[skinwill]

I worked at a television station years back that was designed in such a way that the lights going up the tower were powered by the separate phases of three phase AC with the one at the top powered from all three combined. This was pretty normal but what the engineer had done was rotate them at every level so that if a phase was dropped you could count the lights and quickly see from a distance that the power wasn't right. 4 lights was good, 3 meant you dropped a phase, and so on. I thought it was a pretty clever way of keeping light on all sides of the tower while being able to tell from a distance that a phase was out.

[xenadu02]

This is best practice for anyone who uses three phase power.

A machine shop should connect 1/3 of their lights to each phase so it is immediately obvious if a phase gets dropped. Lots of equipment will suffer on two of three phases but with lower performance or even damage.

[quickthrowman]

> This is best practice for anyone who uses three phase power.

No, it’s not. It’s a neat trick that visually reveals when the utility drops a phase, but there are better ways to handle avoiding equipment damage.

Best practice is to use phase monitoring relays that can de-energize a motor when a phase is dropped/reversed to prevent damage. The trip time is adjustable and it’s more reliable than manually hitting an e-stop. It also won’t let a motor with incorrect phasing start up either. You see phase loss relays on a lot of compressor motors and other large motors.

Here’s a flyer for an Eaton product: https://www.eaton.com/content/dam/eaton/products/industrialc...

[genter]

I was told that you want lights on all 3 phases so that you can see spinning things spin. If the lights are on single phase, they will dim 120 times a second, and the strobe effect can cause spinning things to appear stationary. With 3 phase, at least 1/3 of the lights are lit all the time.

[MisterTea]

At work we run a lot of machinery with motors and its obvious when phase loss happens. From my office I can tell if the lights go out/dim and the usual shop "hum" becomes a buzzing grunt that is immediately identifiable. Older machines have to be manually powered down but the machines I rebuilt have phase loss protection in the PLC thanks to a power monitoring terminal in the IO (Beckhoff EL3453.) Since the PLC is on 24V DC I have a capacitor backup module fronted by a 24V PSU that takes the 480V three phase power which tolerates a phase loss. The machine safely stops the process and shuts down the pumps and any other AC loads, then waits to be manually powered off as the PSU and DC side doesn't care.

[geerlingguy]

Clever! I know I talked to the folks at Masterclock in St. Louis recently about one of their clock displays; they intentionally default the separators to flash if the clock is not synced to NTP, and then they go solid once the connection is established.

It's a quick way to know if something is down, using context clues that are already there to begin with!

[skinwill]

Jeff, it's very cool to hear from you as I have enjoyed your videos for some time. I would like to make one request though. Next time you do a project like "How I almost broke MrBeast's Ages 1-100 video" that involves setting up interactive electronics for an event, you should really call me. I managed interactive technology deployments for the automotive marketing industry for over a decade. It's a niche that has unique challenges which you fell face first into. I would be happy to help make things go much smoother should you ever do something similar. Proof: https://imgur.com/a/5z5JrwT I'm also on Reddit, same screen name if you want to dm me there.

[butlike]

Fascinating

[dotancohen]

Phascinating

I couldn't help myself, downvote at will.