Receptacle Voltages?

[Cody]

Hey everybody, I have a general question that I've had trouble finding an answer for. How much voltage is too high to have at the wall receptacle for amps, pedals etc.? Somebody told me that the voltages in my receptacles were too high at 126-127 volts AC. I thought most electronics had power converters that change the voltage to DC and the proper amounts, I guess there could be an excessive point but what would that be?

I'd really appreciate any info cause i'd hate to damage my equipment.

[Chuck H]

"Somebody" is right. And wrong. Excessive wall voltages can be a problem with some amps. Some devices DO have regulators that correct operating voltages. Most tube amps DO NOT. For example, a vintage amp designed with a 110V primary that has a 4X step-up at the secondary will now have an 68 volts of HV. If the amp was already pushing the limits on the stock circuit, like a pair of el84's at 340Vp in class A, you now have 408Vp idling at over 100% dissapation. You'll probably blow something up. There are also some power transformers that fudge high on things like tube filament taps. If the PT has a 115V primary and is designed for 6.8V on the filament tap you'll get about 7.5V on the tube filaments. That's over the max tolerance for this circuit and may cause premature tube failure. But in general, most devices designed for 120V will be fine with the extra 7V on the mains side.

If your using vintage gear this would be a good subject to learn a little about. If your using modern gear don't worry about it.

P.S. Not sure why, but wall voltages have been going up and up for a long time. Some PT manufacturers now offer 125V primaries even though 120V at the receptical is the (much ignored) standard. And, FWIW, 127VAC at the receptical isn't uncommon. It probably fluctuates during the day.

[Cody]

Well that makes me feel better, I only use modern equipment. I checked the voltage at the wall throughout the day and it seems to stay at 126-127VAC. Thanks for your input

[J M Fahey]

Wall voltage has been creeping up from the 40's on.
Just check old Fender schematics and they gradually showed 110/112/115/117/120V
Now it's 127V on new households.

[Chuck H]

I've seen new condo complexes powered through giant cyclic regulation. From what I understand, the principals are like the FET regulators used in variable speed power tools. Which messes with the actual Hz! people who live in these places do have problems with noise. The voltages are are a nice steady 120VAC though!

[soundguruman]

I've seen new condo complexes powered through giant cyclic regulation. From what I understand, the principals are like the FET regulators used in variable speed power tools. Which messes with the actual Hz! people who live in these places do have problems with noise. The voltages are are a nice steady 120VAC though!

The reason is that commercial power companies raised the transmission voltage, to avoid installing thicker wires, to serve more customers. It's a cost cutting measure.
The higher the voltage is, the thinner the wire can be.
In CA. they started using 1,000,000 DC through the transmission lines, and converting it back to AC at the end, because somehow it saved them money. Although we no longer have pure sine wave power, but stepped sine wave, like an inverter.

[J M Fahey]

1 MV DC long distance lines?
Interesting. Care to share any link showing that?

[soundguruman]

1 MV DC long distance lines?
Interesting. Care to share any link showing that?

Believe it or not forum bully,
All information is not posted on the internet.
Why don't you call PG&E, and ask them yourself?
Since it's "so" important that you attack me, and prove how smart you are.

[J M Fahey]

A 1 Mega Volt transmission line, which by definition feeds hundreds of thousands people, surely is not "hidden".
Whether it's DC or AC.
It's *big* news ... if it exists.
Again, care to provide a link?
Even if a page of PG&E

[km6xz]

Juan, it is not hidden at all, a middle level system of +500kv and -500kv DC transmission lines plus an incredible grounding system that at the southern California terminal end, uses the Pacific Ocean as the ground return is just one example.

But there are many systems in operation all over the world that are bigger. It was a system developed in the 1930s by the Swedish electric company. President Kennedy authorized the project to convert a number of major urban regions to DC long distance transmission in 1960. They used mercury vapor tubes for the inverters back then but about the 1980s switched to optical triggers thyristors and IGBT...big ones. But the first DC systems were in Sweden and northern Europe and the first large system was in the USSR opened in 1951. China and Brazil both have has a 6GW!! DC systems and the longest is 2500km in Brazil. The highest static tension is about 600kv per line, or 1,200,000 volts between the lines used in several systems.
Most run differential with two exposed steel core aluminium cable or split referenced to their ground system, which lowers the tension to 500-600kv but doubles current.
If you live in California, Northern Europe, any island or in Siberia or China, there is a good chance your electricity is coming from a high voltage DC transmission system.
Right off the bat, without changing cables, a DC system can handle 130% higher current since it has higher RMS value than the same peak voltage AC system. DC is particularly good for submarine systems because of the lack of cable capacitance that AC systems have to deal with. It is used in inter-ties between different distribution networks while keeping isolation between them, reducing the chances of cascading blackouts, or worries about synchronizing between different AC system phase along a long transmission route. They even supply current to systems using different line frequencies, 50 hz and 60 hz countries can be fed with the same long range transmission system.

[soundguruman]

I first learned about the 1M volt DC system from Professor Bret Allen at Cuesta College.
He was a Senior engineer for PG&E for many years.
You are welcome to call him:
805 546 3917 ballen@cuesta.edu
Mainly we were engaged in a conversation about how solid state devices could be used to create a stepped sine wave, from DC.
It turns out that it is more efficient to run DC the transmission lines and convert it to a step sine wave at the receiver end.
As the stepped wave passes through more and more isolation step down transformers, the edges are rounded off,
and it looks like a regular sine wave at the end user. The steps are basically choked out by the inductive opposition to a change in current.

And- it's not hidden, I never said it was. It's in plain view for all to see.
For some reason they save money on the wire by doing this, and it works out to be more cost efficient.
Aluminum wire, well there's a lot of loss there. But I think we're basically stuck with it.

Amazingly, I was amazed by this- between the commercial power plant and the end user,
63% of the energy generated is lost in the wiring, which is aluminum.
And so, they keep looking for ways to improve that, even slightly.
AND you can see now how inefficient commercial power really is.

This, by the way, is why electric cars are really much less efficient than the manufacturers are claiming.
If you calculate the losses in the wiring, your MPG is falling fast.
These plants are burning oil and coal to generate...the losses in the wire are huge, and so you are actually
just moving the source of pollution from the car tailpipe to the power plant.
And the pollution turns out to be more, not less as claimed.
And so, there is no such thing as an emission free vehicle, although the manufactures want you to think so.

On the other hand, if we generate from wind, solar, geothermal, hydroelectric, etc...the situation looks much better.
(don't talk to me about nuclear, it's EVIL)
AND if the energy is produced at the point of usage, we have eliminated all those losses from the long wires.

And so, there may be hope for us after all, although in the USA, only about 3% of our energy comes from alternative sources.
70% from burning coal, etc...

Here's something:
http://en.wikipedia.org/wiki/Pacific_DC_Intertie
I wonder if Mercury Arc Rectifiers would be good for a guitar amp?

And yes it is FOUR 500KV lines, which means that if it is measured between any two lines, you have 1,000,000 volts DC.
so the 1M volt figure is accurate.

[soundguruman]

Juan, it is not hidden at all, a middle level system of +500kv and -500kv DC transmission lines plus an incredible grounding system that at the southern California terminal end, uses the Pacific Ocean as the ground return is just one example.

But there are many systems in operation all over the world that are bigger. It was a system developed in the 1930s by the Swedish electric company. President Kennedy authorized the project to convert a number of major urban regions to DC long distance transmission in 1960. They used mercury vapor tubes for the inverters back then but about the 1980s switched to optical triggers thyristors and IGBT...big ones. But the first DC systems were in Sweden and northern Europe and the first large system was in the USSR opened in 1951. China and Brazil both have has a 6GW!! DC systems and the longest is 2500km in Brazil. The highest static tension is about 600kv per line, or 1,200,000 volts between the lines used in several systems.
Most run differential with two exposed steel core aluminium cable or split referenced to their ground system, which lowers the tension to 500-600kv but doubles current.
If you live in California, Northern Europe, any island or in Siberia or China, there is a good chance your electricity is coming from a high voltage DC transmission system.
Right off the bat, without changing cables, a DC system can handle 130% higher current since it has higher RMS value than the same peak voltage AC system. DC is particularly good for submarine systems because of the lack of cable capacitance that AC systems have to deal with. It is used in inter-ties between different distribution networks while keeping isolation between them, reducing the chances of cascading blackouts, or worries about synchronizing between different AC system phase along a long transmission route. They even supply current to systems using different line frequencies, 50 hz and 60 hz countries can be fed with the same long range transmission system.

He should be working on interstellar travel,
not guitar amps.
What a waste of talent.

[J M Fahey]

SGM , thanks for posting a link.
If you had simply done it when asked for, you could have saved about 55 to 60 lines of useless text.
Was it *so* difficult?

KM6XZ, I was also amazed that SGM could not offer proof, beyond the ridiculous idea of *phoning* somebody.
In fact I guess he googled the Wiki article *after* you quoted it.
Just sayin

[olddawg]

I like modern nuclear power. Clean and efficient if implemented correctly.

[Chuck H]

But SGM did, apparently, know about it prior to the need of offering proof. That IS significant IMHO.