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My application has a max Amp draw of 56@24Vdc, if I use a Circuit Breaker that is rated 60A@48Vdc, will it "trip" 60A@24Vdc? If not, what do you suggest? The Minn Kota MKR-19 Circuit breaker is rated 60A@12/24/36V how is this possible (Ohms Law)?

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    \$\begingroup\$ It's the current that makes a circuit breaker trip. Most are based on electromagnets pulling on an iron armature (fast trip on very high current) plus a thermal element that opens slowly, allowing short-term over-current. \$\endgroup\$ – DrMoishe Pippik Oct 9 '18 at 0:14
  • \$\begingroup\$ Do you have an answer to my first question? Thanks! \$\endgroup\$ – nigel Oct 9 '18 at 0:37
  • \$\begingroup\$ Any breaker for the correct current, and at least the maximum voltage, should work. \$\endgroup\$ – DrMoishe Pippik Oct 9 '18 at 21:17
  • \$\begingroup\$ all major manufacturers will have published curves in data sheets for circuit breakers that show what current for what time will cause them to trip. Typically voltage is irrelevant. \$\endgroup\$ – MadHatter Mar 15 at 23:21
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Circuit breakers such as the Minn Kota MKR-19 you point to are rated to disconnect at a particular current …...not at a particular load power (V*A), so the voltage is not used as any part of the specified trip current.

The Voltage IS important however, since this tells you what voltage the breaker is rated to 'break' without sustaining damage at the rated current. This is normally to do with the ability of the breaker to extinguish any arc that might form. In high voltage breakers the design includes special non-conductive plates that increase the arc length which results in the arc dying out quickly. In low voltage breaker they may simply have a fast acting separation of the contact points over a distance incompatible with sustaining the arc.

There will always be an arc, and so breakers that have tripped many times do eventually erode the contacts which results in a higher voltage drop across them, and ultimately failure of the breaker.

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  • \$\begingroup\$ Do you have an answer to my first question? Thanks! \$\endgroup\$ – nigel Oct 9 '18 at 0:39
  • \$\begingroup\$ Yes, a 60A circuit breaker will work (at 60A of course) and since the breaker is rated above your working voltage should be just fine for 24VDC. \$\endgroup\$ – Jack Creasey Oct 9 '18 at 4:26

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