Hi I have an induction heater and I want to install a electrical power fuse for the induction heater .

The heater runs at 13 amps .

My question is will the induction heater take more then 13 amps under Long operation hours ?

I am thinking of installing a 15 amp fuse for protection.

 

If it runs at 13A, then use 13A.

 

When you first turn the heater on....it will draw more than 13 amps. Usually a fair amount more. Put a 13 amp fuse in and see.
They make what is known as a slow blow fuse for these applications. They can take a short high current pulse without blowing.

15 amp slow blow should work.

 

The fuse should be rated for the wiring; i.e., a #12 wire can carry a 20 amp current. Fuses do not protect loads!

 

I don't believe so. A circuit breaker upstream has to do that. Protection has to be before the circuit.

I have never heard of rating a fuse to the supply conductor. That's new for me.

 

Fuses do not protect loads!

Up to some extent it does.

The fuse should be rated for the wiring; i.e., a #12 wire can carry a 20 amp current.

Fuse should be rated lower than the conductor. The upstream breaker which can be same size as fuse sometimes but not lower and not higher than the conductor rating

 

I'll bet linemen fuse their lines for max conductor current. But those lines are unique.....and I'll bet their current rating is comparatively higher than insulated wire. Plus they got the air cooling, I would think.

I don't know....never looked it up.

 

When selecting a fuse there are a number of considerations starting with the load. Things like the maximum normal current and working voltage come to mind. Then considerations as mentioned like will the load draw a large inrush current at power up? Fuseology is a good place to start. To answer your question:

I am thinking of installing a 15 amp fuse for protection

With a constant 13 Amp load I would consider a fuse rated for around 16 to 18 Amps but give the link a read. Induction heater circuits only draw heavy current when under a load. For example an induction heater stove current draw will be determined by the pot or pan placed on the stove. Choose a fuse about 125% of your maximum expected current.

Ron

 

When selecting a fuse there are a number of considerations starting with the load. Things like the maximum normal current and working voltage come to mind. Then considerations as mentioned like will the load draw a large inrush current at power up? Fuseology is a good place to start. To answer your question:

With a constant 13 Amp load I would consider a fuse rated for around 16 to 18 Amps but give the link a read. Induction heater circuits only draw heavy current when under a load. For example an induction heater stove current draw will be determined by the pot or pan placed on the stove. Choose a fuse about 125% of your maximum expected current.

Ron

Thanks so If lets say my heater is running under dry air condition the heater will only draw 13 amps and a 15 amp fuse won't be of use ?

I already have a circuit breaker upstream but i just want to use a fuse for extra protection .

I am just afraid that one day the heater will run with out any load and the heater itself will melt .

Thanks

 

Heaters should have a thermal cutoff mounted on it for over temp cutoff.

 

Thanks so If lets say my heater is running under dry air condition the heater will only draw 13 amps and a 15 amp fuse won't be of use ?

I already have a circuit breaker upstream but i just want to use a fuse for extra protection .

I am just afraid that one day the heater will run with out any load and the heater itself will melt .

Thanks

What I was getting at in my above post was that induction heaters will draw current dependent on the load. I used a induction heated cooking stove as an example. You would select a fuse type and rating based on the voltage and maximum load you can expect to see, also if a time delay fuse is required for any inrush current. If your absolute maximum current will never exceed 13 Amps at lets say 12 volts then I would consider a fuse and holder rated for 18 Amps @ 25 volts or something off the shelf in that area.

This would go better with a picture or good data sheet link to the induction heater in question. I just recently picked up one of these induction heaters to experiment with annealing brass rifle cases. I will initially limit my power supply current @ around 36 volts and see what I get, eventually fusing things at around 20 Amps using a fuse rated for my DC supply voltage. Trial and error while measuring my voltage and current should get me there. A link to what you have would be very helpful?

Ron

 

A fuse is NOT the proper solution to the concern here..

A safety/overheat temperature controller would be..

 

A fuse is NOT the proper solution to the concern here..

A safety/overheat temperature controller would be..

Where would you place the sensor for an induction heater which is what the original poster mentioned? Not like there is a heating element to place a sensor on. Here is an example:

The copper coil does not get hot, nor do the driver transistors. The load to be heated is placed in the Cu coil. So where would an overtemp sensor be placed?

Ron

 

Oh that...
I guess the coil won't over heat but the drivers will.

 

If it runs at 13A, then use 13A.

vaguely remember reading that a 13A fuse (for example) carrying exactly 13A, will fail after a specified time period. Its usual to include a safety margin.

As someone else pointed out - there's often a turn on surge to allow for.

 

Hello,

Have a look at the pages 5 and on of the attached PDF for selecting a fuse.

Bertus

 

Where would you place the sensor for an induction heater which is what the original poster mentioned? Not like there is a heating element to place a sensor on. Here is an example:


The copper coil does not get hot, nor do the driver transistors. The load to be heated is placed in the Cu coil. So where would an overtemp sensor be placed?

Ron

Thanks Ron.. Missed the "induction heater" part..

 

Thanks Ron.. Missed the "induction heater" part..

No biggie. Figured that was the case.

Ron

 

Peanut gallery here: I just have to chime in on this one!

Induction heat versus the old heat coil are vastly different animals. The old heat coil operates on high voltage and high current to produce the wattage needed to cook on ANY pan. Those use a large inrush of current until they come of temperature. Placing a cold pan of water on them drops their temperature and increases the amount of current being drawn. WORK is being done here. And with this "Work" comes wattage. Wattage is dependent upon voltage and current. So even an old heat coil will draw more current when you place a cold pan on it.

An induction heater works entirely different. They use magnetic eddy currents induced in the ferrous metal pot or pan. Depending on the magnetic fingerprint of the metal the induction coil will draw more or less power. To a very small degree, a cold pan will result in more eddy currents, and more WORK being done. (heating the pan) But it's the pan that gets hot, not the induction coil. OK, yes, the coil does get hot. That's why my induction cook top has a fan.

The original post asks about what fuse to use to protect the circuitry. I agree, fuses don't protect the circuit they protect the wiring. To a large degree ! ! ! HOWEVER, yes, fuses DO protect the electronics as well. Not too long ago I had a fuse blow on my amplifier. Had it not blown the whole amp could have cooked down to rubble. So fuses DO protect the electronics.

That being said, two things need to be considered when selecting the right fuse: First, how much current does the device draw in normal operation. By normal I mean the typical extremes it might see. NOT the sudden rush of some catastrophic event, just within the normal expected use of the device. You have an inductor rated at 13 amps. If for some reason the inductor should become internally shorted (hard or soft) the draw will go up. This will produce more heating in the inductor, which can cascade to rubble. A fuse is not a bad idea.

The second thing that needs to be considered is the wiring of the system. As someone before me said, a 12 gauge wire can handle 20 amps. Which is probably what your kitchen outlets are wired for (20 amps on 12 gauge wire). THAT is protected by the 20 amp breaker. The "RATING" for the 12 gauge isn't what the wire can handle it's what it can SAFELY handle under normal conditions. It can actually handle more, but that's why we have codes. Stick to what it's rated for and the breaker should prevent unintended fire from the house wiring becoming a gigantic heater, one that will warm your home to several thousands of degrees. So the gauge of the device wiring is also important.

Just guessing here, but your device might be wired with 14 gauge wire, which is UL rated to handle 15 amps. If your cooktop should malfunction (at 13 amps) it's likely it will pop the breaker. So it would appear that putting a 15 amp fuse in the device would be like putting a bandage over a bandage. The second bandage does nothing useful. BUT - - - There's nothing wrong with putting a 15 amp fuse in it. That will burn out before the breaker pops, so there may be some advantage to it.

Wanna put a fuse in? That's entirely up to you. And I don't think it's a bad idea; I just don't see it as a useful idea. Still, consider the wire gauge within the cooktop. If it is 14 gauge then a 15 amp fuse (or smaller) should be used. If the device draws 13 amps then a 13 amp (or larger) should be used. That leaves you a very small window of 2 amps either way. So I'd opt for the 15 amp fuse. IF I put a fuse in it.

What may be of MORE use might be a "Fusible Link" - a "Thermal Fuse" of sorts. It's purpose is to blow out if there is too much heat detected. But with a fusible link, once they blow they're blown. There ARE self resetting thermal switches, which you will find the likes of in your microwave or in your dryer (gas OR electric). If too much heat is detected they can shut down current to the heating element and let things cool off. Once cool they switch back on. BUT the caveat is knowing what the right temperature is. That I can't help you with. But I'm sure you can find thermal switches that will shut down under abnormal temperature excursions - such as if the fan fails or if the vent is blocked and heat builds inside your induction cooktop.

ME ? ? ? I leave that up to the engineers. If they didn't put one in then I'd accept that they probably know why they didn't. You might be well enough off to not modify the system at all. A fuse ? ? ? You'll have to replace it every time it blows. A switch ? ? ? It might shut down, but it comes back on when cool enough. Then you have power flowing again, and potentially more heat and a possibility of fire. If the machine is UL listed then I'd trust that.

[edit] This is in US house wiring standards. The UK uses 240 VAC systems and their wiring codes are probably different.

 

Peanut gallery here: I just have to chime in on this one!

Induction heat versus the old heat coil are vastly different animals. The old heat coil operates on high voltage and high current to produce the wattage needed to cook on ANY pan. Those use a large inrush of current until they come of temperature. Placing a cold pan of water on them drops their temperature and increases the amount of current being drawn. WORK is being done here. And with this "Work" comes wattage. Wattage is dependent upon voltage and current. So even an old heat coil will draw more current when you place a cold pan on it.

An induction heater works entirely different. They use magnetic eddy currents induced in the ferrous metal pot or pan. Depending on the magnetic fingerprint of the metal the induction coil will draw more or less power. To a very small degree, a cold pan will result in more eddy currents, and more WORK being done. (heating the pan) But it's the pan that gets hot, not the induction coil. OK, yes, the coil does get hot. That's why my induction cook top has a fan.

The original post asks about what fuse to use to protect the circuitry. I agree, fuses don't protect the circuit they protect the wiring. To a large degree ! ! ! HOWEVER, yes, fuses DO protect the electronics as well. Not too long ago I had a fuse blow on my amplifier. Had it not blown the whole amp could have cooked down to rubble. So fuses DO protect the electronics.

That being said, two things need to be considered when selecting the right fuse: First, how much current does the device draw in normal operation. By normal I mean the typical extremes it might see. NOT the sudden rush of some catastrophic event, just within the normal expected use of the device. You have an inductor rated at 13 amps. If for some reason the inductor should become internally shorted (hard or soft) the draw will go up. This will produce more heating in the inductor, which can cascade to rubble. A fuse is not a bad idea.

The second thing that needs to be considered is the wiring of the system. As someone before me said, a 12 gauge wire can handle 20 amps. Which is probably what your kitchen outlets are wired for (20 amps on 12 gauge wire). THAT is protected by the 20 amp breaker. The "RATING" for the 12 gauge isn't what the wire can handle it's what it can SAFELY handle under normal conditions. It can actually handle more, but that's why we have codes. Stick to what it's rated for and the breaker should prevent unintended fire from the house wiring becoming a gigantic heater, one that will warm your home to several thousands of degrees. So the gauge of the device wiring is also important.

Just guessing here, but your device might be wired with 14 gauge wire, which is UL rated to handle 15 amps. If your cooktop should malfunction (at 13 amps) it's likely it will pop the breaker. So it would appear that putting a 15 amp fuse in the device would be like putting a bandage over a bandage. The second bandage does nothing useful. BUT - - - There's nothing wrong with putting a 15 amp fuse in it. That will burn out before the breaker pops, so there may be some advantage to it.

Wanna put a fuse in? That's entirely up to you. And I don't think it's a bad idea; I just don't see it as a useful idea. Still, consider the wire gauge within the cooktop. If it is 14 gauge then a 15 amp fuse (or smaller) should be used. If the device draws 13 amps then a 13 amp (or larger) should be used. That leaves you a very small window of 2 amps either way. So I'd opt for the 15 amp fuse. IF I put a fuse in it.

What may be of MORE use might be a "Fusible Link" - a "Thermal Fuse" of sorts. It's purpose is to blow out if there is too much heat detected. But with a fusible link, once they blow they're blown. There ARE self resetting thermal switches, which you will find the likes of in your microwave or in your dryer (gas OR electric). If too much heat is detected they can shut down current to the heating element and let things cool off. Once cool they switch back on. BUT the caveat is knowing what the right temperature is. That I can't help you with. But I'm sure you can find thermal switches that will shut down under abnormal temperature excursions - such as if the fan fails or if the vent is blocked and heat builds inside your induction cooktop.

ME ? ? ? I leave that up to the engineers. If they didn't put one in then I'd accept that they probably know why they didn't. You might be well enough off to not modify the system at all. A fuse ? ? ? You'll have to replace it every time it blows. A switch ? ? ? It might shut down, but it comes back on when cool enough. Then you have power flowing again, and potentially more heat and a possibility of fire. If the machine is UL listed then I'd trust that.

[edit] This is in US house wiring standards. The UK uses 240 VAC systems and their wiring codes are probably different.

Its nominally 220 or 230V, but they fiddled the tolerance span to bring it into line with the specification on the continent. It usually ends up close to 240V.

Live is brown, neutral is blue and earth is green/yellow. It used to be live is red, neutral is black and earth is green. Last time I bothered looking at the building regs; house wiring used the old colour code - that could've changed since.