Stop pushbuttons are normally closed contact configurations. Why?
What will be an ideal response?
A normally-closed contact pushbutton is used for the stop device, because under normal circumstances the control circuit power has to be passed on to the rest of the control devices in the rung if the Stop pushbutton is not pressed. The Stop pushbutton will always be the first device off of L1, so that it has “master control” of the rung, because all of the control circuit power to that rung must first pass through the stop pushbutton. No matter what else in the rung is closed or energized, pushing the Stop pushbutton will de-energize the entire rung. The Stop pushbutton only breaks contact between the two stationary contacts when the pushbutton is pressed, as soon as the pushbutton is released the contacts will close again.
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What will be an ideal response?