Questions tagged [fuses]

Questions regarding physical fuses. Fuses are a safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level. PPTC, PTC, and Polyfuse questions should use the Polyfuse Tag. Please keep in mind that repair questions are typically closed if not within the scope of the Site and FAQ.

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39 views

I am after a better specification of fuse than is on the board of a daikin split air conditioner

I picked up a couple of scrap daikin split Ftxs60bvmb The fuse on the control board is dead but it only says 3.15a 250v Is this a ceramic slow blow/ anti surge or a fast blow fuse?
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76 views

could this be a fuse?

I was so stupid to leave a Ring rsc 516 smart charger in the rain. Hopefully, only the fuse is blown. However, I am not sure where the fuse is? could it be the black thing on the photo? I did a ...
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1answer
116 views

Fuse detection in a lithium Battery Parallel connection

I really need your help in order to figure out a solution to detect a blow fuse in a 16S parallel connection. The issue is: Despite a fuse has been blow the voltage at the other side of the fuse is ...
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3answers
596 views

Why does AC input have a parallel resistor and capacitor?

Well, I am trying figure out a situation with images and a circuit diagram. I am checking all part looks normal, but if I insert this board on a machine the resistor is exploding and one leg of ...
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2answers
79 views

Why the redundant Fuse and redundant rectifier diode(Series)

I would appreciate if someone would share his thoughts on why would someone put a fusible resistor in series before an NTC ? . Also in the rectifier diode stage there are two extra series diodes in ...
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Basic Question: Why does this Short cause Blown Fuse?

I recently re-did some wiring connections for the horns in my car and accidentally shorted the wires out at the green wire in the picture below. This causes the 20 Amp fuse to blow, but I do not ...
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60 views

Fault protection circuit

I've searched the electronics stackexchange site but couldn't find an answer for the following 2 questions: For a home project I'm designing a circuit that is powered by a 24V battery. This battery ...
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1answer
58 views

What is the danger of going beyond the current limits of a wire carrying AC current

If I am using 18 AWG wires with a current limit of 16 A, what are the potential hazards of going beyond 120V,AC and 16A,AC(rms)?
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5answers
165 views

Why should a fuse be installed in live instead of neutral?

I understand why it should be installed in positive instead of negative side in DC, but this is AC. Direction of current reverses half of the time. It is said that installing a fuse in neutral causes ...
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Low resistance fuse selection for BMS voltage tap

I want to put inline fuses on the voltage taps of a battery bank I'm assembling. The BMS (Orion Jr) documentation requires a fuse with current rating of no more than 3A for the voltage taps, and ...
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54 views

120 VAC switch safety feature?

I am making a switch to control a desk light using this pilot relay. My module is plugged into a half-hot wall outlet that's controlled by a wall switch. The module uses a momentary-on switch to ...
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0answers
48 views

Thermal cutoff for a high current mains application

I'm designing an inrush current limiter for a large rack which will under normal conditions draw ~25 A at 230 VAC. I'd like to be able to trip the current carrying live wire if the temperature in my ...
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2answers
104 views

Varistor - Place before or after the fuse? [duplicate]

What is safer? Before or after the fuse? In my case the varistor is 10mm, 275Vrms, and it is currently placed after a 250Vac, 7A, 20mm glass fuse. Would the varistor blow the fuse easily if placed ...
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84 views

How to open this switch/fuse box

This is a power switch from a vacuum cleaner, specified as 8A / 250~, which I suspect contains a fuse that has blown. The plastic case has four "tongues" on the sides, but I can't figure out how to ...
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4answers
153 views

What *fuses* an electric fuse?

I build a quite lot of projects to learn electrical engineering, and since I was first introduced to what's called a fuse around 2 years ago and I always put one in my high voltage 220V mains for ...
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66 views

Where to fuse high voltage batteries connected in series?

I have modules of cells in series each with 48V. I wonder where is the right place to fuse the modules in series. (The current to trip the fuse is the same on every point). Version 1: simulate ...
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35 views

Fuse design for taking in account real-world very small transients

A bit of context I came up with this question after someone suggested that two fuses are better than a main one in the below configuration. The converters are SMPSs which regulate output voltage. ...
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1answer
2k views

What is the difference between F5AL250V and F5L250V fuses?

In the glass fuses' code F is for fast blown the second number is the current, but I ignore what is the difference between L an AL (if there is any). Could someone explain this.
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69 views

Fuses in Series for High Voltage Where Maximum Current is Low

I'll start off by saying that I know this not a recommend practice. I'm looking to build a regulated power supply that can supply 1200VDC at 300mA. The supply consists of a transformer, xenon tube ...
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229 views

Why use an inductor as a fuse?

I opened a small "wall-wart" power supply that had failed, and discovered the culprit to be a low-value (100µH) standard (axial, green) inductor. This inductor had a visible crack along it, as if it ...
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1answer
57 views

800 A 12 V bank Winston LiPo4 fuse size?

Installing this bank, with about 1 meter to my inverter/charger, but I want to add a fuse on the positive side. The inverter is a Victron 3kW. The charger is 120 A. The cables that I have now are ...
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1answer
51 views

Troubleshooting Power Supply Fault

I was using my 12 V Power Supply, and suddenly a spark occured near the AC input terminals. The power supply stopped functioning. I opened up the casing and found some blackish colour near the 250V 3A ...
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1answer
113 views

Would the diode and the fuse protect the other components if power wiring is reversed?

Would the diode and the fuse protect the other components if power wiring is reversed? Is the polarity of the diode correct?
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89 views

Can I replace a 6.3A fuse with an 8A fuse [closed]

I'm shopping for a Universal Travel Adapter and I've found this one which seems to meet all my requirements. I've used a nice one for years and it recently blew out and it doesn't have a replaceable ...
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1answer
67 views

Popped a power supply fuse - What did I do wrong?

I recently purchased a 5V 40A power supply that looks similar to this: It didn't come with a power cable, so I found one that I wasn't using and stripped the side opposite the three-pronged side (the ...
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1answer
63 views

Zener diode in parallel with both the input terminals and the output terminals

"There is a zener diode in parallel with both the input terminals and the output terminals. Combined with the fuse these should help in reverse polarity situations (it should blow the fuse before ...
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1answer
186 views

Why did my Atmega328p chips stop working?

I am fairly new to embedded programming. I bought some Atmega328P U chips (not Atmega328P-PU). I have two Arduino boards and the chips worked just fine, and were letting me upload sketches. One of ...
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3answers
315 views

Can I replace a 12a fuse with a 15a fuse on a 12v - 120v automobile inverter?

I'm hard wiring an inverter into my automobile. Tapping into a 15a fuse in the fuse box. To hard wire it I had to remove the "cigarette plug" and in so doing removed a 12a fuse. I have an inline fuse ...
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103 views

PTC or One time Fuse or fusible resistor for li-ion protection.any suggestion?

I designing a kind of portable device ,it contains 450mAh Li_ion or Li_Poly Battery (depends on space on PCB). I design this system for mass production (10k-20K). I want to add overcurrent protection ...
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2answers
4k views

What type of glass fuse is this and what does the spring do?

This is a standard sized glass fuse like what cars used before the 80s. I can faintly make out 20A, but I’m not sure what to call it in order to find a replacement. The fuse in the picture has not ...
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1answer
52 views

Poly fusing external peripheral device

The design I am working on is having peripheral connector with +5V power in it providing the voltage to the would-be connected device. There's relatively a long way inside the design from the ATX ...
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1answer
57 views

Pin protection fuses

A colleague of mine created the following circuit with the 3x 5A fuses for protecting the power connector pins from oxidizing and melting the connector plastic (we had some cases, when the connector ...
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153 views

Using thermal fuses in parallel?

If one has some 216C 10A thermal fuses, could one wire two in parallel in order to fuse a 10A heated bed on a 3d printer? The bed is 110V and 1100W btw, so in normal operation it should draw 10A. ...
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1answer
52 views

Can I use a simple fuse to protect a CMOS over current?

I'm designing an output with a MOSFET transistor to control loads such as relays, motors or incandescent lamps, similar to the outputs of a PLC. Obviously, there is no problem as long as the load ...
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2answers
36 views

Should I look at nominal or max battery voltage for choosing resetable fuse?

I am building a LED/Camera control circuit that is going to be using a 14.8V Li-Ion battery as a supply. I want to put a resettable fuse to prevent short circuits from blowing up too much since this ...
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2answers
748 views

Using diodes for reverse polarity protection

I want to protect my circuit against reverse polarity, by simply adding two diodes in parallel between the + and - input cables. So if the polarity is reversed, the current will go through those ...
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1answer
57 views

Trying to source a PCB component (a slow blow fuse I believe!)

I’ve stumbled upon this forum in a search for a replacement part for a PCB that makes up a digital ballast for a HPS light used in basil clone production. I’m handay with a soldering iron but I am ...
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1answer
270 views

Can I use a transistor like a fuse?

I just started learning about transistors, so I was wondering if I could build a circuit where short circuiting across the load caused a transistor to cut off power (like a fuse). My idea was that ...
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39 views

Suggestions on simulating fuse characteristics electronically?

Assume that we have an isolation transformer 230V in 230V out and that we measure the output current with a current transformer with known transfer function. We compare the current to a settable value ...
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1answer
83 views

Safety switch “breaking capacity” vs. voltage

In the context of safety switch rating (fuses, circuit breakers, etc.), the concept of breaking capacity refers to the maximum electric current which can be safely interrupted by a tripping safety ...
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2answers
79 views

Can i use 1 fuse for all the outputs to protect my power source from overcurrent?

Can i use 1 fuse for all the outputs to protect my power source from overcurrent by connecting the fuse to the ground wire? I have 3 outputs: 3.3V, 5V, 12V and i want to protect my power source when ...
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1answer
93 views

Does a 5A Car Fuse Blows in a 12 Miliseconds Peak of 6A, in a 220v Circuit?

Thinking here in using a 5A fuse in a certain circuit, but it may reach 6A sometimes for a mather of 10 or 12 miliseconds only. That way, would this fuse blow or it would sustain and blow only in ...
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1answer
122 views

20A or 30A fuse in 200A fuse clips — is nesting reducers OK?

So, I am trying to figure out the cleanest way to make a 20A or 30A tap from a 200A circuit (single hot + neutral) that is being run through a fusible safety switch (NEMA style, as this is in the USA),...
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1answer
140 views

Need to substitute a fusible resistor in an inrush limiter in a PSU

HP 6023A PSU again :) This time R1, which is a 20ohm 7W fusible. The relay pulls 1s after power is applied and I assume that the general idea is to take the egde of the rather substantial inrush into ...
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1answer
84 views

How to chose resettable fuse for 24 V DC to 5V DC converter?

I want to use a 24V to 5V DC converter, the PYBJ10-Q24-S5 (https://www.mouser.fr/datasheet/2/670/pybj10-om-1548233.pdf). Page 7 of the datasheet, they specified the EMC Recommended Circuit which ...
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1answer
467 views

Can I use a 24V, 1A fuse for a 5V application?

I have a 5V power supply which needs protection. I only have a 24V, 1A fuse. Can I use this fuse for the 5V power supply. As Watt = R * I * I = V * I. As rated W is constant for a given fuse, will ...
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1answer
112 views

How to choose the correct fuse in a double paralled battery supply system?

Suppose I have the following system: simulate this circuit – Schematic created using CircuitLab As you can see we have: Two 500V battery with an estimated 500mohm average internal resistance. ...
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1answer
167 views

Fast-blow instead of slow-blow fuse in consumer hifi power supply

I have a power supply unit for a hifi pre-amp. The power supply takes a slow-blow fuse (T2.5A/250V). If I use a fast fuse (F2.5A/250V) instead, how likely is the fuse to blow during normal power-on?
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Problem calculating fuses

I am calculating a fuse and I'm having a bit of trouble. I have a 12v 2A power supply that I want to protect, so my first thought was to place a fast 250v 2.5A fuse in series so it should blow if a ...
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2answers
385 views

Why a double fuse is used in some applications?

In some DC applications in an isolated system (i.e. no grounding), sometimes two fuses are used: one is positioned on the positive (Vcc) line while the other is located on the negative (return path or ...

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