Question for you electrical engineers out there re: voltage drops effecting laser power

HI Guys,

I live/work in a developing nation (Thailand), where many things are not quite as stable as they are in the western world. Like access to toilet paper during a pandemic. But that’s a subject for another longer rant :smiley:

We are currently experiencing a bit of a voltage issue at our factory. The supply here is announced at 230V 50Hz, and until about a week ago we had never monitored what was actually coming in to the building… we had no need to since everything was working properly (we thought). We did have occasional issues that in hindsight may be related… but I do not want to jump off on any tangents just yet. The issue is that we recently purchased a new monster of a compressor (4350 watt) to run the air for our multiple lasers, and it has a voltage monitor on it. Coincidentally? the day it was hooked up (before being powered up!) our other hardware started lagging off… the other compressor was running slow and our big (1325) laser was not fully cutting like it should. The voltage on the new compressor showed 177 volts at that point, and that compressor would not turn on, since it has a low voltage alarm that prevented it (and very nicely told us so!). The power company came out and twiddled some knobs down the road (they said there was a loose fuse), and the power went up to 220v and things worked for a minute. Today I come in and we are back to 204v with a massive drop as soon as I turn fans and compressors on.

So… that particular issue aside as I have the local power company coming out to take a look at that, my question is more of a theory one for you out there that know the ins and outs of the high voltage power supply inside the laser itself. And that is: How much will a voltage drop from 220 (average in-shop voltage) to 200 or even 190 affect the output of the laser tube? Will it be a significant drop or perhaps none at all due to all the step ups needed before power hits the tube? And lastly is there anything I can do to mitigate that in any way? Such as a strategically placed battery backup or something?

Looking for ideas here on how to deal with this and still be able to keep production running…



I’m not an electrical engineer, but would have thought a drop in supply volts, once multiplied to the high power of the tube would be magnified not decreased. I’m sure there is a level of drop off built in before it makes a difference, but cannot tell you what that is.

Running big fans and compressors will of course drain the available supply and if that is not stable then you will risk at some point the laser either stopping working of having power related issues.

maybe run the compressors on a generator? Or4 ask the power compant to supply a 2nd power line and split the load of all the items.

I goto Thailand often, my wife is Thai and we have a house hear Bangkok, judging by the 100s of power lines hanging off the poles 1 more to your place won’t be noticed haha, Oh and in the UK we to had everyone buying up all the toilet paper like selfish idiots at the start of the pandemic…same happened with petrol a couple of months ago…99% media created panic!

Hope you solve your issues, you must have a lot of laser machines to need a compressor that big!

All the best LA

They (the power company) solved the immediate issue today by changing out one of the lines that run to my shop. Apparently it had corroded, and so far so good… the voltage drop now when the big compressor kicks on (only once every 20 minutes or so for 30 seconds thank goodness) is only about 8V. So its much better.

BUT… I am doing my first production cut now since they did that and I can see a marked difference in the laser power. Whereas before 80% of the product we cut would drop thru to the laser bin on its own, at least 20% would not and would need to be shaken/touched or even in some cases forced to release from the sheet (splinters would catch etc), but now everything is falling thru… so I may be running the laser too slow for this newly upgraded voltage, or perhaps at a higher power than necessary. Will have to run my speed/power grids again and see whats what.

And as to the TP comment, I was kinda joking. Since you come to Thailand often I am sure you are aware that there are alternatives here lol… I am a big fan of the “bum gun”. For those not yet initiated, that device is a modern miracle. Its essentially a water spray gun attached to every toilet in Thailand… and once you learn how to use it, your use of TP will just fade away to nothing. I had lived here for over 10 years before a bout of stomach issues and a lack of TP in the house forced me to use one for the first time… now we just don’t even buy the stuff anymore. But if you need to go and the water to your house is out… well, your going to have a bad day haha.

Back to the laser, things are working much better now at a fairly stable 225V, so will see how things go… but I am still curious about the physics behind the voltage step-ups

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