U NDERSTANDING L ATCHING S OLENOID T ECHNOLOGY W HAT IS A LATCHING - PowerPoint PPT Presentation

U NDERSTANDING L ATCHING S OLENOID T ECHNOLOGY

W HAT IS A LATCHING SOLENOID ?  A latching solenoid utilizes the electrical current pulse or internal permanent magnet material to maintain a set position without the constant application of power.  A bistable solenoid is another name often used for latching solenoids because they typically have two stable positions. Position #1: Solenoid is de-energized and plunger is fully extended Position #2: Solenoid is de-energized and plunger is held in position by permanent magnets

H OW D OES A L ATCHING S OLENOID O PERATE ? • Electrical polarity is important to obtain proper operation in a latching solenoid. • As current flows in one direction energizing the coil field, it adds to the pull of the permanent magnet making the armature attracted to the stationary pole. • Once the armature has moved full travel and is in contact with the pole, it will remain in a latched position without further electrical input. The armature is held in position by the permanent magnet. • To release from the latched position, the magnet’s attraction is cancelled by sending a current through the coil field in the opposite direction.

T YPES OF L ATCHING S OLENOIDS Permanent Magnet — Latching solenoids that utilize permanent magnets in conjunction with the solenoid coil to maintain the position of the armature when no current is applied. When a short pulse of electrical current is applied to the coil, a small magnetic flux is added to the permanent magnet and moves the plunger to the fixed pole piece. When the current is removed, the permanent magnet will hold the armature in the latched position. Applying a reverse polarity pulse will cancel the flux of the permanent magnet allowing the load or spring to release the plunger and move to the de-latched position.

T YPES OF L ATCHING S OLENOIDS Residual Magnetism — Much like latching solenoids that utilize permanent magnets, latching solenoids maintain the position of the armature when no current is applied. The solenoid uses internal design features to enhance the residual magnetism inherent to all DC solenoids. When current is applied, the solenoid will latch into position and hold utilizing the residual magnetism properties of the coil. The solenoid will remain in the latched position until a current of reverse polarity is applied. Once unlatched, the solenoid will not re-latch until power has been applied again.

B ENEFITS OF L ATCHING S OLENOIDS Latching solenoids can be turned off for most of the “on” cycle allowing the use of a higher current pulse which produces faster speed operation and generates a higher pull force without the excessive power consumption or heat generation of a conventional solenoid. While holding in either the on or off position, latching solenoids utilize almost no power, produce no heat and generate no electrical noise compared to conventional solenoids. Due to their low power consumption, latching solenoids are well suited for battery operated applications.