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Fuse markings. The inscription on the three-phase protection - B20.

dziura78 75362 19
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What does the B20 marking mean on a three-phase circuit breaker/protective device?

B20 means a 20A protective device with a B tripping characteristic: it can carry 20A for a long time, a small overload such as 25A may flow for a few minutes before it trips, and it will disconnect very quickly (in under 0.2 s) when the current rises to about 2.5–3.5 times 20A, roughly 50A [#2802644] It is a circuit breaker/automatic switch, not a one-time fuse, so it disconnects overload and short-circuit currents and can be switched on again after tripping [#2802958][#2804846]
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  • #1 2802528
    dziura78
    Level 11  
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    Hello, what does this inscription mean on the three-phase protection "B20"
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  • #2 2802530
    matidanko6
    Level 27  
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    ABCs are reaction rates and the numbers are the amperage it can withstand
  • #3 2802540
    dziura78
    Level 11  
    Posts: 7
    Rate: 7
    these 20A means that a current of 20A can flow through each phase and the protection ni will break?
  • #4 2802644
    mksm
    Level 18  
    Posts: 171
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    It means that 20A can flow for a long time, because, for example, 25A can flow a few minutes, then the fuse blows. while the letter B means that this fuse will blow in less than 0.2 seconds if a current of at least 2.5 to 3.5 times greater than 20 A, i.e. 50A, flows through it.
    greetings
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  • #5 2802657
    marian1981.02
    Unitra equipment specialist  
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    mksm wrote:
    behind it, the fuse blows
    Markings "A '," B "," C "probably only apply to automatic fuses of the" S "type and they do not burn out, they just turn off!
  • #6 2802958
    mksm
    Level 18  
    Posts: 171
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    Hello
    The ABC and D markings refer to the fuse's characteristics and for other types it has different fuse markings, probably g or somehow. And the fact that the power switch turns off and does not burn out is right, but this is not what someone asked here, wanting to be a kionkretnym, the s -ka is not a fuse but a circuit breaker.
  • #7 2803617
    marian1981.02
    Unitra equipment specialist  
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    mksm wrote:
    if you want to be a cairncrete, it is not a fuse but a circuit breaker.
    Well, what is it? I don't think it's a light switch at home! It protects the circuit?
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  • #8 2803844
    menek
    Level 19  
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    The fact that the S-ka protects the circuit does not mean that it is supposed to be a fuse by name. S-ka is a redundant switch. In the power industry, circuit breakers are used to break short circuits and somehow no one calls them fuses ...
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  • #9 2804227
    marian1981.02
    Unitra equipment specialist  
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    menek wrote:
    The fact that the S-ka protects the circuit does not mean that it is supposed to be a fuse by name.
    Buddy "MENEK" - "Fuse", as the name suggests, protects the circuit. If the "s-ka", as you wrote, protects the circuit, it is logical to think that it is a fuse and that someone does not call him that, it is his business!
  • #10 2804499
    kosmo.1
    Level 11  
    Posts: 11
    Rate: 3
    I use SUCH a three-phase system to turn off the fan in the cold store.
  • #11 2804534
    mksm
    Level 18  
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    Dude marian1981.02, each fuse is a protection, but not every protection is a fuse, otherwise a balcony railing or belts in the car also had to be fuses, and these are only security.
  • #12 2804577
    marian1981.02
    Unitra equipment specialist  
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    mksm wrote:
    Dude marian1981.02, each fuse is a protection, but not every protection is a fuse, otherwise a balcony railing or belts in the car also had to be fuses, and these are only security.
    Buddy "mksm" Do not write nonsense about some barriers because we are probably talking about electricity, don't give me any stupid comparisons here and do not make a fool of someone! the same functions, but they are more convenient!
  • #13 2804758
    menek
    Level 19  
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    A colleague "mksm" wrote very well - not all the devices they protect are fuses. It is commonly called this way fuse-links, and then the name changed to redundant circuit-breakers, but it does not mean that the name "fuse" is correct for popular components. If it were so, it would be a "differential" in a home installation and a MV low-oil circuit breaker, they would also have to be fuses.
    Even the author of the topic used the word "protection", not "fuse" ...
  • #14 2804787
    marian1981.02
    Unitra equipment specialist  
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    Menek-Then write me a definition of what in your opinion is a fuse and what is a circuit breaker?
  • #15 2804846
    mksm
    Level 18  
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    fuse - an element that serves only to interrupt excess and short-circuit currents.
    circuit breaker with redundant protection (eg S) - an element that enables switching on and off the circuit and automatically switches off excess and short-circuit currents.
  • #16 2804858
    marian1981.02
    Unitra equipment specialist  
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    And what is the conclusion? As I wrote earlier that the function is the same! Only that the machine is reusable (not one-time) and you can additionally use it as a switch.
  • #17 2804987
    menek
    Level 19  
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    I fully agree that the function is the same. As for the definition of a fuse: everything is clear with a fuse, but an automatic fuse is e.g. a polymer fuse (multifuse). All devices that disconnect short-circuit and overload currents that can be manually controlled are circuit breakers.
  • #18 2805006
    marian1981.02
    Unitra equipment specialist  
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    Everyone calls himself what he wants! Switch-because you can turn off, Fuse because it protects the circuit-and this is his main task.
  • #19 2876604
    niikii
    Level 12  
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    Well, gentlemen, you are dwelling on the definition, and this is not what the questioner meant. I admit that I am also curious about the markings on the fuses. And to make it easier, maybe let's separate the fuses from the S's.

    I greet all concerned.
  • #20 2878621
    lechm56
    VIP Meritorious for electroda.pl  
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    kosmo.1 wrote:
    I use SUCH a three-phase system to turn off the fan in the cold store.

    FR circuit breakers should be used.
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Topic summary

✨ The inscription "B20" on three-phase protection devices indicates that the device can handle a continuous current of 20A per phase. The "B" classification signifies that the fuse will trip in less than 0.2 seconds if the current exceeds 50A, which is 2.5 to 3.5 times the rated current. The discussion also differentiates between fuses and circuit breakers, noting that while both serve to protect circuits, circuit breakers (like the "S" type) can be reset and are not consumed like traditional fuses. The conversation highlights the importance of understanding these markings for proper electrical protection and safety.
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