UPS system - surge load

[Ashful]

Years ago we just plugged the printer into a UPS that had enough surge load to carry the printer. We cycled the batteries a lot but it worked.

What tripped the UPS off the circuit?

Converting the circuit to 240V is an interesting idea, but unfortunately there are lighting circuits in other rooms tied to this one. Nothings impossible, but it’s surely not looking like the simplest of the options available to us.

WiFi adaptor for printer is in the mail already, and I bought material today to make a simple mock-up of the desk I’ll be designing to go into the adjacent room, which will hold this printer I’m the new location. We have a plan!

 

[fbelec]

keep in mind the printer that is drawing 10 amps is making the rest of the circuit voltage fluctuate and could cause some spiking on that circuit that you wouldn't see with the naked eye. now a ups for 10 amps is not going to be cheap. back to the printer if you were to put a amp probe on the circuit you would see it all over the place. definitely get it off the circuit with the pc if you have one. laptops are fine

 

[Ashful]

keep in mind the printer that is drawing 10 amps is making the rest of the circuit voltage fluctuate and could cause some spiking on that circuit that you wouldn't see with the naked eye. now a ups for 10 amps is not going to be cheap. back to the printer if you were to put a amp probe on the circuit you would see it all over the place. definitely get it off the circuit with the pc if you have one. laptops are fine

Yep, no issues. I'm an MSEE, so I know how to use an ammeter. ;-) In fact, as I implied before, the thermal time constant on a residential breaker is slow enough at 133% rating (20A on 15A breaker) that it likely wouldn't even trip... most of the time.

The UPS sizing wouldn't be a huge issue, I'm used to dealing with them for my job, my HPC's all run on 2200VA units as it may take hours to safely shut down a simulation job during an outage. But you are right that it's not a very cost-effective solution, when I can just move the printer 20 feet an have an available circuit. Just the weight of those damn SmartUPS towers makes me groan, think two mid-sized car batteries in a steel ammo box, as that's basically what they are.

The initial question was generated before I knew there was an OEM WiFi adaptor available for this printer, as there was no Ethernet wiring to the nearest available free circuit, and really no easy way to get it there (thru a giant stone cooking fireplace). Once I found info on there being an available full-function WiFi adaptor, and then even found one used for $20 on ebay, all the other options became suddenly much less attractive!

So, the printer is being moved to the next room, as soon as that WiFi adaptor arrives. This did involve the construction of two new desks for that room, one permanent that won't be built until December (our Amish furniture maker is back-logged), and one temporary that I'm building in my own shop right now. But, even with the printer, the kids will now have a lot more space to work at their computer, as they've outgrown the desk I had built for them several years ago.

In fact, this opened up enough space on my own desk, that I might even consider getting them the color inkjet they've always wanted. I hate the damn things, when I need to rely on them actually working every time, but wouldn't mind having one as a second printer for the kids stuff. I do believe I have enough capacity on this circuit to run an inkjet, just not the 10 amp heaters in a business laser printer.

 

[peakbagger]

What tripped the UPS off the circuit?

Converting the circuit to 240V is an interesting idea, but unfortunately there are lighting circuits in other rooms tied to this one. Nothings impossible, but it’s surely not looking like the simplest of the options available to us.

WiFi adaptor for printer is in the mail already, and I bought material today to make a simple mock-up of the desk I’ll be designing to go into the adjacent room, which will hold this printer I’m the new location. We have a plan!

A good quality UPS monitors the incoming voltage and not only does it switch to battery when the power goes out but it also switches to battery when the voltage drops in the supply circuit. A laser jet has a big heater element to melt the plastic ink to the paper and it requires a certain wattage. Watts is equal to Volts multiplied by Amps. If the Volts drops, the Amps go up and the breaker eventually trips. If the UPS internal inverter has enough capacity to supply the watts to the printer, the initial voltage sag in the house circuit from the printer turning on the heater will trip the UPS into UPS mode and it will usually stay there for some period of time before it switches back to the house current. That is usually enough to carry the printer through the heater mode. The other thing that factors in are that house breakers have trip delays built into them. The old fashioned versions had a coil of wire around a bimetallic spring contact (sort of the same idea as snap disk on pellet stove), the coil would be sized to heat up as the current in the circuit got to the breaker rating, if the current was sustained it would keep heating up until the bimetallic contact would spring open and break the circuit. This takes time. In industrial breakers the "heaters" could be changed out to vary the delay to deal with short term inrush currents. This is now done with solid state components.

The downside is UPS batteries are designed for "float" service, they are designed to sit there and do a deep discharge just a few times in their life. Repeated partial discharges tend to wear out the batteries more often. I had a large commercial computer system UPS I installed on a weird power supply (two phase power from an ancient hydro electric plant converted to three phase), the power quality was bad on occasion so the UPS would go into UPS mode frequently. Commerical and industrial UPS units tend to be hair trigger when detecting power quality, they would rather switch to UPS mode then miss allow bad or no power getting to the equipment. The computer was quite happy with the power out of the UPS but the UPS was cycling frequently. The batteries were supposed to last three years and we were changing them out every 3 to 5 months.

Note most home UPS's specifically recommend that laser jets not be hooked to them for this reason.

 

[Ashful]

Yep, again... I do this for a living, a kindergarten-level explanation of ohms law is not needed. But you do make a good point on the deep discharge lifecycle of the battery, that would've probably been the biggest problem, if I had gone forward with that plan.

The main issue I have with your assumptions about tripping the UPS is that the round-trip resistance of ~100 feet of AWG-14 Romex will be under 0.5 ohms, so the drop when the printer heater kicks in will likely be under 5 volts. Most UPS's can be set to trip at 10% or 5% drop from nominal or average voltage, so 12 or 6 volts on a 120V setting. Even with a more programmable UPS, I'm not sure there's a setting which can capture the heater kicking on, which is not going to be so sensitive so as to be randomly tripping from our regular voltage variation, not that this would necessarily be an issue to have it randomly kicking in more frequently.

In any case, I'm relocating the printer to another circuit. Unless that's found to be too inconvenient, I think we can close this one.

Thanks!

 

[gthomas785]

The main issue I have with your assumptions about tripping the UPS is that the round-trip resistance of ~100 feet of AWG-14 Romex will be under 0.5 ohms, so the drop when the printer heater kicks in will likely be under 5 volts. Most UPS's can be set to trip at 10% or 5% of load, so 12 or 6 volts on a 120V setting. Even with a more programmable UPS, I'm not sure there's a setting which can capture the heater kicking on, which is not going to be so sensitive so as to be randomly tripping from our regular voltage variation, not that this would necessarily be an issue to have it randomly kicking in more frequently.

At least when the breaker trips, the printer would keep printing

 

[DuaeGuttae]

In fact, this opened up enough space on my own desk, that I might even consider getting them the color inkjet they've always wanted. I hate the damn things, when I need to rely on them actually working every time, but wouldn't mind having one as a second printer for the kids stuff. I do believe I have enough capacity on this circuit to run an inkjet, just not the 10 amp heaters in a business laser printer.

I don’t have tons of experience with printers, but we bought an Epson EcoTank printer a couple of years ago, and it has worked really well for us. I use it somewhat frequently as I’m a homeschooling mom, and I print math pages and Latin quizzes and the like, but we’ve never had a problem with the ink drying out, even in a room that doesn’t have constant climate control in Texas. The Ink tanks are easy to refill and more economical than cartridges. It might be a good option for a printer for kids’ projects.

 

[peakbagger]

Ink jets are great but for speed and durability its hard to beat a laser jet.

 

[Ashful]

I don’t have tons of experience with printers, but we bought an Epson EcoTank printer a couple of years ago, and it has worked really well for us. I use it somewhat frequently as I’m a homeschooling mom, and I print math pages and Latin quizzes and the like, but we’ve never had a problem with the ink drying out, even in a room that doesn’t have constant climate control in Texas. The Ink tanks are easy to refill and more economical than cartridges. It might be a good option for a printer for kids’ projects.

Thanks, Duae! I’ll definitely check that one out, if we end up getting an inkjet.

That printer actually sounds like an old series of Canon inkjet printers I used to use at work, about 20 years ago. Unfortunately, Canon discontinued them, when they realized they were losing out on all the cartridge money made by HP and Epson.

The old Canons had four replaceable bottles that plugged into the inkjet carriage. The carriage contained the piezo and nozzle, and there were many aftermarket sellers for the ink at just a dollar or two per bottle. Nice system, but the nozzles would still sometimes clog, requiring a carousel replacement at $100’ish.

 

[peakbagger]

I have an older Epson all in one scanner, color inkjet printer, it just drank down yellow ink even though I rarely printed color. Apparently the printer prints an anticounterfitting code on every print it makes and uses yellow ink to do it. If it runs out of yellow ink it will not print at all. The only reason its still taking up space is its my only 11x17 scanner. I think they lost a lot of customers and has to come out with the ECO tank printers to try to get new customers.