Questions tagged [fuses]
Questions regarding physical fuses. A fuse is 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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Rating of circuit breaker for protection
This circuit breaker is rated as 12V-48V 100A and I have to use this circuit breaker between additional alternator (24V 100A) in my vehicle and additional battery bank to provide overcurrent/short ...
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Fuses before or after vital components? [closed]
Why are fuses/circuit breakers usually placed right after the power supply and before any critical components? Fuses are designed to be the first thing that melts or breaks down when there's too much ...
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How to predict the voltage drop due to a fuse?
My device runs from a USB supply, typical 5V, current typically 20mA, never beyond 100mA.
I want to add a fuse. The JFC0402-0500FS claims rated current 0.50A (perfect for this application) and a ...
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Over-current/short-circuit protection for the battery bank
I am using a 24 V 100 A additional vehicle alternator for charging my additional battery bank of 24 V. I need an over-current/short-circuit protection for my battery bank. I am considering using a DC ...
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How can I identify this SMD part with F200 marking?
Can anyone help me to identify this SMD part?
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Did a blown fuse in my multimeter damage my multimeter?
May be a little newbie question, but I since I am an electronics beginner and couldn’t find a direct answer I will ask it.
I blew the 600 mA fuse on my brand new multimeter, I think I didn’t change ...
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Fuse at 250 volts versus fuse at 12 volts
I'm getting mixed answers. Will a 250 volts, 140 amperes fuse blow as fast as with 12 volts?
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Determining values when designing with thermal fuses; calculating influence of location/proximity to heat source & properties of protective coverings
The root question:
Are there any best practice rules or guidelines for spec'ing out a system with a non-resettable thermal fuse? What criteria is used to determine what rating fuse is needed?
I'm ...
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I purchased a box of car fuses ranging from 5 to 40 amps from EBAY. I want to test the fuse rating using dummy loads [closed]
I purchased a box of car fuses from EBAY. When testing the current draw on a new tire inflation pump, rated at 40 amps. I tested it using a 30 amp eBay fuse. The fuse started smoking, the fuse's ...
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Should the DC-DC and solar charging go through the main fuse or dedicated fuse?
I am planning a 12V dual battery setup to be used in a car. The aux battery is a LiFePo4 battery and it will be charged via a combined DC-DC and solar charger (50A, fuse 65A).
I want to add a fuse and ...
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Looking for an SMD fuse spare part marked with "PP"
I am bit out of ideas for this SMD fuse marked with "PP", where I can only find "P" ones. It's about 2x1mm in size. Does anyone have a clue what that is? Maybe its no fuse, after ...
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Can a small glass cylinder with "6.00" marking be a fuse?
My guess is that this part soldered to an SMD board is about 20 years old (it's from the controller of a Mecablitz 50MZ-5 wand flash). The controller currently is not working but that may be due to ...
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How to use blade fuse in DC circuit as protection?
While trying to add a protection to my buck converter circuit I came across Blade Fuses, which are faster at breaking compared to glass cartridge from what I saw. The question is, how is such a fuse ...
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Trying to locate a (resettable?) fuse that I believe may have blown entirely [closed]
I am led to believe that there is at least one (potentially resettable) fuse on this Bosch manufactured BMW PDC module. I am also led to believe it has a limit to the number of times it can blow and ...
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Audio amp board keep blowing fuses
I have a electronic piano that stopped working. After opening I case I found that one fuse on the amplifier PCB had blown. I replaced the fuses but they immediately blew again. I have investigated the ...
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Which value of fuse should I use?
So this 12 VDC LED rated at 1.5 watts i.e. 125 mA, The LED is run by a computer circuit which sends 12 V power to LED for on and off, exactly like a car turn signal blinker.
Which value fast blow ...
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Restrict current from a 9v battery to avoid blowing a fuse
I have an old landline telephone with a 250 V 250 mA fuse. It will not be connected to a landline, rather, I would like to power it using a 9 V battery (for use as a musical device... I do this with ...
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SMD PTC Fuse for 24 VDC
I am designing a new version of a PCB board with a microcontroller to drive two 24 V DC brushed motors, and I am looking for a self-resetting PTC SMD fuse for a 24 VDC supply line and max 2.5 A. The ...
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What is the point of triple JCASE automotive fuses?
Some JCASE automotive fuses come three in one enclosure. What problem do they solve? What do they do that three individual fuses couldn't do?
{My pictures}
The BUSSMANN MPF spec sheet (PDF) says;
&...
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Do letters matter on thermal fuses?
DIY oven repair question.
I need to replace this thermal fuse:
Does it matter what letters there are shown i.e. YCW.dz YCWRY, <...
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Why does the voltage over a fuse increase even though there is no current
I noticed during several fuse tests that when the current goes to zero (it might be that the fuse was melted down) the voltage drop over the fuse rises a certain period of time and drops down steep.
...
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What's the safety margin for replacing a ATX power supply fuse?
My ATX power supply stopped working. After opening it up and probing around (caps discharged), I discovered the 10A/250V fuse (white tube with leads) had blown. I have a ton of the common glass tube ...
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What does 'Minimum Holding Voltage" refer to for a Thermal Fuse?
One of the components I am looking at for a new design is a thermal fuse. In the documentation it refers to a "Minimum holding voltage". Source: https://www.bourns.com/docs/Product-...
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Fuse (I²t) ratings of copper cables
There are plenty of charts/calculators giving the maximal current for given wire section/gauge (they don't always give the same results).
Those ratings are for continuous current. If there is instead ...
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Location of Fuse and MOV
I have an AC module where the input is AC mains.
I am also using 2 AC-DC modules. AC-DC module 1 5V output & AC-DC module 2 12V output
Both these AC-DC modules requires fuses. I also want to place ...
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MOSFET SOA: Isn't the package current limit-line ambient temperature dependent?
Ref 1 says "The package limit-line will not change in case application conditions such as ambient
temperature vary"
As explained in Ref2, this limit is due to bond wire heating/melting.
If ...
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Circuit Protection: on-board vs off-board; manual vs auto. Which is better for our application?
RE: Circuit protection for small health & beauty product (for mass-production) similar to a foot spa whereby a portion of the user's body will come into direct contact with 1.5 gallons of water ...
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Do I still need a fuse if I'm using a GFCI?
RE: PD involving a small health & beauty product similar to a foot spa whereby the user will come into contact with water.
General description: Because malfunctioning foot spas have been known to ...
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Is this part a 1.1A 0805 self-recovery fuse?
I bought this online, It should be 1.1A 0805, but is it ? The pakage size is correct, Its 0805 but the value, I have doubts!
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What fuse can I use to replace this old glass tube fuse?
With what can I replace this old glass tube fuse?
Original fuse: glass tube fuse with the engravings "UEC 10A."
It is from a industrial motorized device perhaps 15-20 years old from Japan.
I ...
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What slow fuse should I get?
I had a fuse go in our old microscope. It says 125V 3 amperes on the top of the fuse. It is a slow fuse. This is what the broken one looks like. I have not been able to find the same part in my ...
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Replacing fuses on inverter PCB
I have an inverter that stopped working (after the 12 V DC power source was repeatedly connected and disconnected through a relay with a false contact). When I opened it, I saw some fuses that are ...
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Modified microwave oven transformer makes fuses blow upon powering without load
I have a microwave oven transformer (MOT) from an old microwave that I want to use as a step down transformer. Unfortunately, I destroyed the primary coil when removing it so I made myself a new ...
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Maximum load capacitance and rating for fusing for bridge rectifier
I'm looking for a replacement for an old bridge rectifier and I've found one (Vishay B80C1500G), but I'm curious about two parameters of the bridge rectifier:
Maximum load capacitance
Rating for ...
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Fuse tap direction. Please help me understand which way is correct
I have a car fuse tap and was wondering if it is directional and why?
Please help me understand from bottom 2 variations which direction should I install it and why.
Thank you!
Fuse Tap:
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Should I chooses fuse with a lower value than nominal?
I have found this sheet about fuses and it makes zero sense to me - a fuse rated 30A will only blow at 50A?
Does that mean I have to choose a lower value, like ~20A for my <30A application?
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Can I use PPTC fuses instead of light bulbs to make an adjustable A.C. current limiter?
In Adjustable-ac-current-limiter-for-output-of-variac-for-safe-circuit-testing, I asked about alternatives to using incandescent light bulbs to make an adjustable A.C. current limiter. The challenge ...
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What is the current industry practice regarding the impact of current-limiting fuses on arc flash calculations?
Suppose you have a panel. The arc flash incident energy for this panel is computed based largely on the available short-circuit current (SCCA) to the panel, and the protective devices upstream of the ...
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Replacement fuse specification
I have a lighting fixture with a blown fuse on the PSU PCB. The blown fuse fitted was a "T3.15AL250C" 932 (red-coloured) box fuse. I replaced it with a "T3.15A 250V CQ MST" of the ...
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Would a 20A, 12v fuse be functionally identical to a 1A, 240v fuse?
1Ax240V=240W
20Ax12V=240W
Assuming both fuses are of the same type, would they be interchangeable?
I'm aware that 240v fuses may not exist. I'm assessing the viability of substituting a 250v fuse with ...
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How can I protect a 12 V, 5 A circuit from high current due to short circuit condition?
How can I protect a 12 V, 5 A circuit against high current due to short circuit?
I have tried resettable fuses but they do not work as expected. I have tried MF-USML300/12-2. In actual application (...
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Overcurrent protection (at 4A 100V)
On the PCB I'm designing, the total power consumption might be as high as 86W (including output power), with supply voltage between 18 and 75V DC (it is OK not to allow full output power bellow 22V). ...
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Can I use a 3 A fuse to a 13 A wire?
I made an extension cable from a 3 A cable because I wanted a thinner cable.
The plug came with a 5 A, 240 V fuse but I replaced the fuse with a 3 A, 240 V fuse.
If the appliances I use take more than ...
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PSU input fuse selection doubt, related to buck DC-DC converter
Suppose a buck DC-DC converter, specified for 10~60V input range, that in the worst case it has 80% efficiency (0.8), that at its output, with 5V, the average current is 3A, but that peaks of up to 5A ...
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Placement of inrush current limiter and inductor filter with respect to fuse
I'm trying to assemble the input circuit of this power supply: https://gaptec-electronic.com/datenblaetter/5ACFEW_3.pdf
The recommended input circuit is as follows:
For space management reasons, it ...
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How to size a fuse to protect a component?
I am trying to verify that I have correctly understood how to size a fuse to protect circuit components.
Lets assume I have a resistor model series that can tolerate 60W for 1 ms according to the ...
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Obsolete DMM fuses - what are safe substitutions?
I have two DMMs that need new fuses to measure current.
The first DMM is a small Radio Shack cheapie that wants a 5x20 mm 250V ceramic fast-blow 0.315 A, the second DMM is a Triplett 1101 A (still a ...
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Multimeter fails to measure current but voltage, resistance and continuity measurements work fine. Is the fuse blown?
I am trying to measure the current of a pretty simple circuit consisting of an LED, resistor and 9V battery. As I said measuring the voltage, resistance, continuity works fine but the current ...
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Battery fuses breaking capacity: main and accessories
I am looking to size several fuses' breaking capacities on a battery circuit.
Let's consider F1 = 300 A; F2 = 20 A; F3 = 40 A.
Given the battery is high-power and can output several kAs, the main fuse ...
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Is it safe to briefly short the secondary of a power transformer to measure the maximum fault current at the primary?
I have a bunch of salvaged step-down mains power transformers (220V-240V primary voltage at 50Hz), with powers ranging from a few VA to maybe 100VA. In order to use them safely in my projects I need ...
