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Solenoid Design Considerations

Solenoid Life

When selecting a solenoid style, it is important to consider the life rating of the unit and to understand the factors that negatively impact the life of the unit.

Standard product life ratings

BTA: 100,000,000 cycles

Ultimag: 100,000,000 actuations

Rotary: 1,000,000 actuations

Tubulars: 25,000,000 actuations

Soft Shift: 10,000,000 operations

Open Frames: 50,000 to 100,000 operations (Consult factory for longer life of 500,000 or more cycles)

The actual life of a solenoid is greatly affected by the application and environment factors such as exposure to extreme temperatures, dirt, dust, etc. When used with a constant voltage supply, an increase in coil temperature reduces the work output and the life of the unit. Side-loading and stroke also play an important role in determining the life you can expect in your application. A simple, yet often overlooked method to improve solenoid life is to minimize the side load, such as mounting the solenoid so that the shaft travels along a vertical plane. Keeping the stroke as short as possible will also improve life. 

Solenoid Starting Torque or Force

When determining an application’s torque or force requirement, apply a 1.5 safety factor. For example: a load requiring 4.5 lb-in of torque should utilize a solenoid providing 4.5 x 1.5 or 6.75 lb-in of torque. Likewise, a load requiring 4.5 lb of force should utilize a solenoid providing 4.5 x 1.5 or 6.75 lb of force.

Solenoid Duty Cycle

Duty cycle is determined by: ON time/(ON + OFF time). For example: a solenoid is actuated for 30 seconds, then off for 90 seconds. 30 sec ON / (30 Sec ON + 90 sec OFF) = 30/120 = 1/4 or 25% duty cycle Ledex and Dormeyer solenoid products are rated for various duty cycles ranging from continuous to 10% duty.

Solenoid Maximum On Time

Maximum ON time for a particular application can be a factor which overrides the duty cycle rating. For example, at 25% duty cycle, the maximum ON time for a given solenoid might be 36 seconds. If, however, the solenoid is operated at a cycle rate which enables the unit to return to ambient temperature between ON cycles, then the maximum ON time is extended somewhat. In the above example, this extended ON time is 44 seconds. Refer to the individual model specification pages on our website or fax back system for complete duty cycle and maximum on time specifications.

Solenoid Power Requirements

Voltage applied to the Ledex and Dormeyer solenoid and actuator products must be matched to the coil wire size for proper operation. Our products are available in a wide range or coil wire awgs to accommodate your input power. Refer to the individual model specification pages on our website or fax back system for coil wire awg recommendations. Many other coil awg sizes are available. Please feel free to contact our application engineering department for availability.

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