny delay as the relays engage; always in the same order 1-2-3, with approx. 0.25 seconds gap in between each relay).

    I'm not sure if this is due to Home Assistant / network delays etc. causing sequential triggering... But my question:

    Is there any way to gang all the three relays together within the S3Pro firmware, and trigger all relays as *one* single device / entity (instead of three individual devices / entities)?

    Note: My concern is to avoid the (very small) risk of one-of-three relays not 'getting the message' from Home Assistant and my borehole pumps being forced to run on less than 3 complete phases. Many thanks!

    Note 2: Yeah, my alternative option is to use a single-relay type Shelly plus a 3-phase contactor (which is probably the more bullet-proof solution).

  • I would appreciate the “bullet-proof” solution too! Cheaper and more reliable…

    „Habt Geduld. Alle Dinge sind schwierig, bevor sie einfach werden!“ (aus Frankreich)

    „Nothing in life is to be feared, it is only to be understood.“ (Marie Curie, 1867-1934)

    „Es reicht nicht“, rief Schiller, „Gedankenfreiheit zu fordern, man muß auch denken können, sonst fordert man Gedankenlosigkeitsfreiheit und die ist die Freiheit zur Dummheit, welche wiederum die schlimmste Unfreiheit überhaupt ist!“
    (Aus „Besuch aus Weimar“ von Gert Heidenreich, Schriftsteller, *1944 in Eberswalde)

  • I would appreciate the “bullet-proof” solution too! Cheaper and more reliable…

    Not sure if a 3 phase contactor + 1 Shelly is indeed cheaper than a S3Pro these days! All my local electrical shops are selling ABB, Hager, Schneider, Legrand etc. etc. brand DIN 3-phase contactors for anywhere from EUR 60~120 depending on spec. But I'll probably go this route all the same. Pulling up a broken borehole pump from 200m+ is a huge pain and definitely more expensive than a contactor :)

  • Oh, that’s not really a bargain. Had the cheap Polish/Chinese contactors in mind while giving my guess…

    „Habt Geduld. Alle Dinge sind schwierig, bevor sie einfach werden!“ (aus Frankreich)

    „Nothing in life is to be feared, it is only to be understood.“ (Marie Curie, 1867-1934)

    „Es reicht nicht“, rief Schiller, „Gedankenfreiheit zu fordern, man muß auch denken können, sonst fordert man Gedankenlosigkeitsfreiheit und die ist die Freiheit zur Dummheit, welche wiederum die schlimmste Unfreiheit überhaupt ist!“
    (Aus „Besuch aus Weimar“ von Gert Heidenreich, Schriftsteller, *1944 in Eberswalde)