I am essentially intending to use this Schneider Electric A9F44120 MCB as an automatic brake for my wind turbine, which has an output of 25A @ 24Vac.
Can I use the normal 240Vac MCB for 24Vac?
Will it affect the current sensing ability or switching ability of the C.B? any suggests will be highly appreciated. Thanks  

  • \$\begingroup\$ Welcome to EE.SE. \$\endgroup\$ – Sparky256 Oct 24 '18 at 0:59

Whatever amp rating is on your breaker will hold true up to its voltage limit of 240 VAC. It is sensing only AC current, not the line voltage, and it does not care what the AC source is at long as it does not exceed the 240 VAC limit.

24 VAC is a bit low but enough so the breaker contacts behave correctly. They may not conduct current if the source voltage is just a few volts AC. If you have a datasheet on the breaker it should state minimum and maximum VAC limits.

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  • \$\begingroup\$ Hi Sparky, thanks for the reply. Its is A9F44120 (Schneider electric), and its datasheet does not say anything about its minimum or maximum vac limits, but only the rated voltage. I contacted Schneider Electric for this as well, but they were not sure. Any more suggestions ? \$\endgroup\$ – QasimFSH Oct 24 '18 at 1:16
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    \$\begingroup\$ None that would help, except that well under 1 VAC some breakers may not conduct current as expected, but all of your parameters are well within safe boundaries. \$\endgroup\$ – Sparky256 Oct 24 '18 at 1:20
  • \$\begingroup\$ Thanks Sparky, the same has been confirmed now by another rep. of Schneider. Thank you again for the swift response. \$\endgroup\$ – QasimFSH Oct 24 '18 at 1:25
  • \$\begingroup\$ Your welcome Qasim. \$\endgroup\$ – Sparky256 Oct 24 '18 at 1:27

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