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I am using a SCT013-30 current transducer to measure current to an AC line. I hook it up to an ADS1115 16bit Analog Digital Converter. I would like to know what happens to the signal when the AC line that I am measuring lets say get shorted out for a duration of 1-3 seconds (by this time the breaker should have tripped.)

will the transducer generate a very high voltage that might kill itself?

will the ADS1115 get blown up too?

How can I protect my ADS so it wont get damaged?

Wiring Diagram

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  • \$\begingroup\$ I would say, test it. Get one of these SCT-013's (as a free sample preferably), run a thick wire through it, charge up a few big energy storage caps, and short the wire across it to simulate a current spike. Have a 'scope looking at the output. The cap voltage can be gradually increased for higher current pulses. \$\endgroup\$
    – rdtsc
    Oct 22, 2019 at 21:44
  • \$\begingroup\$ i do not have those big energy storage caps, it would be much easier for me to buy a circuit breaker, and literally short some mains. But you know which is slightly dangerous \$\endgroup\$
    – Jake quin
    Oct 22, 2019 at 22:05

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That current transformer is isolated from the line. Nothing will happen to the sensor, ADC, or MCU. The AC line never connects directly to that sensor anywhere. The sensor just goes around a wire carrying AC current.

The one hazard is that you should NEVER run a current transformer without a load (a burden resistor) or else an extremely high voltage will develop across the output terminals. This sensor looks like it already incorporates one though (the "so-called built-in sampling resistor").

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  • \$\begingroup\$ The SCT-013-30 version comes with built in burden resistor. Yes you are correct, but what i am worried is a short circuit generates a theoretical infinite current right? , and transducer generates a voltage proportional to the current. So in that time frame will the transducer also generate voltage beyond what is expected? \$\endgroup\$
    – Jake quin
    Oct 22, 2019 at 20:34
  • \$\begingroup\$ @Jakequin Oh, I see your concern. Hmmm, I'm not sure about that but I think the core would just saturate so the voltage developed would be higher than what you normally see since I think the operating region of the current transformer is where the output is linear, before the core saturates. You could use a TVS diode or MOV to protect against that I guess. \$\endgroup\$
    – DKNguyen
    Oct 22, 2019 at 20:38
  • \$\begingroup\$ Oh you might be actually right the saturation voltage would keep my ADS from receiving over-voltage. Im not entirely sure transducer work, the wires on the coil of the transducer wont burn up right even exposed to infinite current? \$\endgroup\$
    – Jake quin
    Oct 22, 2019 at 20:51
  • \$\begingroup\$ @Jakequin Shouldn't be a problem. \$\endgroup\$
    – DKNguyen
    Oct 22, 2019 at 21:23
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    \$\begingroup\$ The AC wire will pass a large current (10kA) briefly, it will produce a large magnetic field that will saturate the CT core and then the secondary will produce whatever output it does at saturation. Since the CT is rated to 30A and 1V out I would expect saturation to be not far above that, less than 60A giving 2Vrms out, so 5.6V ok-pk, so an over voltage condition could occur. Perhaps consider using a string of diodes back-to-back to clamp it. \$\endgroup\$
    – Frog
    Jul 10, 2021 at 5:44

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