I have a diy sprinkler controller (opensprinkler) that is networked and has some nice features. One of the reasons for it is I have a lot of zones and this is easily expandable.
My question is about protection from shorted valves. This controller is weak in this area and I have several zone outputs that are bad. From what I have read it is not uncommon for a valve to fail with a short or low resistance and some controllers will report it.
Are most commercial controllers have some sort of short circuit protection so the controller isn't damaged by shorted valves?
How does this protection work? It seems some use more sophisticated means that just a fuse that opens.
The system has a 2A fuse in the 24VAC input. This powers the raspberry pi circuit board and the zone outputs. I separated the pi power so the fuse just feeds the zone outputs. A typical zone is about 0.22A so the fuse seems like overkill. I think a 1A should be sufficient.
A 2.2 ohm resistor is in series with each output but it doesn't limit the current to a reasonable value and burns up for shorts making a mess of the circuit board. I think they eliminated the resistors on later versions.
My question is about protection from shorted valves. This controller is weak in this area and I have several zone outputs that are bad. From what I have read it is not uncommon for a valve to fail with a short or low resistance and some controllers will report it.
Are most commercial controllers have some sort of short circuit protection so the controller isn't damaged by shorted valves?
How does this protection work? It seems some use more sophisticated means that just a fuse that opens.
The system has a 2A fuse in the 24VAC input. This powers the raspberry pi circuit board and the zone outputs. I separated the pi power so the fuse just feeds the zone outputs. A typical zone is about 0.22A so the fuse seems like overkill. I think a 1A should be sufficient.
A 2.2 ohm resistor is in series with each output but it doesn't limit the current to a reasonable value and burns up for shorts making a mess of the circuit board. I think they eliminated the resistors on later versions.