Magnet-Schultz of America’s new Solenoid 101 series of blogs is designed to inform about the basic functions of solenoid products. We will start by tackling the fundamentals of solenoid terminology, function, and design. Future posts in the series will describe other MSA product categories and applications in a similar fashion, providing a quick and easy grasp of concepts. We will continue posting our more technical blogs, but want to make the full breadth of solenoid knowledge available to our visitors.

What is Duty Cycle?

Duty cycles are a commonly questioned solenoid specification. They can be expressed in several different ways, which can make it difficult to understand any particular manufacturer’s notation. Before we can compare the notations, we need to define the term. The duty cycle of a solenoid refers to the amount of time the unit can be powered before it may overheat. Depending on the notation used, there may also be a second time measurement used to express how long the unit must remain off before it can be powered again. The most common ways to express duty cycle are as a time measurement, a percentage, or by terms.

Time Measurement

The clearest way to define a solenoid’s duty cycle is to list both the on and off cycles in units of time. An example would be 100ms on, 300ms off. Measurements like these can be found on Magnet-Schultz duty cycle charts, which are attached to each product entry in our reference design catalog. The benefit of this notation is that it provides defined boundaries, but it doesn’t allow much flexibility. A part with a 100ms on,300ms off duty cycle may not require the full 400ms off time if you decide to only power it for 10ms. The other notations account for this discrepancy.

Percentage

Stating duty cycle as a percentage is a convenient way to shorten up the notation and it makes it easier for the buyer to select a part that matches the duty cycle required by their application. They can simply take the cycle times for the application and turn it into a percentage and match it to the appropriate solenoid. The number stated in the percentage refers to the on time and the remainder refers to the off time. It is important to note that a duty cycle percentage has scale limitations. You can’t run a 25% duty cycle solenoid for an hour and then leave it off for 3. The full on and off cycle generally needs to occur in less than 5 minutes. The duty cycle for the part referenced in Time Measurement would be 25%.

Terms

There are also a few terms used to describe general duty cycles.

• Continuous – On continuously without interruption for periods of about 30 minutes or longer.
• Intermittent – On for only a short time, usually not more than 2 or 3 minutes, then followed by an off time which is normally at least as long as the on time. This on time and off cycling can be repeated continuously over the total life of the Solenoid.
• Pulse – Extremely short on time. A duty cycle is normally in the 10% to 25% range. This is maximum input power for that size solenoid.

Magnet-Schultz of America specializes in custom engineering and manufacturing. Our engineers design with every performance aspect of the solenoid in mind. Function, size, longevity, power consumption, and cost are all considered. If you have any questions related to solenoid sourcing or manufacturing, please feel free to contact us. Browse past blogs for an in-depth look at solenoid functions and subscribe to notifications for future posts!