I have following electric schema which works on 230V AC.
I am using remote controlled relay(RCR) to start and stop the engine. The problem is that I am not sure about wireless signal quality and I afraid that it may end in the situation that engine has started but not stopped.
Because of that I have safety switch which is time relay(TR). Circut works like this:
- TR has NC connectors which are giving current to RCR even when it's turned OFF.
- When RCR receives swiich signal it gives controlling signal to TR and powers the engine.
- Engine is running and TR is counting time to change NC connector to open.
- When TR reaches the time it switches NC connector to open.
- When NC connector is open three things happens:
- engine stops working
- RCR is turned OFF
- TR is turned OFF
And here it is a problem. When TR is turned off NC connector returns to the state closed. Because of that RCR is back online. But the time it happens is so short that it's not able to return to it's default state which is ON, so the system is back in point 2 instead of 1.
My question is how can I extend the time of TR open state? Naturally it will mean that I need some sort of "UPS" on TR controlling line, but I need something cheap that will last for 1-2 seconds(maybe even less). Should I use some sort of capacitor?
I am kind of new in this field and some terminology may not be correct or some asumptions may be wrong.
I found some relay which holds a state without power for some time. I have no idea how it is called but it works like this:
When it receives signal it changes connector states and when the signal is gone it holds the state for given time. I've changed my circuit a bit to work with this and it looks like this now:
And works like this:
- TR is giving power to RCR
- When RCR is switched on it gives power to engine and hold state relay( HSR)
- HSR is controlling TR control signal.
- When HSR receives signal it switches TR counter
- When countdown is finished RCR is turned off.
- HSR is no longer recieving signal, but it still holds state for desired time.
- RCR returns to default state.
- HSR countdown finishes and it returns to default state.
- Whole circuit is in starting state.
This solution is much cheaper than adding additional 4 relays.
I have an another idea, but I am not sure if it will work. My time relay is 12÷264 V AC/DC. I am considering using AC/DC 230/12V transformer and some capacitors for holding state. I have two capacitors 470uF 200V but I am not sure if they are big enough. Using transformer and capacitors would not require additional delayed timer.