W223N735 Saratoga Drive
Waukesha, WI 53186
262-970-8660
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LATCHING SOLENOID OPERATION
Latching solenoids utilize the electrical current pulse, or internal permanent magnet material to maintain a set position without the constant application of electrical current.
The principle of operation is similar to all linear solenoids. When the coil is energized, the armature, (internal movable component), is attracted to the pole, (stationary within the solenoid body). The advantage of a latching solenoid is that once the plunger has moved full travel, (and is in contact with the pole), it will remain in this energized position without any further electrical power input.
This holding feature is accomplished because the resident magnetic material creates a field that maintains the plunger in this energized position much as would happen if you placed a permanent magnet on a piece of steel.
You can have two or even three position latching solenoids. A two-position device can utilize the holding force of the magnet material in both positions or use a spring as a return. A three-position device will have magnet material holding the armature to either of the two sides and achieve a center neutral position by springs. Two and three position devices can require two coils and therefore at least a three wire input and two different controller output signals.
Latching solenoids are different than traditional solenoids in that the electrical polarity is important to obtain proper operation. With current flowing in one direction, (as when energizing the solenoid), the coil field adds to the pull of the magnet. To release the solenoid from the hold position, the coil field has to cancel the "holding" magnet attraction and therefore the current has to flow in the opposite direction to the original pull in flow.
A latching solenoid can be used in both short and long stoke applications, but to improve efficiency, the solenoid stroke should be minimized if allowable. |
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