Re: programmable circuit breaker

On 09-03-2025 23:21, Klaus Kragelund wrote:

On 06-03-2025 00:55, john larkin wrote:

On Wed, 5 Mar 2025 15:36:22 -0800, Buzz McCool <buzz_mccool@yahoo.com>
wrote:
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On 3/4/2025 9:06 PM, john larkin wrote:
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So how might a user program a circuit breaker? Just RMS current with
some time constant? Allow fast and slow trips?

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I've designed an electronic circuit breaker using Linear Technology
(now Analog Devices) hot swap controllers. It looks like they offer
some products with a programmable current limit.
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I'm not sure if you can change the circuit breaker time delay though.
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I used a TI e-fuse chip in one product. TPS26600. It liked to blow up.
Being a nasty power-pad chip, it was very hard to replace.
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AP22652 is cool. We use it to current limit the power into pulse
generator output drivers.
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On our relay board, we'll have a Hall effect current sensor driving a
fast ADC, and the shutdown will be FPGA code, so we can do most
anything.
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I am working on a solid state circuit breaker. So instead of your relay, I have two IGBTs back to back for ac operation.
 You can do more than just measure the current. I have added an inductor on the output, so in case of a short and umlimited power on the primary side, the current rises defined before saturation.
 You can detect the voltage over the switch/inductor, if too high you have a short. That will probably be much faster than the hall sensor
 The inductor will limited the dI/dt, so the IGBTs are turned off before SOA is reached. Kick back pulse must be diverted off course, when/if the load decides not to be a short any more at the peak of the current ramp.

About the relay, you can detect the armature position by measuring the coil inductance. So to have the relay act faster, operate the relay at the knife edge where the armature is just pulled in. Then when current is decayed, the armature is moved instantly