How to minimize voltage drop caused by heavy machine?

[gfretwell]

If this is a wall wart supply, the capacitor trick is easy. Get a male cord and female connector the right size and just plug the capacitor in across the line.

[Tomsic]

Another thought, assuming the UPS unit or units are working properly, is to cut the power to the UPS while the scanner operates, let the UPS carry the load for a few seconds, and switch the power back on when the scanner is done. That way the saw, whatever it's doing, can't affect anything on the plug strip.

TK

[Art Todesco]

If it's a DC output wall wart. Some are AC.

[yyy378]

The electric system in this country is notorious. Every house that can afford a generator has one. When there is a power outage, you hear generators humming everywhere. Some people have stabilizer also because the power from the grid may be only 180 or 190 V.

I have a 30 KVA 3 phase stabilizer. Not sure if it will help or can be used in a single phase environment.

My multimeter is also analogue. I still have to rely on the needle to tell the voltage. What I said about 50V drop is just my guess. It is difficult to tell the actual number from a small needle pointer.

The saw is 2000W, 8.8A. The wire feeding the saw is slightly less than

13 gauge (2.5 mm2 cross section).

The switching device for the generator is a simple double knife switch. It needs to be manually switched between grid and generator.

[bob haller]

Back in the 1970s I worked as coiper service tech. Our buildings wiring was ancient and undersized. copies either came out too light or way too dark depending on the line volatege at the time of the copiers use

my work around was to set the exposure lamp as brite as possible, then the key operator could use a high wattage dimmer to darken the copies as needed......

it worked well for a couple years till the building was demolished for a highway project

[Pico Rico]

then what happened?

[larrymoencurly]

Is it the voltage drop, or is it the line noise accompanied by the voltage drop? Because if it's just line noise you may be able to fix the problem by plugging the scanner into a surge protector containing a line filter made of both inductors and capacitors. Many surge protectors lack one, as do even some backup power supplies. For example, I had a cheap 350VA Belkin backup with no such filter in it, and the computer would freeze or reboot when a laser printer plugged into the same AC outlet was turned on, but the computer always ran fine when I instead plugged it into an old APC backup. Or maybe you just need to try a different AC adapter for the scanner (be sure it puts out the same voltage and at least as much current and that its plug is of the correct polarity) because some of those adapters contain better line filters than others do. If none of that helps, try plugging the saw into a different AC outlet through a super-heavy extension cord made of #10 or #12 wire.

[yyy378]

I just measured the voltage with a multimeter. The voltage is 210 V. Once the saw starts, the voltage drops to around 185V before coming back to 205 till the saw stops. Then, the voltage goes up to 210.

[gregz]

Best.

I say again, use an on-line ups. It outputs near sine wave. Input power never sees the output. Sounds like a similar price to a ferro xfmr.

And NO, not two ups in series.

How much does scanner cost ?

Greg

[yyy378]

I just measured the voltage with a multimeter. The voltage is 210 V. Once the saw starts, it drops for a split of a second to around 185 V before coming back to 205 V till the saw stops. Then, the voltage goes up to 210V.

I also measure the voltage at the service entrance. It is 214~215 v. There is also a 5V drop when the saw is running.

[Jerry.Tan]

I saw you post this in a rely to my last message. I did not know you're outside the USA, which means I am not sure what you really have for power, or if the power company will help you. However, that is still a huge voltage drop and not normal. You said the saw is 2000W. That's not all that large and should not becausing such a drop. Some wiring, maybe the entrance cables are too small...... I dont know what else to say!

But here's a thought. Get a 12V Deep Cycle battery and an inverter to convert to 120V AC. Plug the scanner into the inverter connected to the battery. Then get a battery charger, probably 5 to 10 amp. Charger, but make sure it's a charger with "overcharge prevention" (shuts off when the battery is charged). Connect the charger from an outlet to the battery. PROBLEM SOLVED. You're running the scanner off the battery! (Of course make sure the inverter is big enough for the scanner, which I doubt uses very much power).

[thekmanrocks]

yyy378:

My biggest takeaway from all the suggestions here is to get either the saw or the scanner off the same circuit as the other. If there are spare circuits in your breaker, have the saw moved to its own.

Simplistic I know, but that's how I think.

[trader_4]

5 volt drop at the service due to an 8 amp load doesn't sound good..... IDK what the service rating is, but extrapolating that, if the service was rated at 100A and you pulled that, you'd have ~60V drop.

[trader_4]

Did you see the recent post where he reported that the saw, when running, pulls 8A and that results in a steady 5V drop measured at the *service*?

[yyy378]

I have tried it.

The entrance cable feeds two breaker panels which are wired in parallel. I have moved the saw from one panel to the other with no noticeable difference.

[philo]

Just though of something I did once and it worked.

I put a ferroresonant line conditioner transformer between a cheap UPS and the load and it worked fine.

[yyy378]

2000 w is not much. I just remember that the electric meter is rated 10,000 W. Maybe in this case, 2000 W is not that small.

[trader_4]

Doh! That's about a 40A service? Even so, if the conductors are properly sized and everything is in proper order, a 2000W load shouldn't drop the service voltage 5V.

[rbowman]

What's the service, a hamster wheel? Or a breaker box fed by 100 feet of cheap extension cord?

[trader_4]

Did you see the next recent post, where he reported that the meter is rated 10KW? Not exactly a hamster wheel, but it sounds like 40A. Given that he says the 8A motor load drops it by 5V, the 100ft of cheap extension cord, or cheap something, sounds possible.