ElecTech Posted May 5, 2016 Posted May 5, 2016 I am attempting to indicate a roller shutter has been left open with an LED indicator located at a drivers desk (point A)... the roller shutter is at point B with a lever that when bolted across a relay operates to N.O. Distance from point A to point B is 200m. What's my best way of doing it i.e. voltages and size of cables.... I was thinking of sending a +24VAC down one core from a panel that were having made, running through the relay to connect directly back to the LED indicator. and have 0v connected straight from panel to indicator.... Quote
ElecTech Posted May 5, 2016 Author Posted May 5, 2016 Shutter is on a internal section going into a segregated part of the building so no use in this instant. Door is not alarmed. Quote
sixwheeledbeast Posted May 5, 2016 Posted May 5, 2016 Would need to be DC for LED unless you want it to flash at 50Hz? What kind of LED, how much current? Then you can work out volt drop. Quote
Nova-Security Posted May 5, 2016 Posted May 5, 2016 Hes using a relay to switch it, so the power must be local to the LED so volt drop doesnt matter. 12vdc 1k resistor Quote www.nova-security.co.uk www.nsiapproved.co.uk No PMs please unless i know you or you are using this board with your proper name.
ElecTech Posted May 5, 2016 Author Posted May 5, 2016 1 minute ago, Nova-Security said: Hes using a relay to switch it, so the power must be local to the LED so volt drop doesnt matter. 12vdc 1k resistor Volt drop will matter as I'll be running the power through the relay 200m away? Power will run from the "panel" through the relay 200m away then back to the LED which is located on the panel... so round trip of 400m... I'm just wondering if there's a better solution. 23 minutes ago, sixwheeledbeast said: Would need to be DC for LED unless you want it to flash at 50Hz? What kind of LED, how much current? Then you can work out volt drop. Current is 20mA.. LED is the type is fitted on industrial switch panels?? if that makes sense. Quote
sixwheeledbeast Posted May 5, 2016 Posted May 5, 2016 48 minutes ago, Nova-Security said: Hes using a relay to switch it, so the power must be local to the LED so volt drop doesnt matter. 12vdc 1k resistor It doesn't matter where the relay is there will still be current through the switch to trigger the relay. 38 minutes ago, ElecTech said: Volt drop will matter as I'll be running the power through the relay 200m away? Power will run from the "panel" through the relay 200m away then back to the LED which is located on the panel... so round trip of 400m... I'm just wondering if there's a better solution. Current is 20mA.. LED is the type is fitted on industrial switch panels?? if that makes sense. Yes, so they will have there CLR built in so need a 24Vdc or 12Vdc supply to your panel mount. You need to calculate the resistance of the cable you are using and use V = I/R I imagine 1mm 2C flex would be fine with such a small load on 24Vdc. Quote
sixwheeledbeast Posted May 5, 2016 Posted May 5, 2016 Run +ve from the supply to a panel mount QB fuse in the panel, out through the relay and back to the LED. -ve straight to the LED Quote
Nova-Security Posted May 5, 2016 Posted May 5, 2016 1 hour ago, ElecTech said: Volt drop will matter as I'll be running the power through the relay 200m away? Power will run from the "panel" through the relay 200m away then back to the LED which is located on the panel... so round trip of 400m... I'm just wondering if there's a better solution. Current is 20mA.. LED is the type is fitted on industrial switch panels?? if that makes sense. Why run the poer to the relay at the contact and back? Run the contact wires to the panel RB007 trasistorized relay then its only doing 200m Quote www.nova-security.co.uk www.nsiapproved.co.uk No PMs please unless i know you or you are using this board with your proper name.
sixwheeledbeast Posted May 5, 2016 Posted May 5, 2016 Eh? I think we have both read this differently. I see this as A (the LED) and B (the relay output). I assume there is no power at B, A would be easiest place to locate PSU as it can go in the cab. One run of 200m 2C 1mm should do the job? Quote
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