Looking at plugging the robot into a UPS to deal with power failures.
What size units have people found to be adequate? UR states the robot is 400W max, plus we have another possible 300 ~ 400 watts of peripherals (intermittent conveyors, camera, etc) attached.
Best way to monitor for power loss? Many of the UPS systems have USB communications for PC shutdown, but for the robot it seems that having a simple input into the robot that could be checked at the beginning of each cycle would allow it to complete the current cycle then stop if power has failed.
You have pretty much answered all your questions yourself.
You shouldn’t need more than a couple of minutes of battery power to safely shut down the application and robot. It all depends on the application, though.
At 800w power, that’s about 130wh for 10 minutes and a power capability of 800w (a little expensive). Alternatively, you can find a power meter and measure the highest power draw from the system when running, and then scale the UPS’ power delivery capacity with this.
You should find a UPS with a relay output. APC, for example, have UPS’ with SmartSlot options, where you can add a relay module.
Besides that, you’re right about the checking of the digital input on each cycle. You can also place the power check in a thread, so you’re able to stop the problem midway, if that is needed.
I haven’t had this system running production yet, so I’ll probably have to wait until we’re at that point to see what the worst case power draw will be.
We have several systems handling similar parts - on these systems the average power draw shown on the Log tab of the pendant never goes above 50W. I assume that’s just the arm - maybe includes the controller?
The conveyors will be the main unknown - 3 small conveyors, not likely to start/run at the same time.
Cycle time will be less than a minute, so I don’t need a long working time.
I’m pretty sure I’ll be able to get by with a fairly standard $100 - $150 computer style battery backup as far as capacity goes - don’t know if the robot wants a better sine wave than those give, and I don’t know if there are any out there which give a usable signal for power loss (I expect I can find some sort of separate sensor if necessary).
The SmartSlot type appear to be more of a rack mount style, which I don’t think I can make fit, and are significantly more expensive.
something tall and narrow would be ideal - such as the tower style, in order to fit where I’m hoping.
I was hoping there are people out there who are using these style systems with good luck.
You will have to make completely sure that the UPS can power everything at once.
The robot can run on a modified sine wave inverter.
I don’t know of a standard UPS with a relay signal when power is cut. Alterntatively, you can add a simple 230V relay in front of the UPS, which connects an input in the robot and can be monitored in the program.
Adding a relay to monitor the power status is simple enough - I’m kind of surprised that I haven’t found something pre-configured available online. Everything I’m seeing at a simple level is set up to sound an alarm or activate a warning light, with no obvious signal output.
At the other end of course are the units which will call you on your cell phone when the power goes out.
