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I have an inverter that I would like to start a generator. The inverter has a simple relay with no/c/nc contacts. To start the generator requires a wake up call, pause, and then a run signal on the run terminal.

If I connect the NO contact to the run terminal and set the inverter to start the generator it will wake up. After wake up I then need to break and remake contact to get the generator to start. Is there a way to do this with one component or will I need to use multiple time delay relays?

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    \$\begingroup\$ I suppose you could have a spring-loaded rotary solenoid that swipes a carbon brush across two parallel contacts with a gap between those contacts. Pretty specific though. \$\endgroup\$
    – DKNguyen
    Aug 24, 2022 at 5:26
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    \$\begingroup\$ Depending on your requirements, you could build all of this with a chain of timer relays. A bit cumbersome though. It would be much more compact (and affordable in volumes) to build a little custom PCB. \$\endgroup\$
    – Lundin
    Aug 24, 2022 at 6:31
  • \$\begingroup\$ You can get small PLCs (programmable logic controllers) which you can program to do what you want. \$\endgroup\$
    – Kartman
    Aug 24, 2022 at 9:19

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There's no type of relay (at least that I know of) that does this very specific task.

You're trying to solve an easy control problem with a complex electromechanical setup. Since this is error-prone, relatively expensive and complicated, we don't do that since the late 1970s, when microcontroller became ubiquitous.

So, use your existing standard relay, buy a < 1€ microcontroller, take a minimal example from the vendor, change it to toggle a pin after the times you need, and connect a transistor to switch your relay to said pin.

If you're hesitant about the complexity of a microcontroller design, buy the cheapest microcontroller eval board you can find: these come with all the electronics you need to supply power etc to your microcontroller, a programmer built in, and a wealth of examples. And although the microcontrollers on these boards are typically 32 bit powerhorses compared to what you need, they're < 15€ for the full board. In exchange, you got so plenty of resources you effectively don't have to worry about programming efficiently, and get interesting extra stuff like watchdog timers (which can be used to reset everything if something hangs), ADCs (which can be used e.g. to monitor motor currents) and enough pins to connect displays and user buttons.

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