Question

how do mcb works in a circuit

Answer 1

When a current more than that which is safe is passed through the MCB ( Miniature Circuit Breaker) the current flow is broken or stopped.The switch comes down and it can be "reset" after rectifying the error.
 

Answer 2

ᴀɴsᴡᴇʀ࿐

ᴅᴇғɪɴɪᴛɪᴏɴ:-

ᴀ ᴍɪɴɪᴀᴛᴜʀᴇ ᴄɪʀᴄᴜɪᴛ ʙʀᴇᴀᴋᴇʀ ᴏʀ ᴍᴄʙ ɪs ᴀɴ ᴇʟᴇᴄᴛʀᴏᴍᴀɢɴᴇᴛɪᴄ ᴅᴇᴠɪᴄᴇ ᴛʜᴀᴛ ʜᴀᴠᴇ ᴀ ᴄᴏᴍᴘʟᴇᴛᴇ ᴍᴏʟᴅᴇᴅ ɪɴsᴜʟᴀᴛɪɴɢ ᴍᴀᴛᴇʀɪᴀʟ. ᴛʜᴇ ᴍᴀɪɴ ғᴜɴᴄᴛɪᴏɴ ᴏғ ᴛʜɪs ᴅᴇᴠɪᴄᴇ ɪs ᴛᴏ sᴡɪᴛᴄʜ ᴛʜᴇ ᴄɪʀᴄᴜɪᴛ ᴡʜᴇɴ ᴀᴄᴄᴇss ᴄᴜʀʀᴇɴᴛ ɪs ᴘᴀssᴇᴅ

ᴡᴏʀᴋɪɴɢ ᴏғ ᴍᴄʙ:-

ᴛʜᴇ ᴍᴄʙ ᴡᴏʀᴋs ᴀs ᴀ sᴡɪᴛᴄʜ ᴡʜɪᴄʜ ɪs ᴀ ᴍᴀɴᴜᴀʟ sᴡɪᴛᴄʜ sʜᴏʀᴛ ᴄɪʀᴄᴜɪᴛ ᴏʀ ᴏᴠᴇʀʟᴏᴀᴅ sɪᴛᴜᴀᴛɪᴏɴs, ᴛʜᴇ ᴅᴇᴠɪᴄᴇ ᴀᴜᴛᴏᴍᴀᴛɪᴄᴀʟʟʏ ᴛʀɪᴘs ᴡʜᴇɴ ᴀᴄᴄᴇss ᴄᴜʀʀᴇɴᴛ ɪs ᴘᴀssᴇᴅ.

ᴜsᴇs ᴏғ ᴍᴄʙ

1.ᴛʜᴇʏ ᴀʀᴇ ᴜsᴇᴅ ɪɴ ʜᴏᴍᴇ ᴀᴘᴘʟɪᴀɴᴄᴇs.

2.ᴛʜᴇʏ ᴀʀᴇ ᴜsᴇᴅ ɪɴ ʜᴇᴀᴛᴇʀs.

3.ᴛʜᴇʏ ᴀʀᴇ ᴜsᴇᴅ ɪɴ ɪɴᴅᴜsᴛʀɪᴇs.