Just a thought experiment really, but if there is a way to do it, I'll consider it.
I have a good but cheap 220v Plasma cutter. It keeps indicating over-volt protection and not functioning. The owner's manual says that it goes into protection mode with anything above 246v. Testing my breaker shows 249v. Tesing the outlet shows 248.8v. The owner's manual also says that there is a pot on the circuit board that can adjust the overvolt protection, but I'm finding no such pot.
Next thing I did was to make a 50-foot extension cord to hopefully drop the voltage, but it isn't enough, and with 10/3 SJO costing $4/ft, it might get pretty expensive to get the voltage drop I need. After 50 feet it still shows 247.5v. Not to mention, that's a terrible idea to intentionally sabotage by using too much cord.
I have a feeling the issue is that we're the first service after the transformers and they have to keep it a little hot so the next few services don't drop too low.
The appliance is 15 years old, so customer service doesn't exist.
The transformers for the building are on top of a pole, and I'm not going to be playing with 7200v and turning myself into a crouton.
Is there something I can do to drop a few volts? Can the power company adjust the transformers? Can I put something inline to tame it down?
You need a buck/boost transformer. Like this
there are used ones on marketplace for cheaper.
I assume they make them in higher current versions? Not sure if I need it with this plasma torch, but the two 240v circuits in the shop are 20A and 60A. Usually the 60A runs the powdercoating oven which doesn't care about over volting, but it would just be nice to have the capacity.
A buck transformer is what you're after.
is 249 volts within spec for household voltage? Might be worth asking your power company in case one of their transformers needs adjusting.
codrus (Forum Supporter) said:
is 249 volts within spec for household voltage? Might be worth asking your power company in case one of their transformers needs adjusting.
240vac +/- 5% is the nominal service voltage in the US, so 249 is within that range.
Having said that, the utility transformer should have a couple different taps where the voltage provided can be slightly adjusted. The serving utility *may* be willing to change it, but the customer has to make a request, then the utility comes out and puts a data recorder on the line for a while before deciding if they'll make any adjustments. More often than not, unless the voltage is way out of spec they aren't going to do anything.
Also worth considering is that one transformer up on the utility pole likely serves several different customers, so any changes will affect them as well.
DO NOT DO THIS
I bet you'd get some decent voltage drop with 18AWG. Plus it would heat your shop up too!
/DO NOT DO THIS
Tom Suddard said:
DO NOT DO THIS
I bet you'd get some decent voltage drop with 18AWG. Plus it would heat your shop up too!
/DO NOT DO THIS
Yeah, but it would smell funny for weeks after the fire department came.
You could always tap a couple of incandescent light bulbs onto the line. That should drop the voltage supplied a little bit. The wattage, too, of course :) They'll just be a bright resistor..
I had this problem when I wired up my phase converter for the CNC machine.. It was designed around 208V which was more common in the states pre 2000 (it's a 1998). They allow +-10%, so that's 228.8, but my voltage at the house on the high leg of the phase converter was almost 248! So yeah, the proper fix was a transformer.
There are more than likely multiple taps on the utility transformers that will provide a range of voltage. It could be that 249V is as close to 240 as they could get, or maybe they set it a little high deliberately, as you said, to maintain nominal voltage to other customers down the line.
It is worth contacting the utility and letting them know you are seeing high voltage. I think they're allowed a 10% variance from nominal 240V, but maybe, if you are lucky, they will actually want to adjust it.
Wonko - 208V 3-phase is still very common. It is the default distribution for everything other than residential. Lots of non-residential equipment will also call for 208V single phase rather than the 240 we use in our homes.
We also do a lot of light quasi-industrial spaces that are typically 3-phase throughout with a single 120/240V 1-phase transformer for welders, saws, etc.. For some reason (possibly overlap with the hobbyist world) those often need single phase 240V power.
Tom Suddard said:
DO NOT DO THIS
I bet you'd get some decent voltage drop with 18AWG. Plus it would heat your shop up too!
/DO NOT DO THIS
Now you've done it!
Many, many years ago, in a college dormitory somewhere in the continental US, I may have had some level of involvement in a science experiment that took place in a designated study hall in the dorm. My roommate's 12" woofer in one of his KLH speakers suffered a broken cone (no idea how that happened. Excessive volume, perhaps?) The driver, and the resistance wire element from a broken hot-pot were used in the experiment. The wire was removed from the appliance and one end was jabbed into an A/C wall outlet. The other end was attached to one terminal on the broken woofer. A short piece of wire from the other speaker terminal to the other side of the A/C wall outlet completed the circuit.
I have no idea what voltage was seen by the voice coil of the woofer, but that thing made quite a racket, a monstrous 60-Hertz hum, if you will, right up until the dangling coil of resistance wire found a way to cross itself and short-circuit, omitting most of the length of wire and breaking the circuit in a shower of sparks. Simultaneously, the voice coil, upon receiving a surge of higher voltage, chose to stick at one end of its limit of travel.
And so the science experiment ended. We really should have taken voltage readings and done a proper write-up, but we may have been drunk at the time.
So, yeah. A length of Nichrome wire should do the trick. You'll have to tinker with the length.
j/k
In reply to grover :
I strongly suspect that the wire in most toasters is of insufficient gauge to carry the current required to operate a plasma cutter, but yeah.
1988RedT2 said:
In reply to grover :
I strongly suspect that the wire in most toasters is of insufficient gauge to carry the current required to operate a plasma cutter, but yeah.
Okay, 2-3 toasters in parallel then.
In reply to 1988RedT2 :
So, 60hz, somewhere between low B and B flat. That note must be permanently embedded into your brains.
https://muted.io/note-frequencies/ : Note Frequency Chart (Pitch to Note)
In reply to Tom Suddard :
I'm thinking three toasters in parallel and a baseboard heater.
"Local Gearhead Burns Down 99-Year-Old Theater."
Just predicting tomorrow's headline
First thing you do is roundup an old Coherent Radiation argon laser power supply from the 1970´s... (boost-buck)
