Electrical Dual Parallel Fuses

[Jeff_O]

A 600 watt continuous 1200 watt surge current pure sine wave inverter I have I was cleaning dust out and had seen 2 fuse holders in parallel. Inserted into both fuse holders were 30 amp fuses.

I know where separately two fuses are used, for separate fused hot and ground. I accepted that it can better protect the circuit. If one can give more on this great, I would appreciate that.

Is there a reason that can be explained for paralleling fuses?

I do understand that in parallel the current that would split, would be close to equal through the two fuses. If that is correct then would just one fuse be essentially the same by doubling the amps. Don't use two 30 amp fuses in parallel, just use a single 60 amp fuses instead? They are available I would think.

I did search internet and didn't find something that was easily explaining parallel fuses, so thanks if you have answers.

 

[Bazzathemammoth]

Are you sure it’s parallel and not one for +v, one for-v (not to be confused with 0v)

 

[Tracy]

A 600 watt continuous 1200 watt surge current pure sine wave inverter I have I was cleaning dust out and had seen 2 fuse holders in parallel. Inserted into both fuse holders were 30 amp fuses.

I know where separately two fuses are used, for separate fused hot and ground. I accepted that it can better protect the circuit. If one can give more on this great, I would appreciate that.

Is there a reason that can be explained for paralleling fuses?

I do understand that in parallel the current that would split, would be close to equal through the two fuses. If that is correct then would just one fuse be essentially the same by doubling the amps. Don't use two 30 amp fuses in parallel, just use a single 60 amp fuses instead? They are available I would think.

I did search internet and didn't find something that was easily explaining parallel fuses, so thanks if you have answers.

If was probably assembled that way for service. 60amp fuses aren't behind the counter in a gas station. 30A ATO fuses are available nearly everywhere in North America.
Functionally there is no difference.

 

[Jeff_O]

If was probably assembled that way for service. 60amp fuses aren't behind the counter in a gas station. 30A ATO fuses are available nearly everywhere in North America.
Functionally there is no difference.

A large bus bar between all three. Positive input to both fuses. Positive output both fuses. OK so maybe as I thought 60 amp could be had easily in a blade fuse, but maybe not. An as far as both poitive and negative fuse, I hear some old cars still around with positive ground.

 

[Jeff_O]

Are you sure it’s parallel and not one for +v, one for-v (not to be confused with 0v)

That's a good point. The picture you see it is not. I expect there are circuits that would fuse a wall current input for the whole unit and if two supplies within were a positive and a negative supplies are created, they may have two more fuses. The inverter input 12vdc probably creates high frequency AC for efficiency and the toriod transformer steps up voltage. If not then it just gets it around 120vac and regulates it with 60hz for US. Pure sign wave helps a light box color organ kit I have for battery use many years ago at Burning Man event. A DC supply for an audio amp I had plugged into the inverter was a high frequency efficient one and it created noise that interfered with the lights triggered by the triacs. I went back to the old type wallwort and everything was fine. Much more modern electronics of other art pieces using ic2 bus with led that meld through multiple colors that towered 70 foot tall with guy wires was amazing to see. It was covered with thousands that a controller made shapes appear to move and this on the outside edge of a wire form. The form was like two cone bases back to back. Pointy end at the ground and the other pointy end up to the sky. You could imagine guy wire were definitely needed to hold it up.

 

[Tracy]

A large bus bar between all three. Positive input to both fuses. Positive output both fuses. OK so maybe as I thought 60 amp could be had easily in a blade fuse, but maybe not. An as far as both poitive and negative fuse, I hear some old cars still around with positive ground.

60 amp fuses are easily available, but not necessarily at the first place you stop. For something made to mount in a vehicle, assembling with parts available at every gas station, hardware store, walmart, and in a lot of glove boxes makes sense.

 

[Jeff_O]

I tried using my Craftsman True RMS 81079 Multimeter to measure the frequency of my Honda EU1000 generator without a load on it. It had a very wobbly frequency measurement in the range of around 2Khz. It varies a maybe 100hz up an down on that 2Khz.

On the other meter, the P3 brand Kilowatt Meter, it did read 59 to 61hz.

The wall current from power company worked fine on both meters.

I will try later to put a load on it like a light bulb, incandescent type as it is mainly resistance and not using any high frequency transformer.

Just side note, the Craftsman Meter did read 50 percent duty cycle right on the mark. It did not vary at all.

I will report back once I have the time to check the generator using a load and see if that makes a difference.

I was almost worried that I might had damaged the meter, but obviously if the power company wall socket measures correctly, then the meter is not at fault.

Also, if the generator measure frequency fine on another meter as I had done, then what up with this?

I have a USB Oscilloscope Scope, that also has storage capability, but using it I have to employ the use of a 100:1 probe to keep within the oscilloscope's maximum input voltage rating.

Just getting ready for Winter, so after checking the airfilter and oil level, I felt I would grad a meter to see how the almost 15year old is doing!

 

[Jeff_O]

I did put a good load on the generator of around 300 watts with a incandescent shop light. Then also the second light in the shop light pair giving basically pure resistance and 600 watt load.

Same problem noted.

The meter did have some bad contacts in the past I noticed when using other functions

I just disconnected leads and sort of burnished (not burn), the contacts in meter's function switch by moving the knob back and forth a while.

This helped the temperature function, but not the frequency function. The duty cycle function works fine though.

Not sure I will take it apart as I have another meter for frequency measurement. The high voltage probe and my USB oscilloscope I have found and dusted off.

################

On another issue with an amateur radio hand held, I looked to get a new battery pack. The radio is out of support and only is there one seller with aftermarket battery pack in stock.

The reviews and BBB have not shown well on the vendor.

If I could, as with past hand held radio use external power supply fused to limit current overdraw, just plug source in the same connector as used for the slow trickle charger that would be great.

Some radios do allow this please note.

This particular radio does state specifically that this would damage the radio and will not work.

Then I think if where the battery pack connects to the radio I would instead just hook up the power supply, could that be an answer.

A replacement battery I could possibly make myself is another idea.

Taking apart the battery pack and replacing the cells with new ones I thought might be possible.

In any case, that is tedious so maybe not.

The battery pack does have 3 gold contacts. Then I would figure that as a power supply does not have but two plus and minus contacts, it is most likely for a temperature measurement for the charging protection.

The battery pack when not charging might be able to use a power supply or maybe a bigger battery both fused to limit over current, but this is looking like a pita to me.

Such as right to repair and schematics to reference to, the free hazardous waste recycle day, may be the answer.
.

 

[Jeff_O]

I did put a good load on the generator of around 300 watts with a incandescent shop light. Then also the second light in the shop light pair giving basically pure resistance and 600 watt load.

Same problem noted.

The meter did have some bad contacts in the past I noticed when using other functions

I just disconnected leads and sort of burnished (not burn), the contacts in meter's function switch by moving the knob back and forth a while.

This helped the temperature function, but not the frequency function. The duty cycle function works fine though.

Not sure I will take it apart as I have another meter for frequency measurement. The high voltage probe and my USB oscilloscope I have found and dusted off.

################

On another issue with an amateur radio hand held, I looked to get a new battery pack. The radio is out of support and only is there one seller with aftermarket battery pack in stock.

The reviews and BBB have not shown well on the vendor.

If I could, as with past hand held radio use external power supply fused to limit current overdraw, just plug source in the same connector as used for the slow trickle charger that would be great.

Some radios do allow this please note.

This particular radio does state specifically that this would damage the radio and will not work.

Then I think if where the battery pack connects to the radio I would instead just hook up the power supply, could that be an answer.

A replacement battery I could possibly make myself is another idea.

Taking apart the battery pack and replacing the cells with new ones I thought might be possible.

In any case, that is tedious so maybe not.

The battery pack does have 3 gold contacts. Then I would figure that as a power supply does not have but two plus and minus contacts, it is most likely for a temperature measurement for the charging protection.

The battery pack when not charging might be able to use a power supply or maybe a bigger battery both fused to limit over current, but this is looking like a pita to me.

Such as right to repair and schematics to reference to, the free hazardous waste recycle day, may be the answer.
.

Update:

Actually the radio has 3 contacts.
The battery has 2 contacts.

The NiMh battery type, I then understand does not have the 3rd contact.

Lithium Ion battery pack for the radio does.

Maybe I may rebuild the battery pack with some fresh (year old) Nickel Medal Hydride cells that come with solder tabs.

 

[KenE]

The frequency difference in your meters is due to precision of one meter over the other. You likely have a ~2kHz frequency riding on top of the 60 Hz output frequency. One meter is sensitive enough to recognize the high frequency rider and the other is not. Generators notoriously put out dirty frequencies. If the meter has a precision adjustment than turn it down and you will get the ~60 Hz reading.