What Is the Best Way to Finalize Your Power Supply Choice?

What Voltage Does the Actuator Require?

Start by checking the voltage listed in the datasheet for the exact actuator model.

Voltage options vary across Actuonix DC actuator families. For example, the L8 and L12 are available in 6 V and 12 V, while the P8 is only available in 12 V. You can also identify the voltage directly from the model number. For example, L12-10-210-6-S identifies a 6 V actuator, while L12-10-210-12-S identifies the 12 V actuator.

The power supply should match the voltage specified for that actuator.

Using a lower input voltage than specified will reduce actuator performance below the datasheet specifications. If an LAC is used, the supply voltage must match the rated voltage of the connected actuator. Review the LAC datasheet before finalizing the supply voltage.

Once the correct voltage is confirmed, the next step is to determine how much current the power supply needs to provide.

How Much Current Can the Actuator Draw Under Load?

The current drawn by a DC actuator changes according to load. As the load increases, the motor draws more current. Actuonix Current Curves show this relationship by plotting current against force. The curves also show how current draw differs between the available gear ratios.

The same current-versus-force relationship is seen across other Actuonix DC actuator models, although the actual current values vary by model, voltage, and gear ratio.

Even when two actuator models use the same rated voltage, their current requirements can be different. For example, a 12 V L12 has a published stall current of 246 mA, while the 12 V T16 has a published stall current of 1000 mA. Both actuators require a 12 V supply, but the amount of current the power supply needs to accommodate is different.

This is why the current requirement needs to be checked for the exact actuator model. The next step is deciding which current value to use when sizing the power supply.

How Much Current Capacity Does the Power Supply Need?

For a single actuator, the published stall current in the datasheets provides a useful maximum-current reference when checking the power supply. Stall current is the maximum current the actuator draws when it stalls against a hard limit.

For example, a 12 V L12 has a published stall current of 246 mA. A power supply selected for that actuator should therefore be able to provide at least 246 mA.

Stalling an actuator is not advisable because it can shorten actuator life. Stall current is therefore used as a reference for selecting adequate power-supply current capacity, not as the actuator's normal operating current.

How Much Current Is Needed When Several Actuators Share One Power Supply?

When several actuators operate at the same time, the power supply needs enough current capacity for their combined current draw. A simple way to check this is to add the stall current of each actuator that may operate together. Refer to the IoT Servo Shield datasheet and the Timer Relay datasheet when either accessory is part of the system.

For example, consider two 12 V PQ12 actuators. Each has a stall current of 210 mA at 12 V.

For multiple-actuator setups, Actuonix recommends adding approximately 20 to 30% to the total peak-current calculation.

The number of actuators that can operate together also matters. If all of the actuators can move at the same time, their current requirements need to be considered together. If the application operates them in sequence, the calculation should reflect the actuators that can actually be running at the same time.

What Changes When a Controller Is Used?

Adding a controller means the power supply needs to meet the requirements of both the actuator and the controller.

For example, an Actuonix P-series actuator used with an LAC requires an external power supply. The supply voltage must match the actuator’s rated voltage. The LAC operates from 6 to 24 VDC and is rated for 4 A peak current at a 10% duty cycle. Each LAC controls one actuator. The 4 A peak-current rating is a limit of the LAC, not the required power-supply current rating for every actuator used with it. The external power supply still needs to be selected for the requirements of the actuator being controlled.

Other Actuonix control boards have different power requirements. The Ext-R, for example, operates from 6 to 12 VDC and requires a power supply rated for at least 1 A. As with the LAC, the supply voltage must match the actuator’s rated voltage.

When a controller is used, check its power requirements along with those of the actuator before selecting the power supply.

Can Installation Affect the Actuator’s Current Draw?

The actuator’s voltage and current specifications do not change after installation, but the conditions it operates under can.

If the actuator draws more current after it is installed, the mounting or surrounding components may be adding resistance. Side loading, poor alignment, binding, or additional friction can increase the force the actuator needs to move the load.

Increasing the current capacity of the power supply does not correct these mechanical issues. Testing the actuator after installation helps confirm its actual current draw and can reveal whether the mounting arrangement or moving parts are placing more load on the actuator than expected.

How Do Stepper Actuators Differ When Sizing a Power Supply?

The power-supply guidance above applies to Actuonix DC motor actuators. Stepper models such as the P8-ST and S20 use a different motor and driver arrangement.

Instead of a DC motor stall-current specification, their datasheets specify maximum current per phase. For example, the P8-ST is rated for 256 mA per phase and is designed for use with a compatible four-wire stepper driver.

For these actuators, power-supply selection needs to take the requirements of both the stepper actuator and the selected driver into account. The stall-current method used for the DC actuator models should not be applied directly to a P8-ST or S20 setup.