ches2443
Member
- Location
- deal island, maryland
Will a 15 amp square D QO breaker trip at the same amperage if it is connected to a 24v volt dc supply? Isn't amperage amperage on matter want the voltage?
Will a high voltage breaker work on low voltage
- Thread starter ches2443
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noonan
Member
- Location
- Bucks County, PA
- Occupation
- Project Manager
Is the breaker rated for DC?
ches2443
Member
- Location
- deal island, maryland
The breaker has a sine wave on it. But doesn't say AC only.
ches2443
Member
- Location
- deal island, maryland
I believe a QOU is rated for 48V dc. But not sure.
gar
Senior Member
- Location
- Ann Arbor, Michigan
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- EE
090212-1559 EST
A QO breaker is a thermal device.
AC or DC produce the same heating effect for the same RMS current so long as we are not talking about higher frequencies. 1 mHz might produce different results than 60 Hz. Certainly by 10 mHz there would be a problem from inductance. From 400 Hz down there is probably no difference.
Extinguishing an arc might vary. DC might be worse because there is no zero crossing. A large DC inductive load might substantially increase the arc duration. Energy in the inductor has to go somewhere.
.
A QO breaker is a thermal device.
AC or DC produce the same heating effect for the same RMS current so long as we are not talking about higher frequencies. 1 mHz might produce different results than 60 Hz. Certainly by 10 mHz there would be a problem from inductance. From 400 Hz down there is probably no difference.
Extinguishing an arc might vary. DC might be worse because there is no zero crossing. A large DC inductive load might substantially increase the arc duration. Energy in the inductor has to go somewhere.
.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
In general amps is amps, so a breaker will perform per its thermal tripping curve regardless of AC or DC.
However the effect of short circuit amps are different. The magnetic portion of an AC breaker will usually not react properly to a DC fault. Check with the manufacturer for the adjustment factors.
And as others have pointed out, actually clearing a DC arc is often very difficult for an AC device. Most AC breakers have different voltage and AIC ratings when used on DC.
That said, most of the QO family of breakers are rated for use up to 48VDC.
However the effect of short circuit amps are different. The magnetic portion of an AC breaker will usually not react properly to a DC fault. Check with the manufacturer for the adjustment factors.
And as others have pointed out, actually clearing a DC arc is often very difficult for an AC device. Most AC breakers have different voltage and AIC ratings when used on DC.
That said, most of the QO family of breakers are rated for use up to 48VDC.
TwinCitySparky
Senior Member
- Location
- Minnesota
FWIW
Here are a couple pics of a 1970 Chris Craft Commander that I did considerable rewiring on. Note the twin factory mounted SquareD QO panels operating at 12VDC. These breakers were not specially rated.
I just like the second picture of the flying deck... :grin: This guy spent some coin.
Fun project.
Here are a couple pics of a 1970 Chris Craft Commander that I did considerable rewiring on. Note the twin factory mounted SquareD QO panels operating at 12VDC. These breakers were not specially rated.
I just like the second picture of the flying deck... :grin: This guy spent some coin.
Fun project.
Speedskater
Senior Member
- Location
- Cleveland, Ohio
- Occupation
- retired broadcast, audio and industrial R&D engineering
How well do they survive on a boat with all the moisture?
TwinCitySparky
Senior Member
- Location
- Minnesota
Surprizingly well for almost 40 years old. No corrosion. Its been stored in a heated storage facility and the panels are well placed so it all helps.
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