Uninterruptible Power Supply (UPS) and Actuators

This FAQ will provide information on why a UPS should be considered to be used with an actuator platform. It contains the following topics:

• What is a UPS?

• Why is important to have a UPS for a motion platform that utilizes actuators?

• What could cause the input power source to fail?

• What should be connected to the UPS?

• Where should the Thanos controller be connected?

• What UPS rating should be utilized?

• Potential negative of using a UPS with an actuator platform

• Should any additional UPS features be utilized?

• What should I do if a power source fails and the UPS activates?

• Additional Resources

What is a UPS?

It’s an uninterruptible power supply or uninterruptible power source (UPS) device that provides emergency power via batteries to power a load when the input power source fails. Popular manufacturers are APC, CyberPower and Tripp.

Why should you use a UPS for a motion platform that utilizes actuators?

When an actuator is on, the servo motor utilizes energy to hold its position as instructed by the Thanos controller. This is how the actuator moves, holds position, and raise or lowers itself into a parked position.

If the power is cut off unexpectedly to the Thanos controller which is providing guidance to the actuator -OR- power is cut directly to the servo drivers, the servo motor is no longer able to hold the slider within the actuator in place. The slider will then fall uncontrollably down the ball screw slamming into the bottom of the actuator lowering the motion rig violently at the same time. If this occurs, it could potentially damage the actuator and/or cause personal injury.

By having a UPS providing emergency power when an input power source fails, it will be able to continue to provide power to the Thanos controller and the servo drivers in order for the Thanos controller to lower the platform safely back into the parked position. The UPS could also be utilized to power your computer so you can close programs and safely park the platform.

What could cause the input power source to fail?

• Excessive load on the circuit could cause a breaker to trip, thus cutting power.

• Accidentally turning off a power strip while the platform is active.

• A power outage in the area due to weather or other events.

• Suddenly disconnecting the USB cord or cutting the power to the Thanos controller

• Suddenly shutting down the PC that the Thanos controller is utilizing for its power

• Voltage and Wattage draw that exceeds the specifications of the UPS

What should be connected to the UPS?

• The primary power connection that is providing power to the servo drivers and actuators

• The Thanos controller via a Powered USB Hub
  

For an actuator motion platform, the above two items are absolutely essential to allow the platform to return to a parked position after an input power source fails. The Thanos controller should be connected to the UPS via a Powered USB Hub. It is also recommended by Thanos to only have the Thanos controller connected on the Powered USB Hub to avoid any potential conflicts or electrical draw, thus a smaller Powered USB Hub can be utilized.

• Your PC

Your PC is not as critical as the first two items listed. A key factor to consider is the the overall expected load on the UPS. If the load is too high, the UPS might turn off. Since an actuator platform can utilize a high level of wattage under extreme load, only utilizing the UPS for the servo drivers/actuators along with the Thanos controller will provide a higher level of protection. A second UPS could be utilized for your PC.

Where should the Thanos controller be connected?

There are basically two options:

• Connected to a Powered USB Hub that is connected to the UPS

• Directly to the PC that is connected to the UPS

If the Thanos controller is connected to a Powered USB Hub, the Thanos controller can park the actuators during a power source failure as it does not require a PC connection. A Powered USB hub must be utilized and connected directly to the UPS. In addition, Thanos recommends to only have the Thanos servo connected on the Powered USB Hub to avoid any potential conflicts or electrical draw. Note: The same issue with unexpected power loss can occur with the Powered USB Hub if it is accidentally disconnected or turned off if the platform is active.

If the Thanos controller is connected to your PC, ensure the PC is connected to the UPS. If you are unsure if your PC continues to provide power to your USB devices when turned off, a Powered USB Hub might be a better choice. This would also mitigate the risk if there is an unexpected failure of the Power Supply Unit (PSU) in your PC. In addition, your PC will contribute to the overall load on the UPS.

What UPS rating should be utilized?

UPS devices are basically broken down into two rating: Volt Amps (VA) and Wattage (W). Typically, they can range from 850VA/510W up to 1500VA/900W. There are models that go lower and much higher. What specific rating you purchase is determined by your budget and how much power is needed.

A critical thing to remember is that if the power draw from the UPS is GREATER than the rating, it is very possible the UPS will shut down. This will immediately cut power to the Thanos controller and the actuators leading to a violent descent. This could occur if all devices are pulling peak power (PC, graphics cards, actuators, Thanos, and any additional accessories will all add to the power draw from the USP). Note: Actuators can peak in power draw if extremely fast motion on many different axes is required in a short period of time. This is more likely to occur if a high Spike Filter setting is utilized.

Utilizing a UPS with a higher rating is recommended. A 1500VA/900W should be sufficient for most systems. If a larger load is utilized or a large power draw is expected, a higher rating should be utilized or that a UPS is not utilized at all.

Potential negative of using a UPS with an actuator platform

As mentioned above, if the power draw from the UPS is GREATER than the rating, it is very possible the UPS will shut down. Here are a couple things that could cause this to occur:

1) Not knowing how much the maximum draw will be for your platform. Though actuators are very efficient in terms of power utilized (See the videos below for Normal and High Loads), there can be situations in which the power draw is extremely high. For example, a 4 actuator platform that is moving quickly with long strokes could utilize 300 watts of power or more. Adding additional actuators (6 DOF) could raise that up near 600 watts or more. If there are additional loads on the battery, such as a powerful PC, it could lead to the UPS being overloaded and switch off. In these cases, its recommended to ONLY have the Thanos controller and actuators connected to the UPS.

2) An actuator becomes stuck due to a coupler breaking, stuck slider, or any other mechanical issue.

If this occurs, the actuator will attempt to still move the platform. Actuator motors are EXTREMELY strong and can consume up to 4x750 watts of power per the SFX-100 Power Consumption Details linked at the bottom of this guide. Though the mechanical issue should be resolved immediately, when the break occurs, the power spike could cause the UPS to overload and turn off, thus dropping the platform.

The risk versus reward should be considered when adding a UPS to your actuator platform. If your location encounters frequent power outages, then a UPS might be a good decision. If you rarely encounter power outages and have a DIY platform, perhaps bypassing a UPS and utilizing other means (such as rubber pads or suspension straps for hexapod systems) would be the best choice.

Should any additional UPS features be utilized?

Sinwave, Automatic Voltage Regulation (AVR), and other features are completely a personal choice. However, reduction of electrical abnormalities could potentially reduce EMI or other electrical issues in your motion rig and when using VR.

What should I do if a power source fails and the UPS activates?

Most UPS will have an audible alarm notifying you it has activated. Quickly exit the platform and return the actuators to their parked position and shut down your system.

However, since many have loud audio systems, headphones, or play in VR, it could be possible you do not notice the UPS has activated. Depending on the power draw on the UPS, you could have only a few minutes to park the actuators and shut everything down. Most UPS will provide additional electrical outlets to act as surge protection for other devices and will not be powered by the battery if a power source failure occurs. These sockets can be utilized for other equipment on your motion platform that will turn off when the power is cut; thus, notifying you a power source failure has occurred and allow you to quickly park the platform and shut down your system.

Additional Resources

SFX-100 Power Consumption - Normal Load GT3

SFX-100 Power Consumption - High Load F1

Unexpected Power Loss Due to UPS Overload from Error in Spike Filter

SFX-100 Power Consumption Details

Scroll down to the Power Consumption section here.