I have a circuit for monitoring fan regulator speed change using ADC (as shown).

But the problem is:

  • In case input supply voltage (230V) varies due to some over-voltage or short circuit, is it affecting the output of current sensor?

  • Is it affecting the ADC value reading?

  • To overcome, is it possible to add any protection circuit or something else ?

enter image description here

  • \$\begingroup\$ this depends a lot on what your current sensor and ADC are. Also, I think someone else on here had the exact same circuit earlier today..... \$\endgroup\$ – Hearth Feb 12 at 5:08
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    \$\begingroup\$ Yes, are you and the person who asked this question working on the same project by any chance? \$\endgroup\$ – Hearth Feb 12 at 5:11
  • \$\begingroup\$ This depends on the supply of the microcontroller (or external ADC module, if any). If the regulator that supplies the digital modules reflects the fluctuations to its output then yes, that may affect the measurements. Also the grounding is very important here. \$\endgroup\$ – Rohat Kılıç Feb 12 at 5:13
  • \$\begingroup\$ @Hearth yes ..We are in same project \$\endgroup\$ – RAVI Feb 12 at 5:19
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    \$\begingroup\$ It is highly recommended to isolate the regulator from the power grid. This can be done by a transformer. Please provide a more detailed schematic of the "regulator" block. \$\endgroup\$ – thece Feb 12 at 15:47

How Supply voltage affects your ADC or current sensing module is depends on either they are connected.

If ADC and current sensing module is isolated from the fan supply voltage than it will not affect your system.

If it is connected to supply voltage than you can put some isolation circuits in your system like a filter circuit, transient filter etc.

  • \$\begingroup\$ I got many circuits from google but still have doubt \$\endgroup\$ – RAVI Feb 12 at 7:29

If your power line has a 1 second dropout, then your low-voltage power supply capacitor needs to store enough charge to keep the ADC supply (and Voltage Reference supply) properly working (regulating) for that entire second.

At 1 amp current (into your regulator), if you want only 1 volt sag (say from 12 volts to 11 volts) in the un-regulated voltage over that 1 second, then you need 1,000,000 uF of capacitance. Yes, that is ONE Farad.


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