Structure And Preponderance

The keep solenoid is a power-saving DC solenoid combining the magnetic circuit of an ordinary DC solenoid with permanent magnets. The plunger is pulled by an instantaneous application of reverse voltage, held there even if the voltage is turned off, and released by an instantaneous application of reverse voltage.

• STC-K Type Solenoids
  These solenoids of a special construction display the largest attraction force of all the keep solenoids of the same class.
• STC-KN Type Solenoids
  These keep solenoids are designed with a silencing effect(3 dB more) without sacrificing the characteristics of the K type solenoids.
• STC-KD Type Solenoids
  These solenoids can hold the plunger in both right and left positions.
  (Custom-made)

Pull, Hold and Release Mechanism

A. Pull
At application of voltage, the plunger is pulled by the combined magnetomotive force of the built-in permanent magnet and the coil.





B. Hold
The plunger is held by the magnetomotive force of the built-in permanent magnet only.









C. Release
The plunger is released by the reverse magnetomotive force of the coil canceling the magnetomotive force of the built-in permanent magnet.

Drive Circuit

Fig. 1
Note: A resistance R is required when there Is difference between action and return capacities

Fig. 2
Note: A double coil type with an intermediate tap from the coil is available to your request.

Coil Types of Keep Solenoid
The keep solenoid comes either in a single coil type or double coil type.

A. Single coil type

• This type of solenoid performs pull and re- lease with only one coil, so that the polarity of the coil must be reversed at switching between pull and release. When the pull force is given priority and the power exceeds the rated power, the releasing voltage must be lowered. Or if the rated voltage + 10% is used, a resistance must be placed in series in the release circuit (This resistance will be specified in the test report on the pilot sample (s). )

B. Double coil type

• This type of solenoid, having a pull coil and release coil, is simple in circuit design.
• For the double coil type, please specify" Plus common" or " minus common" for its configuration.
• Compared with the single coil type of the same capacity, the pull force of this type is a little smaller because of the smaller pull coil space designed to provide space for the release coil.

Standard Specifications

• Insulation resistance: 50MO or above at 500VDC
• Withstand voltage : 500VAC (50/60Hz)for 1 minute
• Surface finish of plunger: Nickel plating (Fluorocarbon resin coating is available, which will lengthen plunger life but weaken holding force.)