How to Use Relays for 24 VDC Systems to Work With 12 VDC Actuators

In this Instructables, we’ll be covering how to use relays for 24 VDC systems to work with 12 VDC actuators. A pre-existing setup may come with a system that runs a different voltage value than the replacement actuator you had in mind. Most of our in-stock actuators are available with 12 VDC motors and would not be directly compatible with a system that uses 24 VDC signals or power. Custom manufacturing is possible for most models to have 24 VDC motors; however, customization results in longer lead times. Another solution is to use 24 VDC relays with a separate 12 VDC power source to allow for actuator control.

Relays make use of an electromagnet that when energized would mechanically pull a switch to change contact points. A low current signal at 24 VDC can run through the coil inside the 24 VDC relay to switch between the normally open node (NO) and the normally closed node (NC), in which each node can be connected to a 12 VDC source to power a 12 VDC device or actuator.

• 2 x AC-31-30-24 Single Pole Double Throw Relay (24VDC)
• 1 x PS-40-12 110-220VAC to 12VDC power supply with a current rating of 40A
• 1 x PS-20-24 110-230VAC to 24VDC power supply with a current rating of 20A
• 1 x AC-17 Wiring Kit
• 1 x PA-09 Mini Industrial Actuator (12 VDC actuator used for demonstration)
• 1 x RC-12 Momentary Rocker Switch (used to simulate 24 VDC control system)

Wire the pre-existing 24 VDC control system as follows:

· Connect Positive [+] Output wire to Pin 7 of Right Relay

· Connect Negative [-] Output wire to Pin 7 of Left Relay

· Connect Positive [+] Input wire to Positive [+] 24 VDC

· Connect Negative [-] Input wire to Negative [-] 24 VDC

Wire the 12 VDC actuator as follows:

· Connect Positive [+] Input wire to Pin 5 of Right Relay

· Connect Negative [-] Input wire to Pin 5 of Left Relay

Wire the 12 VDC power supply as follows:

· Connect Positive [+] 12 VDC to Pin 4 of Right Relay

· Connect Positive [+] 12 VDC to Pin 4 of Left Relay

· Connect Negative [-] 12 VDC to Pin 1 of Right Relay

· Connect Negative [-] 12 VDC to Pin 1 of Left Relay

Wire the 24 VDC relays as follows:

· Connect Negative [-] 24 VDC to Pin 8 of Right Relay

· Connect Negative [-] 24 VDC to Pin 8 of Left Relay

When no power is applied, both relay output is connected to the NC pins (0VDC), which is connected to the ground. Therefore, the actuator is receiving 0VDC from the relays, and it remains stationary.

When an extended command is issued to the controller, the Right Relay will receive Positive [+] 24VDC from the controller, and the Left Relay will receive Negative [-] 24 VDC. This will cause the Right Relay’s output to switch to NO pin (+12VDC), and Left Relay’s output remains at NC (0VDC). At this point, the actuator will receive +12VDC from the output of the relays, and it will extend.

When a retract command is issued to the controller, the Right Relay will receive 0VDC, and Left Relay will receive 24VDC. This will cause the Right Relay’s output to remain at NC (0VDC), and Left Relay’s output to switch to NO (+12VDC). At this point, the actuator will receive -12VDC from the output of the relays, and it will retract.

Since 24 VDC power is supplied from the controller through the relays, it will not go through the 12 VDC actuator directly; effectively bypassing the previous voltage incompatibility issue of the actuator.

Conclusion

If you'd like to browse our selection of linear actuators, motion control systems, and microcontrollers then please visit us at www.progressiveautomations.com for all your actuator needs! We can even build a custom actuator or control system for you based on your custom specifications with the help of our highly trained staff of engineers. You can learn more about the custom order process right here!

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