Normally open and normally closed describe the contact state of a reed switch when the specified magnetic field is not acting on it. Choosing the correct form is important because the two types create different default circuit conditions.
A normally open reed switch has an open circuit in its normal state. When a magnet approaches with sufficient magnetic strength and the correct orientation, the contacts close and current can flow.
A normally closed reed switch has a closed circuit in its normal state. The specified magnetic field causes the contacts to open. This arrangement may be useful where the control system must detect a change from a continuously closed circuit.
The correct contact form depends on the controller input, required fail-state behavior and whether the magnet is present in the normal machine condition. The complete circuit should be reviewed rather than selecting only by the words open or closed.
Confirm operate and release sensitivity, magnet distance, contact rating, switching voltage, current, mechanical arrangement and expected operating frequency. Magnet shape, direction and mounting tolerance can change the operating point.
Reed switches are used in door sensors, level detection, security systems and industrial equipment. The exact contact form and sensitivity should be matched to the installation and control logic.
Browse the XURUI reed switch range for available series and model-selection support.
