Amp Interruption Calculation_Tech_Lib_Electrical_Formulas.pdf
446 KB
Dont know who might need this, but here's the formula for calculating the amp interruption rating needed for a main breaker from your utility service. I wrote this spread sheet a few years ago. Originally my solar system had a shutoff that killed the backfeed from the solar inverters. But since I've reorganized my system, that switch has been bypassed. Next week I'll be routing my service entrance cabling from the meter base thru a 100amp lockable shut off switch. It is required by code to have a lockable shut off when backfeeding the grid. Since I can't separate my solar, I'll just separate the whole house.
Basically, at 25kva transformer can deliver 100amps @ 240vac but in the case of an arc fault, it could deliver 8000amps of surge. If you have a longer feeder like I do (275ft), resistance of the wires to the pole will limit that current. So my limit is 2916amps. This is well within the limits of the fused knife switch and the 1 AWG cable I'll be using.
Basically, at 25kva transformer can deliver 100amps @ 240vac but in the case of an arc fault, it could deliver 8000amps of surge. If you have a longer feeder like I do (275ft), resistance of the wires to the pole will limit that current. So my limit is 2916amps. This is well within the limits of the fused knife switch and the 1 AWG cable I'll be using.
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Most of us have heard of fast fuses and slow blow fuses. But did you know breakers can also be fast and slow rated?
Here's the rating curve designations for circuit breakers. All of them will handle 100% of their rated current forever, but D type will handle 20x its rating for 1/2 a second. Z rated breakers will always trip instantly at 2x their rated current. So D is slow blow and Z is fast.... and all ratings between.
Now you know.
Here's the rating curve designations for circuit breakers. All of them will handle 100% of their rated current forever, but D type will handle 20x its rating for 1/2 a second. Z rated breakers will always trip instantly at 2x their rated current. So D is slow blow and Z is fast.... and all ratings between.
Now you know.
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The majority of breakers trip for thermal and magnetic reasons. Thermal happens when you are just barely over the current rating and eventually the breaker trips. Magnetic is when there's a short circuit and a strong magnetic field is generated tripping a cam inside. Additionally there are GFCI breakers that measure the amps in/out of the hot and neutral wires. If the amps aren't exactly the same that means that there is someone getting shocked or something has shorted to ground. if there's an imbalance of 5ma they will trip. So if you have 20 amps going out on the hot and 19.095amps returning on the neutral, the breaker will trip.
https://www.youtube.com/watch?v=VGj32euYZ2c
https://www.youtube.com/watch?v=VGj32euYZ2c
YouTube
Circuit Breaker Basics - How do they work?
In this video, we'll discuss the basics of circuit breakers. We'll cover the types of circuit breakers and their uses, as well as the different types of circuit protection. After watching this video, you'll be able to understand and use circuit breakers effectively…
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Forwarded from Before Our Time
Off grid air motors. They use a gas engine and/or windmill to make compressed air. They run sewing machines, drill presses and ceiling fans from compressed air.
Join us now: Before Our Time📜
Join us now: Before Our Time📜
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Forwarded from Working Men Memes (Hammer)
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Forwarded from Sharky’s Basedposting Channel - TG Microceleb (SHARKY)
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One of the nearby farmers reached out to me to ask about solar. This is as easy as it gets... He sent me his power bill and we can see he needs 2200kwh in june and 1260kwh in february. All we need to do is plug in some numbers into the PVWatts website https://pvwatts.nrel.gov/pvwatts.php and play with the tilt and number of panels until we cover those two months. Just play with the tilt from 15degrees to about 45 degrees in 5 degree increments. When you nail it down, add 20% power production to the system and off ya go.
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So we just came out of three or four cloudy days in a row. I had to buy back some of the excess power I've previously sold to the power company. 14kwh one day and 31kwh the next. This brings my total to 71.9kwh that I've had to buy back because I don't have quite enough battery. an additional 14kwh battery would have covered everything except yesterday, where I would have needed two more.
If the grid was down in the future, I would have had to run the generator this year a total of 14hours. She burns a quart an hour, so that's somewhere between 3-1/2 and 5 gallons of diesel this year.
Pretty damn good.
If the grid was down in the future, I would have had to run the generator this year a total of 14hours. She burns a quart an hour, so that's somewhere between 3-1/2 and 5 gallons of diesel this year.
Pretty damn good.
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I'm on the fence about sharing this one... on the one hand this guy has built a monster system and he did everything over the top. On the other hand, it's so over the top that the price might scare you and I want ya'll to know solar doesn't have to be expensive. This is a hell of a project.
https://www.youtube.com/watch?v=lO7KdMe6kYM
https://www.youtube.com/watch?v=lO7KdMe6kYM
YouTube
24kW PV Array
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Geez I hate unserviceable items. Dishwasher is leaking. Last week I replaced the door seal because it dry rotted. One week later, there's a new puddle on the floor. The pump housing seal is leaking. I can buy the top part of the casing for $58, but the seal is attached to the bottom part and the pump, bottom and seal is $290... and the seal is not available separately. That seal is literally dissolving.
This frustrates me because even if I fix this seal with caulk, how long before the next one fails?
This frustrates me because even if I fix this seal with caulk, how long before the next one fails?
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https://youtu.be/KCKua0hrCrM
This makes a 33lb 15kg block that sets up in a few minutes and fully cured is 2 weeks. 37kg of gypsum, 2kg of cement , 5 liters water and the balance of foam makes three 15kg blocks.
This makes a 33lb 15kg block that sets up in a few minutes and fully cured is 2 weeks. 37kg of gypsum, 2kg of cement , 5 liters water and the balance of foam makes three 15kg blocks.
YouTube
Amazing Process of Making Foam Concrete Blocks | Production of Foam Blocks 2024
Step into the fascinating world of foam concrete block production in this mesmerizing video! Witness the incredible process of transforming a mixture of cement, water, and foam into lightweight and durable blocks that are revolutionizing the construction…
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Forwarded from Jason
UHI Electric Mini Excavator Review Good for a Small Farm?
https://www.youtube.com/watch?v=cW0w2LSraic
https://www.youtube.com/watch?v=cW0w2LSraic
YouTube
UHI Electric Mini Excavator Review Good for a Small Farm?
The UHI Electric Mini Excavator. Is it a good choice for a small farm? This week I put the little UHI E12 through it's paces, find it's limits and explore the future of electric plant.
UHI E12 https://www.unitedheavyindustries.com.au/product/e12/
Unedited…
UHI E12 https://www.unitedheavyindustries.com.au/product/e12/
Unedited…
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