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 an electrical current.
The principle of operation is similar to all linear solenoids. When the coil is energized, the armature is attracted to the pole. Once the armature 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 armature in this energized position. This is similar to what would happen if a permanent magnet was placed on a piece of steel.
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 permanent magnet. To release the solenoid from the hold position, the coil field has to cancel the "holding" magnet's attraction. The current then needs to flow in the opposite direction than the original current flow that pulled in the armature in order to cancel the magnet.
Latching solenoids are available as either two or three-position solenoids. A two-position solenoid can utilize the holding force of the magnet material in both positions or use a spring as a return. A three-position solenoid utilizes magnet material to hold the armature to either of two sides and achieve a center neutral position by springs. Two and three-position solenoids can require two coils and therefore at least a three wire input and two different controller output signals.
A latching solenoid can be used in both short and long stroke applications. However, to improve efficiency the solenoid stroke should be minimized if allowed. |
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