Laser Printer Causing Voltage Drops

Hello, First several things come to mind. Have you tried to relocate the offending printer to a different electrical circuit from the one feeding the ups units. Second if the circuit feeding the ups's could be at its maximum load or the electrical cable from the panel could be long. This would make it more likely to allow for a heavy load to create a voltage sag that you are seeing.

It may be best to bring in a electrician to inspect the panel and load balance the electrical/computers systems and to inspect that you have the proper feeds to your computer room. Especially if you have upgraded your equipment over time from the original setup. It's possible you may have exceeded your power requirements from the original design.

Charles

metalSmith's

I am the electrician, and yes I've relocated that printer and it causes the voltage drop regardless. And I thought that the length of your cable, mc or whichever type of conduit you're using only affencted in a linear way. Meaning, if you have a voltage drop of 3 volts in a run of 200ft it will remain that way. This voltage drop variate for seconds, from 5 to 15 volts in 2 seconds every 4 to 10 minutes. And if the power balance was the case, wouldn't the breaker be tripping?

Bingo.

I had this issue with a copy center a few years back. Someone had snuck under the raised floor and plugged it into one of my facility UPS branches.

These devices can also create a ton of harmonics, which is not good for circuits where you don't want them.

There is no reason to even have Printers on the UPS, I would put them on the normal mains. What should be on the UPS are the PCs, the screens, communication stuff and any external storage......

If power drops off it is better to be able to shut the PCs down in an orderly way, ergo. no printing.

If printing is required with no mains, then I see two possibilities for you:-

1) Up the size of the UPS dramatically till these heaters make no difference at all to the voltage.

or

2) Run the printers on a second UPS, one that is not so sensitive either....

I personally do not like the "switchover" type UPS for sensitive electronic equipment. I prefer the ones that are basically an inverter running continually off a battery, that is being recharged all the time from a battery charger......simpler too.....no switchover.....

In practise, the battery charger is supplying the inverter, so you will have losses. Make sure the battery charger does not overcharge the battery, say not more than 13.5 volts or so.....I personally charge my batteries only to 13.2 volts, which means I only have about 70% of the max available charge, but the batteries last almost forever.....

The standard rule of IT is NEVER connect a laser printer to a ups. All laser printers have very high surge currents and are a big problem for any electrical circuit not rated high enough. Feed your lasers from dedicated circuits. Just make sure the grounds on these circuits are the same grounds used by whatever feeds them. That will keep you from having problems like blowing interfaces during storms, etc. Most of the time, a laser quitting (perhaps because of power loss) causes no problems for the computer that is trying to print at that time. A UPS designed to handle a laser printer is an expensive device. Let alone one big enough for three!

It is not at all clear whether you have the Laser printers powered by the UPS. As Andy and Rebuilt have already said, there is no reason to have them backup powered, as long as the computer(s) is(are). It should be standard procedure to ALWAYS save any documents before printing them, so if power should be lost, the documents are still on the computer(s), even though the documents in the printer queue are not printed until restart of the system.

If these are high speed laser printers, each one should be on its own circuit.

Indeed, the laser printers aren't connected through the UPS. Through the UPS I only have the servers and other sensitive equipment, which don't overload the UPS outlets. The printer is connected in another outlet, in a different circuit already, that goes to the same panel. I have 3 different circuits, on with a dedicated ground and one that is just a normal receptacle. The printer among other equipment is connected to either, and this printer, everytime is disconnected, makes the UPS work without and switching on and off to battery or line use. It's the entire circuits and circuit that are affected with this constant voltage drop. I had a reply that actually called my attention a lot, and I appreciate all of them, however, when you have a voltage drop due to the length of your wire, isn't this voltage drop supposed to be a constant drop? let's say you have 125v in terminal A and with a length of X feet you get 118v on terminal B, and it remains as a constant. In this case with this printer, I have a voltage drop of 5 to 15 v every 4 to 10 minutes which lasts 1 to 2 seconds. Could this still be a problem with my circuits length? or wire gauge? I thought wire gauge was strictly related only to the amperage which is strictly related to the loads. And my last question is, should I consider getting a stabilizer? I appreciate again every reply, I apologize for not being specific on the fact that the laser printer wasn't connected to the UPS. I shall be waiting for more, regards

Yes, a constant current draw will provide a constant voltage drop. However, laser printers do NOT draw a constant current. The current fluctuates over a wide rage.

More than 1 laser printer on any single 20A circuit can cause voltage problems.

If you can verify that a voltage drop is occurring AT the panel, then you need to evaluate the system from the panel back to a transformer or the pole. If panel is 3-phase, it may be as simple as redistributing some of the building loads (including the laser printers) more evenly between the 3-phases.

Could this still be a problem with my circuits length? or wire gauge? I thought wire gauge was strictly related only to the amperage which is strictly related to the loads. And my last question is, should I consider getting a stabilizer? I appreciate again every reply, I apologize for not being specific on the fact that the laser printer wasn't connected to the UPS. I shall be waiting for more, regards.

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"Could this still be a problem with my circuits length? or wire gauge?"

Absolutely! A longer run requires a larger gauge of wire to keep the same voltage drop. I don't remember whether it was you or the OP that mentioned a run of 300 feet. 300 feet is a VERY long run for a 120V circuit. That's about 6 times as far as a more reasonable 50-foot run. In order to keep the same voltage drop, the wire for the 300 foot run needs to have a cross-sectional area 6 times as large as the wire for the 50 foot run. If a size 12 wire is appropriate for the 50-foot run, the 300 foot run would require size 4 wire to keep the same voltage drop.

There are many wire size calculators available online. Choose a couple of them, and enter your numbers. If the two agree reasonably, then they're probably right.

The first one I came across, that was on a secure site, is https://www.southwire.com/calculator-vdrop Disclaimer: I am not endorsing this site, and have not tried it.

That's a very interesting reply Moe, you see, I have two cases, with practically the same exact charasteristics. In one, the transformer is buzzing, let's say around 300 feet away from the connections. It's not the "High" voltage transformer though, the system in this building enters with 277/480 and has a step down transformer to 120/208, three phases since it's a commercial building. The receptacles in the office where I'm having this issue are 20amp receptacles, and the only device affected apparantly is that UPS. In the other case, the panel is 40 or 50 feet away, it's a normal 120/208v system, and the receptacles are 20amp. I haven't tried tripping the breakers but I see where you're going. Could this be a problem with inductive power?

Hi naviero1, when a transformercoil is added to a circuit, it also adds resistance to the circuit, and the more resistance, the less "stiffness" i. e. bigger voltage drops, when loads are applied. What amperage is the transformer rated for? The smaller, or closer to max output, the chances for iron-saturation in the transformer is bigger.

You mentioned "commercial building", that means the cables are running inside the building, and is exposed to heat, running in ducts with other cables. When temps rise, resistance rises too, both for copper and aluminium. Las Vegas, thats in the desert, and thats hot!

Also, a rise in the transformer temperature adds resistance.

On top of that, 300 ft of wire is a lot, even though the gauge is correct for the amperage. Where I'm located, thats the limit for smaller, "end-user" cables. If I encounter distances like that, I calculate the wire resistance, and may end up with recommending 2-3 bigger gauge number, than the amperage require. If the installation includes somekind of motor(a fridge), the initial current may be full load times 10! If you then allow only 2% voltage drop, the cables get quite thick.

All power in the real world is inductive, because it goes in and out of a transformer several times from the power plant to the consuming equipment. Switched-mode power supplies, as seen in most modern computers, provides a capacitive load. You may end up with a powerfactor, when all the equipment is counted in, that is too far from 1.

The UPS switch-over threshold is also something to consider. Maybe it can be adjusted to cope with the voltage-drops? Ask the manufacturer.

Overall, it is a complex scenario with a lot of potential faults, and it may be difficult finding the real problem, also without costing the customer too much.

I hope you find the right solution. Thanks for the GA!

Regards, moe

Read the post by MJB, he has it nailed. The fuser is the problem. Somewhere in the literature that came with the printer it says the unit should be on its own separate 20 amp circuit. If you don't have one available call an electrician. That will solve the problem. I have even seen tags attached at the plug end of laser printer's power cord that say the unit needs it own circuit. Somewhere I have the time vs current characteristics for a standard (I believe xerox) fuser, if I can find them I will send them to you or post them here.

That would be very useful thanks

Naviero1,

I suspect that the offending laser printer and the UPS are served from the same phase and share a common neutral conductor back to the panel.

A shared neutral is legal per NEC 215.4, but it's a bad idea when the feeders can run more than about 30% of rated load, particularly if a couple of heavy loads (UPS, laser printer) are on the same phase. If the loads are properly balanced, the neutral current is small. However, if two large loads are fed from the same phase, the neutral current will be the total imbalance, possibly as much as sum of the two load currents. For example, if Load A is running 12A, and cycling Load B idles at 2A (on the same phase), the current on a shared neutral would be 14A => no problem. Now Load B cycles to full draw and current spikes to 13A, making the shared neutral 25A. Each 20A breaker is still well within its capacity (12A & 13A), but the AWG #12 neutral is 35% overloaded and will cause excessive voltage drop every time Load B cycles on. The neutral has no breaker, so no indication of the overcurrent.

To prevent problems like this, IT and other non-linear loads should have a dedicated, full-size neutral for each circuit breaker. If this is a standard commercial design, there is conduit from the panel to a junction box, then MC to individual receptacles and other loads. If the UPS and the printer neutrals are tied together in the JB, with a single conductor back to the panel, pull in another neutral from the panel to the JB and connect it separately to the printer neutral. You should do the same for any other IT loads (workstations, printers, UPS, etc.) until each breaker has its own associated neutral conductor.

Before making any changes, you can verify the problem by using a clamp-on ammeter on the home run back to the panel to measure neutral current when the voltage drop occurs.

GA

There may some short circuit inside the printer otherwise it won't happen, Printers recure very few voltages for running, If you still persisting this issue better take help from canon customer service

Welcome to CR4!

Unfortunately, you are wrong. As has been described in several of the above posts, the heaters that melt the toner onto the paper in laser (not inkjet) printers do require significant current cycling on and off at their design voltage, and the OP has 3 of them running at once.

Further, this was 8 years ago. If the OP hadn't solved the problem in all that time, then he wouldn't be around CR4 to get more help.

Every print job causes a major voltage drop, causing lights on the circuit to flicker and, if it's plugged into the same circuit as her PC, tripping the backup power supply. ... Cursory reading suggests that all lasers cause this big voltage drop.

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If I pay close attention, I can see a slight flicker due to the heater on my laser printer, and I've seen the same on other people's laser printers and copiers, but it's never caused a problem. If there is enough voltage drop to trigger an Uninterruptible Power Supply, then there is a problem with the circuit supplying that power.

The problem could be an oxidized contact anywhere from the panel circuit breaker to the sockets where the computer and printer are plugged in. A fairly likely culprit would be a cheap or old multiple power strip/surge protector. Laser printers should never be used on extension cords; if they must be used, such cords should be heavy duty, high quality, and clean.

I have even seen tags attached at the plug end of laser printer's power cord that say the unit needs it own circuit. Somewhere I have the time vs current characteristics for a standard (I believe xerox) fuser, if I can find them I will send them to you or post them.

If the UPS and the printer neutrals are tied together in the JB, with a single conductor back to the panel, pull in another neutral from the panel to the JB and connect it separately to the printer neutral. You should do the same for any other IT loads (workstations, printers, UPS, etc.) until each breaker has its own associated neutral conductor.

Read the post by MJB, he has it nailed. The fuser is the problem. Somewhere in the literature that came with the printer it says the unit should be on its own separate 20 amp circuit. If you don't have one available, call an electrician. That will solve the problem. I have even seen tags attached at the plug end of laser printer's power cord that say the unit needs its own circuit. Somewhere I have the time vs current characteristics for a standard (I believe xerox) fuser; if I can find them I will send them to you or post them here.

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