Help in creating fuse protection for each zone & line monitoring

[John K]

I would like to create an efficient means of fuse protecting each zone on the controller as well as having some means of line monitoring. By this I mean an indicator light showing when A) Controller to solenoid connection is good (wire is not cut). B) Solenoid is functioning fine, ie fuse is not blown. C) There is power to the system.

I have a number of controllers, each running with the potential of maxing out their zone capacity (72 zones). I want to create the necessary circuitry in as little space as possible so that all things can fit in my controller boxes.

In my experience, when solenoids go bad they can fry the zone on the controller, making that zone inoperable. I can place an inline 1A fast blow fuse right after the controller, before the solenoid, and that seems to protect the controller from the bad solenoid. This would be one fuse per zone. Is it possible to somehow share the fuse instead of needing a fuse per zone?

I have seen these circuit boards: http://www.electronics-salon.com/index.php?route=product/product&path=4946_7565&product_id=54667
which should give a quick way to add many 5x20mm fuses in a smaller area. I like this but still doesn’t solve the other goals.

This board: http://www.electronics-salon.com/index.php?route=product/product&path=4946_7565&product_id=54661 would give an indicator LED that turns red when the fuse is blown. Looks as though when the fuse blows the 24V overcomes the resistor and powers ups the LED. Problem here, I believe, is that the LED will not be on unless the specific zone with the blown fuse is currently running. Also, this board says working voltage 5-48V DC, my systems are 24V AC, would this not work because its intended for DC?

Ideally, I want to be able to look at the system and see if there are any issues with any of the zones, even if they are not in use. From this point I thought perhaps a relay switch that connects a bi-color LED circuit that has its own power supply so that the LED is green when things are good, and red when the fuse is blown. This is where electronic circuitry gets beyond my knowledge.

An LED such as this: https://www.amazon.com/EDGELEC-200pcs-Emitting-Assorted-Resistors/dp/B0785G4GH2/ref=sr_1_12_sspa?keywords=led%2Bdiodes&qid=1564729508&s=gateway&sr=8-12-spons&th=1

A Relay such as this: https://www.amazon.com/uxcell-10Pcs-Power-Electromagnetic-Mounted/dp/B0756Y4YX3/ref=sr_1_18?keywords=spdt+relay&qid=1564801536&s=gateway&sr=8-18

Perhaps when things are good, a relay that is normally closed would power the green leg of the LED and when the relay opens it powers the red leg of the LED. The LEDs would all share a power source specific for them so that the zone doesn’t have to be on in order for the LED to be on. I am not sure how this works because the relay would need to be powered by the 24v AC of the specific controller zone, which doesn’t always have power, in order to change state…

I would love to be able to simplify this down, so instead of 72 relays, its just one, but I don’t know if I can interconnect the various zones safely, again this is beyond my knowledge but could learn if led the right way. It may be better to have one audible siren sound when something is wrong but I still see this leading to needing interconnecting zones. But in this way I don’t necessarily need the green LED so much as just knowing something is wrong, and then seeing an LED light on the particular zone fuse that is blown.

Very much would like any input that you guys can offer. Any confirmations of what I’m thinking and of ways to make it more simple is much appreciated.

[John K]

Thank you for taking the time to respond! It’s great to see these pictures, very helpful.

I have looked at the Din Rail components, probably ideal for this and will have to look into further.

If I’m understanding your set up correctly, you have 8 zones currently but 16 relays (black, middle left)? I faintly see wires on the upper portion of the Schneider relays connecting them all together? Are they sharing a common wire completing the obit valves circuits back to the power supply? Also, is that a pc power supply up top for the the orbit valves (24v AC) or the relays and controller (12v DC)? What model relay is in the socket?

The grey Din Rail connectors in the middle, I don’t follow their intent, can you elaborate on those? You’ve done a nice job hiding wires so I can’t follow the circuit. I believe the tan Din Rail connectors on the far right are the fuses for each zone?

Thank you again for your time!

[John K]

Just realizing you added more details to your post, thanks this helps.

Do the LED indicators for each zone stay on even when the zone is off? As I understand things they would not?

I know that this situation is possible:

Each zone has an inline fuse protecting it from the valve. Before the fuse, a LED indicator is wired so that it only comes on when the fuse blows (a resistor in series to LED that is parallel to the fuse I believe).

I am wondering if this situation is possible:

Instead of individual LEDs, would it be possible to have all zones connected to a shared relay, before their fuse, that would only ever be turned on if one of the fuses blows on a zone? It would only need to trigger another circuit to power on and then it could turn off (when the zone turns off per its schedule). Would this be a shared relay that gets powered on only when a fuse is blown? It would change the state of another circuit which would need to stay powered on even after the relay turns off again. Some reset “button” would be needed I suppose. This way I can have a large visible indicator light outside the box or an alarm that stays on.

Anyone else have experience adding on circuit protection and alerting to our controllers?

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