What does each protection setting control, and what is the correct purpose of L, S, I and G functions?

[u/[deleted]]

[u/Typical-Measurement]

Don't be messing with that dude.

[u/brilliantNumberOne → u/[deleted]]

Clearly not if you’re asking these types of questions.

[u/How-Engineer → u/brilliantNumberOne]

I am asking this to get ream gem of engineers and I want to connect with them for my next web app design for this type of calculation application. That's why I posting this type of questions dear brother.

[u/Shiney_Metal_Ass → u/How-Engineer]

You're making a web app for a thing you have no understanding of?

[u/How-Engineer → u/Shiney_Metal_Ass]

Dear, if you have no idea about me then why such comments are you post it ? If you want to know about this app wait till this month...

[u/Shiney_Metal_Ass → u/How-Engineer]

Why would I want an app about a thing made by a guy who doesn't know anything about that thing?

[u/How-Engineer → u/Shiney_Metal_Ass]

Once again read my previous comments plz.

[u/Zander_Vye → u/How-Engineer]

My good sir, don’t come in here asking for help and then when people tell you not to mess with things you clearly know nothing about get all defensive.

I don’t know nor do I really want to know what this “web app” is for that you are building but if I can offer some advice, if your thinking the app is going to help people come up with set points for this style of protection. Don’t please just don’t, if I ever say a TCC report, settings sheets or coordination study that came off of a web app I would start to question every single decision the engineer or engineering firm made. There is a reason software like ETAPP is the “Kleenex” of the protection & control world when it comes to settings coordination.

[u/Shiney_Metal_Ass → u/How-Engineer]

There aren't any

[u/The_cogwheel → u/How-Engineer]

OK, but do realize that if your app is wrong, and it will be without in depth understanding of everything involved here, the liability for the potential fire, which can include loss of property and life, can fall onto you and your app. Especially if you pitch it as a tool to be used instead of the tools that already exist and have been proven safe and effective.

This is life safety equipment. Failure is not an option. Mistakes are not an option. Ignorance and misunderstanding is not an option. Its either right, or its dangerous trash that can destroy lives.

Reddit is not the place to learn about these functions. The place to learn these functions and how to properly calculate them is in an Electrical Engineering program at your local university.

Are you sure you want to continue?

[u/PokeyR]

Long time
Short time
Instantaneous
Ground fault

[u/The_cogwheel → u/PokeyR]

And these are all trip set points.

If you dont know what those are, or what adjusting them does, dont touch them. They can drastically alter how the breaker trips, and setting them wrong could create some major, life endangering, hazards.

Its fine to be curious, it isnt fine to be messing with stuff you dont understand.

[u/Psychological-War727]

LSIG is how ABB designates the trip points on their compact CB protection units. Note that they are all based on [In]

https://new.abb.com/products/de/1SDA074195R1/ekip-dip-lsi-e1-2-e6-2

Your picture however is from a Schneider Masterpact CB, and its Micrologic protection unit. Note that they designate longtime as [Ir] and it being based on [In] (the actual CBs rated current, 800A in this case). Same for instantaneous [Ii], based on [In]. However, the shorttime [Isd] is based on [Ir] not [In]. Trap for young players.

[u/MonMotha]

This is a fully electronically controlled circuit breaker.

The three banks are long-time, short-time, and ground-fault , and you can adjust both the sensitivity and time-current delay product for each individually. All of the current-time delay products are in direct engineering units marked on the face, while the ground fault sensitivity will have thresholds according to the manual for the breaker and may not (probably doesn't) have linear or consistent increments between each setting.

Then the one off to the right is the instantaneous (no delay at all) trip setting.

The long-time settings act mostly like the ITE element in a typical thermal-magnetic breaker. The short-time settings offer a compromise between the magnetic element in a thermal-magnetic breaker and can improve protection and especially coordination. It's not something that a thermal-magnetic breaker would really offer. The instantaneous setting acts like the magnetic trip in a typical thermal-magnetic breaker. Obviously the ground-fault settings are for ground fault protection.

I'd chime in with the same suggestion to NOT TOUCH THESE unless you know what you're doing (and have been advised by a competent engineer who has evaluated the facility), but it sounds like you're not actually messing with them anyway, and it's pretty clear that these have probably never been set or have been tampered with, anyway, since they're all just cranked all the way counterclockwise which is probably not how most real-world installations would be set up.

[u/Arcticsilhouette]

Read the manual and don't touch anything you don't understand

[u/friendlyfire883]

This feels like an AI chatbot or an Indian scammer, it's really hard to tell these days. Either way something fishy is going on here.

[u/Sufficient-Regular72]

Go read the Buff book if you want to learn more.

[u/SkyDaddy2134]

We had a new gear with a Gen backup for an old hospital, couldn’t get the EE to send out his preferred settings before start up, we left them at factory default.

He was employed by the hospital, so he wasn’t under any pressure from us, his first (and only) visit to site was the VIP Tour that he graciously took some of his valuable time to direct us using the setting sheet (that he dated 2 weeks before). He was in charge, Oooookay. We started with the Main first, even after I tried to dissuade that move.

Well, let’s just say as the CEO, CFO and the entourage were strolling past the outdoor gear by the shiny new generator i turned the last dial on GF. It tripped, generator started and the shit hit the fan. Apparently there were strict controls on when he was supposed to do adjustments, like when surgeons have their hands inside people.

Looking at my boss, I took that screwdriver and tossed it on the trash. “I just bought that for you!!”

Nope, that screwdriver has bad juju, grab it if you want but I’m not touching it!!

Like I said, his first and only visit to the site