One of the most common questions we get at Rapid3D and similar trade shows is: “What UPS is best for 3D Printers?”. Like most things, it depends. A $300 Monoprice Maker Select probably isn’t going to be found in the wild on an online sine-wave output UPS. That said, there are a few questions to ask yourself when pairing your industrial 3D printer to a reliable UPS.

What problem am I trying to solve?

Power problems originate from 2 sources: Inside your facility and outside:
best ups for 3d printers problem sources

It’s easy to think that most power issues are coming from that power plant on the left, right? The lights flicker or you’re searching for candles; this is the most visual representation of power issues, but it’s only a small part of the problem.

3d printer problem sourcesSo if the printer is disposable and all we care about is occasional downtime from a thunderstorm or careening car, a big box UPS is probably fine. If the 3D printer is an investment or it produces critical prototypes or products, we have to dig deeper.

What is True Power Protection?

Power Protection keeps the power pumping when the power goes out AND protects the device from non-nominal power from within the facility. Even dedicated circuits with isolated grounds often share neutral wires with additional circuits; until 2011 the NEC allowed it and even still, most inspectors don’t know to look for it. From the NEC code book:
So if your machine is disposable or your installation site was built after 2011 AND you know for sure the electrician did not share neutral wires, you might be ok… unless your device has a connected ethernet port. Assuming the IT rack has a different ground location from the circuit feeding your printer, you probably have a ground loop. Ground loops cause communication issues and connectivity problems frequently; these symptoms are rarely traced to the power problem causing it.

True power protection is prepared to address all sources of electrical problems:

So, What Do I Need?

Your UPS needs to have all of these things:

1. Isolation Transformer

A low impedance isolation transformer creates a copper break between the incoming power and the printer. Damaging transients, harmonics and ground loops will never get through.

2. Battery Back-Up

To protect against power outages and voltage sags/dips, you need batteries in-line to keep the power flowing.

3. Sine-Wave Output

Don’t expect the SMPS to auto-magically rectify a cheap square waveform generated by a sub-par UPS. The fast rising and falling edges of the “modified side-wave” create noise that will be coupled to the DC busses. It is also a stress riser for capacitors and silicon components since there is a resulting current spike. In English: It is shortening the life of the your printer while also generating noise which can cause lock ups. A Sine-Wave is the same type of power that comes out of the wall. The UPS should be proving it too.

4. Noise Filter

Every UPS on the market lists “noise filter” as a feature. The reality is, unless the impedance is known, a noise filter cannot be attenuated to be effective. An isolation transformer creates predictable impedance so an effective noise filter can be implemented.

*Bonus*: Surge Protection

Many UPS systems advertise this as a primary benefit but most every consumer grade UPS will be destroyed with an inbound strike. The printer will be protected but the voltage was just shunted to the ground. If there are any other unprotected devices on the circuit, they are toast. An isolation transformer can absorb up to 6000V @ 500A non-destructively. This means the printer is protected, so is your UPS and everything else down circuit.

Standard UPS systems don’t do anything to impede surges below 300 watts.

What Should I Buy?

We’ve worked with some of the biggest 3D printing manufacturers in the world to answer exactly that question. The answer is a UPS that has all of the above and is sized to handle both the inrush and sustained load of the printer. We’ve developed 3-phase solutions with voltage step-downs that accommodate the 400V input required by some German-based manufacturers. We’ve private labeled solutions for OEMs to market the UPS as a single “Power Protection Solution”.  Whether you’re simple selling desktop 3D printers or large frame 3-phase 3D printers, we can help your team develop, field trial, market and sell a solution that will impress your customers. It’s what we do. Give us a shout and we’ll figure it out.