Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [circuit-breaker]

An automatically operated electrical switch designed to protect an electrical circuit.

146 questions
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What causes a fuse to blow, the current or the power?

Fuses and circuit breakers are often specified at a certain current they will 'blow'. Increasing the current will also increase the power. So if a fuse is rated for 12V DC and 20 A, this would be equal to 240 watts. If a different voltage is…
Jackson Harvey
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Do circuit breakers trip on Apparent or True Power?

The thermal and magnetic protection for AC circuit breakers take into account both the timing and the magnitude of the AC current passing through. Does a standard circuit breaker trip on the current related to the Apparent (kVA) Power, or the…
Brethlosze
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How do I protect myself when testing a PCB that involves an AC line?

I have to test prototype PCBs that convert household AC into several DC voltage levels. I concern about my safety when working with AC and would like to know how to properly setup a testbench that, for example, will trip a circuit breaker or break a…
Natthapol Vanasrivilai
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Why can an AC circuit breaker not be used in DC circuits?

Let's assume that I want to use a 20-amp GE AC circuit breaker in a DC circuit. So, after testing it in a DC circuit with some loads and ammeter + clamp DC amp meter I find the current at which the breaker trips. Let's assume as an example this is…
The_Vintage_Collector
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Could an uninterruptible power supply for energy intensive appliances balance the power draw and help my breaker stop tripping?

Non-engineer here. Well, not the electrical kind. About once a week the breaker to my office (read: gamer cave) trips. I just noticed that our 70 inch TV, 2 x Echo Studios, etc. in the living room on the other side of the wall also go out. There's…
J.Todd
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Why does a circuit breaker voltage rating differ between AC and DC?

I'm looking at circuit breakers from Allen Bradley's 1492 series: (https://configurator.rockwellautomation.com/api/Doc/1492-SPM%20Specifications.pdf) For each circuit breaker, it lists a AC and DC voltage rating. Why would the voltage rating differ…
Izzo
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Why cut both live and neutral wires?

It is a common practice, for high power loads such as boilers, furnaces, etc., to install a circuit breaker that "cuts" both live and neutral wires - at least in Europe. In my search for EVSE, I saw the following figure, in which AC and DC circuit…
thece
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DC Parallel Breakers

I need a single-pole circuit breaker for a 200A, 48V DC battery bank powering a solar inverter. The batteries are LiFePO4 and capable of large short-circuit currents on the order of 10 to 15 kA. Large molded-case (MCCB) breakers are available with…
Eric
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Help identify this breaker

I salvaged this breaker unit from the scrape yard. Compared to every other breakers i have seen before, this is very different. It has 5 terminals. The labels are very clear but there is no information about the usage of its terminals. The…
soosai steven
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What is meant by the term "galvanic contact" in this sentence?

Simply speaking, a switch or circuit breaker are two metallic contacts (electrodes) that are in GALVANIC CONTACT with each other when closed and separated by a certain distance when open. I don’t really get what galvanic means in this contest. I…
Tommaso Bendinelli
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Does a circuit breaker trip depending on voltage or current?

I've have a GE 120V 20A circuit breaker. I'm aware that once it exceeds the 20A rating the breaker does its job and trips, but what happens if the current is less than 20A and the voltage lets says jumps to 320V. Will the breaker trip?
The_Vintage_Collector
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Are there breakers which can be triggered by an external signal and have to be reset by hand?

Essentially, I would like to connect a breaker to a smoke detector and have it trigger when it activates. Are there any breakers that can be triggered by a separate external signal and which have to be manually reset by hand?
Reewen
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Caravan park with 3 phase power supply, our B phase amps are overloading and tripping the circuit breaker

We have had the phases balanced, and the problem is still occurring. We initially added a 60 kVA generator taking out our amenities block, and this helped during peak power times of day. It is no longer solving the problem, and the B phase is again…
Alva Beach Tourist Park
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Avoiding breaker trips with a heater and PWM signal

I am controlling a 1500W heater with an SSR at 5Hz. The heater's voltage is 110V freq is 60Hz and my breaker is rated for 15A. I have other loads on this circuit consuming about 2A. This means the maximum current draw is (1500/110) + 2A =…
Feynman137
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Why do Americans use fuses and not differentials and breakers like Europeans do?

I recently moved to North America, and I was wondering why the houses here seem to be protected by fuses rather than breakers and differential switches like we have in France for example. It would seem to me like in most cases it would be difficult…
Mister Mystère
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