Tinkerer 👍🏾nice example. We apply a belt and braces approach in USA upstream and downstream, location of fault will matter as well and obviously RCD trip current and trip time curves. Interesting in my own property with AFDs upstream and downstream both operate simultaneously no matter where the simulated fault occurs. The solution to selectivity in my mind is selectivity that imply larger boards, shift from rings to radials, with dedicated circuits for specific large equipment and separate circuits for each room. When trips occur they simply isolate in very specific circuit and room, ensuring system operation in the rest of the home.
Great video Mark, the memories of college days. I also find it interesting by doing a ramp test on the rcd to see how sensitive it is by trip time, some I find are surprisingly low from the stated 30mA average is about 26mA.
Thanks mate, very kind. I enjoy these board based videos more than the site ones. The views dont agree lol. Yeah RCD ramp testing is a brilliant idea! On the list now.
@@electrician247 You do narrow the audience with specific videos like this but it's good to see different content and real world scenarios.👍 I think people prefer to be nosey and see how others do things 😂. But content is content and will likely grow in views later on. I'm struggling for time at the moment that said should have a video dropping tomorrow morning hopefully.
Discrimination/selectivity for fuses is a fairly complex subject from what I remember of my college days it is to do with the energy let through I^2t (A^2s) of the downstream device not exceeding the pre arc energy (A^2s) of the upstream device. Some manufacturers have charts in their technical notes about this, I think I have seen charts in an old merlin gerin book regarding discrimination of their mccbs
Smallest fuse possible furthest die stream, times that fuse rating by 1.6 and that number closest to a fuse is the next fuse. You’ve achieved selectivity quite easily using this method
@Webbster77 it's funny referencing my experiments. In terms of what you are supposed to do. For full selectivity it's very difficult and careful reviewing of curves and let through energy are the only way. Even then it's not bullet proof. So we generally end up in a place with partial selectivity. Which is no bad thing you just on occasion get operation of up and down stream devices.
Tinkerer 👍🏾nice example. We apply a belt and braces approach in USA upstream and downstream, location of fault will matter as well and obviously RCD trip current and trip time curves.
Interesting in my own property with AFDs upstream and downstream both operate simultaneously no matter where the simulated fault occurs.
The solution to selectivity in my mind is selectivity that imply larger boards, shift from rings to radials, with dedicated circuits for specific large equipment and separate circuits for each room. When trips occur they simply isolate in very specific circuit and room, ensuring system operation in the rest of the home.
Great experiment.
Great demo Mark
Great video Mark, the memories of college days. I also find it interesting by doing a ramp test on the rcd to see how sensitive it is by trip time, some I find are surprisingly low from the stated 30mA average is about 26mA.
Thanks mate, very kind. I enjoy these board based videos more than the site ones. The views dont agree lol.
Yeah RCD ramp testing is a brilliant idea! On the list now.
@@electrician247 You do narrow the audience with specific videos like this but it's good to see different content and real world scenarios.👍 I think people prefer to be nosey and see how others do things 😂. But content is content and will likely grow in views later on. I'm struggling for time at the moment that said should have a video dropping tomorrow morning hopefully.
@@essexcountyelectricalltd look forward to watching! I just do it for fun really.
Discrimination/selectivity for fuses is a fairly complex subject from what I remember of my college days it is to do with the energy let through I^2t (A^2s) of the downstream device not exceeding the pre arc energy (A^2s) of the upstream device. Some manufacturers have charts in their technical notes about this, I think I have seen charts in an old merlin gerin book regarding discrimination of their mccbs
This is bang on and I have just the experiment in mind!
I knew the fuse would hold !
First times the charm lol
Gave up using Amtech ( now Trimble) software for this very reason , selectivity was a nightmare to achieve.
Smallest fuse possible furthest die stream, times that fuse rating by 1.6 and that number closest to a fuse is the next fuse. You’ve achieved selectivity quite easily using this method
Doesn't work in all cases. ElectricalOM and the scientific experiments in this and other videos prove it lol
@@electrician247why is this funny? How would you do it then? It’s basic understanding of how fuses work what else you supposed to do??
@Webbster77 it's funny referencing my experiments. In terms of what you are supposed to do. For full selectivity it's very difficult and careful reviewing of curves and let through energy are the only way. Even then it's not bullet proof. So we generally end up in a place with partial selectivity. Which is no bad thing you just on occasion get operation of up and down stream devices.