In a pushbutton station, what does a normally open (NO) contact indicate?

• A. The circuit is open when the button is not pressed
• B. The circuit is closed when the button is not pressed
• C. The contact is always active
• D. The contact is used for low voltage applications

Answer: (A)

A normally open (NO) contact indicates that the circuit is open when the button is not pressed. This means that under normal conditions (when the button is at rest or not being activated), there is no path for current to flow, and therefore the circuit remains off. The NO contact changes state when the button is pressed, closing the circuit and allowing current to flow, which activates a connected device.

Understanding this functionality is crucial for designing and troubleshooting control circuits, as it allows the operator to ensure that devices only operate when intended. This type of contact is widely used in pushbutton applications where activation of a device, such as a motor or light, should only occur when the button is intentionally pressed by the user.

Other options incorrectly describe the behavior of NO contacts, such as suggesting that the circuit is closed when the button is not pressed or that the contact is always active, which misrepresents the purpose and function of an NO contact in a pushbutton station.