Which of the following describes a Pressure Switch that is Normally Closed?

• A. Pressure Switch N.O.
• B. Float Switch N.C.
• C. Pressure Switch N.C.
• D. Pushbutton N.O.

Answer: (C)

A pressure switch that is normally closed (N.C.) means that in its default state, when no external pressure is acting on it, the electrical contacts are closed, allowing current to flow through the circuit. This configuration is used in various applications to ensure that a circuit remains energized until a specific pressure threshold is reached, at which point the contacts open and break the circuit.

This type of switch is often utilized in safety systems and control panels to maintain operation until a certain pressure condition indicates a need to deactivate or shut down a system, signalling that an action is required. Sensors of this nature are fundamental in automation and machinery to prevent operational failures or hazardous conditions.

The terminology of "normally closed" signifies the state that the switch is in when it is not being actuated or influenced by external conditions, which is integral to understanding how pressure switches function in practical applications.