A magnetic latching solenoid is equipped with a permanent magnet that keeps the plunger in position magnetically when under no other force. With the internal permanent magnet maintaining attachment, only consuming power to reinstate attraction.

*The explanation of solenoids below is limited to our company’s products.

Magnetic latching solenoids are equipped with permanent magnets so during use,
 1. The pull force when de-energized
2. The electric current direction
3. The magnetic holding force
4. The return load and electric power
must be taken into consideration.

The de-energized pull force
The de-energized pull force refers to the pulling force applied to the plunger by the permanent magnet when the solenoid is de-energized.

The electric current direction
Similar to how magnets have N and S poles, a magnetic latching solenoid’s N and S poles are decided by the electric current direction. When under a pull force a current direction that does not repel the permanent magnet is necessary.
The current direction is listed in the catalog. For the above example, a positive(+) red lead and a negative(-) black lead is the correct current direction for suction.

The magnetic holding force
When the plunger comes into contact with the fixed core, even if the power is cut the considerable force of the permanent magnet maintains the retracted plunger position.

The return load and electric power
In order for the plunger to return, a current opposite of the above diagram is applied to repel the permanent magnet.
Electric power just enough to cancel the magnetic force of the magnet is necessary. If not enough power is applied, the magnetic force will not be cancelled, and if too much power is applied the solenoid’s magnetic force will win out over the magnet’s and end up pulling the plunger in.
Because the resistor, R, in the diagram above can dissipate a lot of power at the same voltage as when energized, the power is adjusted by mediating the resistance. Because the plunger does not return to its original position automatically – the return takes place when the magnetic force of the permanent magnet is negated – during use, a load must be applied to the plunger taking into account the pull force when de-energized.