Frequently Asked Questions

Solenoids

• What is a solenoid?
• What is the mechanical life of a solenoid?
• What factors must be considered when selecting a solenoid?
• Where are solenoids used?
• What is a Stepping Solenoid

Switches

• What is a section?
• What is the difference between shorting and non-shorting?
• What is an index angle?
• When should you use gold plating?
• What is the difference between current/voltage capacity and voltage rating?

1. What is a solenoid?

   A typical solenoid consists of the following main elements: a cylindrical coil, a steel or iron frame or shell, a steel or iron plunger and optionally, a stationary magnetic pole/travel stop. A magnetic field is generated within the solenoid by passing electrical current through the coil. The frame or shell surrounds the coil, providing a flux path. In effect, it focuses the magnetic field produced by the coil. The plunger, being made of highly magnetic material, reacts to the magnetic field by attempting to move to the centre of the coil. The plunger will travel to the centred position unless stopped by a load, which exceeds the solenoid's force capability, or the plunger contacts the stationary pole/travel stop. The force generated by a solenoid is dependant upon the current flowing though the coil windings.

2. What is the mechanical life of a solenoid?

   Maximum solenoid life is achieved when the pull force required coincides as nearly as possible with the force generated by the solenoid. Solenoids which develop substantially more force than is required are subject to excessive hammering which eventually may cause mechanical failure. To improve mechanical life, the load must be in line with the plunger and side loads must be kept to a minimum. Mechanical life in DC solenoids will be increased with the addition of an anti-bottoming feature. There will be a slight reduction in force caused by an internal air gap when an anti-bottoming feature is included.

3. What factors must be considered when selecting a solenoid?

   The following information should be determined to correctly choose a solenoid

   1. What is the linear movement needed?
   2. How much force is required to perform the operation?
   3. What is the space limitation for the solenoid?
   4. What is the duty cycle of the solenoid?
   5. What is the operating temperature range?
   6. Are there any special industrial environmental concerns?
   7. Is there need for additional circuit protection?
   8. What size lead wire and length of lead is required?

4. Where are solenoids used?

   Typical applications:

   • Automated teller machines - Locking and feeding
   • Automatic sorting equipment - Accept/reject gates
   • Automotive - Central locking and gear shift locking
   • Business equipment - Locking, feeding and motion control
   • Camera/photo equipment - Shutter control
   • Compressor controls - Valve operation
   • Computer Peripherals - Paper feed
   • Fluid Control/ dispensing - Valve operation/shut-off
   • Gaming machines - Coin validation, locking and motion control
   • Vending equipment - Coin validation

5. What is a Stepping Solenoid

   Stepping Solenoids are available in 12, 18, 24 and 36 position designs, with uni-directional and bi-directional options. Known for their high torque-to-size ratio, the key to their superior performance is the exclusive tooth clutch drive. It has a positive action, self-locking drive that contributes to a greater usable torque output. For friction loads the clutch provides a positive grip (no slip) when driving inertia loads. The drive also acts as a built-in electro-mechanical clutch brake to eliminate the natural tendency of overdriving at the end of step. Torque is further increased by the incorporation of a spring loaded ball detent, accurate to ±1°, nonaccumulative. This accuracy provides near perfect alignment of the internal inclined ball race assuring consistently high starting torque.

6. What is a section?

   A section (or deck or wafer) is what contacts are mounted on.

7. What is the difference between shorting and non-shorting?

   A shorting contact is also known as "make before break" and describes the action of the contact as you select your switch positions. The switch will momentarily "short position 1 and 2 together when you rotate from position 1 over to position 2. A non-shorting contact is also known as" break before make". The connection is momentarily broken when you rotate from position 1 over to position 2.

8. What is an index angle?

   An index angle is the number of degrees between each position.

9. When should you use gold plating?

   Gold plating contacts should be used when your product needs a longer shelf life. Also if the switch will not be actuated for a long period of time after installation we recommend the use of gold plating.

10. What is the difference between current/voltage capacity and voltage rating?

    Current carrying capacity measured in Amps, is the maximum load that this switch will carry with the contacts in a closed position. Current and voltage rating is the tested amperage capacity when you switch the contacts between positions under load when you switch between positions, an electrical arc occurs, Over a period of time, this arc causes contact wear. A switch with the contacts closed has no arc, and carrying capacity is higher.