1A Automatic Breaker with Reset Switch

185

03:12:27

Increase the load to 55W to see it break. Reduce it back down to 50W and tap the reset switch to reset. Useful for applications where immediate circuit breakage is needed like to protect the power transistors of an amplifier in the case of a short.

published 8 years ago

rich11292000

8 years ago

Good circuit. 2 minor errors in terminology. 1. Breakers are not rated in watts, its rated in amps, amperage is measured in 1 hour. 2. This breaker is rated in coulombs, coulombs are rated instantaneously. A 1 amp breaker loaded to 1 amp will take 1 hour to trip. A 1 coulomb breaker loaded to 1 coulomb will trip instanlty. This coulomb style breaker mixed with amp/hour breaker would have significant safety features. My challenge for you: Build a amp/hour breaker. And also add some instructions on how to change the trip rating.

hurz

8 years ago

Very impractical circuit. It does its job only in simulation.

jason9

8 years ago

@rich11292000, a breaker like this might be used in conjunction with a high power audio amplifier so that the breaker can switch the moment power draw exceeds the allowed amount, protecting the circuit in case of a short before any significant damage can be done to the main power transistors. @hurz, how can this be made more practical? I'm only good at making circuits that work in the simulation. Please tell me how this circuit can be made more practical and the its current problems so that I can design better circuits in the future.

jason9

8 years ago

Updated the description.

jason9

8 years ago

@rich11292000 I have no idea how to make a timed breaker like you describe even if I could use very large (>100mF) capacitors without it being impractical. Also, the breakage rating is set by the combined resistance of the MOSFET (200-100mOhms) and the resistor in series with it (500mOhms).

BillyT

8 years ago

rich11292000, what curve breaker you are talking about.

rich11292000

8 years ago

A 30 amp double pole square d home line breaker has a secondary rating of 10kAIC. This doesn't mean the breaker will take an hour of 10kA before it trips. This secondary rating is measured in coulumb/sec. 100 coulumbs will trip the breaker in one second. If any more than 100 coulumbs flow through the breaker then it will explode.(hopefully) if not then you have a fire that you can't put out.

BillyT

8 years ago

The 10kAIC is the circuit fault current the device is designed to handle. If the final circuit is closer to the distribution transformer and the fault current for the circuit is above this, a higher rated device is required. This current has nothing to do with the device's designed trip current. The trip time is dependant on the device, whether it is thermal or magnetic, or a combination of the two, and the duration curve of the device. A magnetic device with a curve for electronic loads will trip faster than a thermal device with a trip curve designed for motor starting.

rich11292000

8 years ago

Gotcha

hurz

8 years ago

@jason9, build it, test it and see what it does for you!

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