Latching solenoids are a combination of an electromagnetic solenoid and permanent magnets. An electrical pulse is applied to the solenoid coil causing it to close. Once the pulse has finished the permanent magnets continue to hold the plunger in the closed position. To release the plunger, a low current pulse of opposite polarity is supplied to the solenoid coil. A return force is required for this operation and the fitting of a return spring can assist with this opening. The ability to hold in the closed position without the use of power makes the latching solenoid ideal for applications requiring continuous hold, or battery operation.
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