Studio voltage regulation

[Bo.b]

Hi,

I live on an island where the power grid has been struggling with overdevelopment and under-investment… as a result the grid has been really struggling. It gets really hot in summer and the distribution network has really struggled to keep up, high voltage cables running below roads burn up and other fun stuff.

As a result, I’ve been keeping an eye on the voltage I’m seeing at my outlets and during really bad times I’ve seen some crazy swings (118v to 308v!!) when our nominal spec is 230v +\-10%. This was on a particularly bad day where I think there was some kind of a major fault somewhere nearby, but circuit breakers didn’t trip and I only noticed as a fan I was running went from super slow to extremely fast. Needless to say I disconnected the house from the mains and sat it out.

I rarely see the voltage drop below 243v or so… I guess they’re running the grid at a higher voltage to take some pressure off the distribution system or something like that.. voltages regularly hit 250v and the “over-under” cutoff box I’ve had installed just after my meter cuts off power every few days when it hits 255v..

we’ve never really paid attention to voltage specs on any equipment imported, so stuff around the house can have anything from 220v 230v or 240v written on the back..

Considering most specs are +\-10% then:

220v = 198v - 242v
230v = 207v - 253v
240v = 216v - 262v

I’m running some equipment that could be very expensive to repair, so I feel it is wise to try to deal with this voltage, and I guess try to get it stabilised to the nominal 230v (though with the supply seemingly coming in around 240+v I wonder whether it is wise to do this)

I’m running a newer console that is rated 100-240v +\-10% but if the psu’s get cooked I’m looking at many thousands in replacements, so it concerns me.

I’ve also got a fair amount of rack mounted gear

I run a few vintage amps from the US that are rated for 117v, I use cheapo step down transformers for this(though would like a more sophisticated solution in the future)

Otherwise, I often have up to three split air-conditioners running some days, so there’s quite a load from these to consider

I’ve unfortunately got the whole studio running on a single electricity phase, as though three-phase supply is available, rewiring the whole facility would be a massive job.

I’m trying to figure out how best to proceed here.

Do I get a few smaller and more affordable voltage stabilisers? Perhaps a 5-10kva one for the console that is spec’d as 1.54kW with an “over voltage range” (peak inrush current) listed at 14A,

And maybe a couple of 1kva ones to run my outboard rack, and another one or two to float around and be connected before the step down transformer for the American amps, etc..

I’m not sure “voltage stabilisers” is the correct term for what I’m looking at. We’re talking the boxes with the large toroidal inside..

The smaller ones(1kva) are available locally for about €50 each, whereas a big 8kva goes for about €250.

Is this a sensible solution for my situation? Or do I need to go for something a lot more expensive but unfortunately more suitable for the application?

Do I go for a big one and have the whole facility run off it? Our single phase supply is fused for 40A

Should I be concerned from an audio perspective with any of this? Might I introduce noise to the system?

I remember working in a studio years ago in London that had a pretty massive transformer doing this(as it was explained to me) locked away in a back room and it make a very loud noise (a buzz) all the time. Is this to be expected? Should I look to install this in a box outside? Would 40°C(104°f) summer temperatures be a concern?

Any advice would be very appreciated. I’ve spoken to a number of domestic electricians locally and they don’t really have much insight to offer.

Sorry for the essay… thanks a bunch for taking the time to read all this

Bob

 

[daschnoz]

With voltage swings being that extreme, my only recommendation is something on-site that will generate clean and stable power.

A pure sine wave inverter generator would likely be the easiest, but you will have the recurring fuel cost to deal with. It also brings noise, which may or may not be a problem depending on where the generator is located relative to the studio. That all night session may piss off the neighbors too (if they're right on top of you).

You could also go with an "off-grid" solution.

• pure sine wave inverter
• battery bank with enough capacity to run full load for a couple of hours
• battery charger (power supply) that can handle the extreme input voltage swings and deliver stable output

Your studio power comes from the inverter. The battery charger provides what it can to the inverter for "right now" power (if you have a 500W supply and you're pulling only 200W). The batteries provide the bulk of the power under full load conditions, then recharge at low/no load. Add some solar panels if the budget allows, or at least consider them in the initial design so they can be easily added in the future.

Whatever you're using to power the inverter (gas or battery), make sure to oversize the inverter, as most of your loads will be inductive (power transformers).

Heat kills electronics, so cooling is most definitely a consideration. The good thing is that this can run from your power utility, so it's not adding a load to your on-site power generation.

If you go the battery route and want to power everything from the battery bank, try to keep any auxiliary stuff running on the DC battery voltage (example: cooling fans). It's more efficient since you're not burning power in the inverter to convert DC into AC.

 

[Bo.b]

Thanks for this. I’ve considered this in the past but we’re talking 10’s of thousands of capital outlay. This would be a significant hit and would put of some pretty important purchases that the operation is screaming out for(like a decent baby grand..)

Perhaps I was unclear, voltage tends to be moderately stable at around 240-255v, though often fluctuates between these figures relatively frequently.

I have an “over-under” box after my electricity meter that cuts off power when the parameters I’ve set are exceeded. This happens infrequently (perhaps every couple of weeks) and while not ideal, with a UPS on the computer I’d be able to handle the studio “turning off” when things get wild… I can blame the grid, and it doesn’t tend to last long…

 

[My3gger]

Do you have noise on unbalanced lines? Where i live voltage regularly fluctuates between 225-240V, even more during the summer because the last time they added capacity to the grid was probably in Yugoslavia under Tito. These troubles are heard as pretty loud noise in unbalanced lines, other lines where at least input is balanced are fine.

 

[Bo.b]

I’ve got very little that is unbalanced around here, so I’m not too sure how to answer you. I have my suspicions that guitar amps are noisier than they should be, and I’m just used to it, but I don’t think I have a single connection on my patchbay that is actually unbalanced(!)

 

[daschnoz]

Your measured 118-308 has me concerned when the line voltage is supposed to be 240. Could those could be spikes as your AC (or the neighbor's) kicks on/off?? If that's the case, it sounds to me like you need a good spike arrestor on the line. 240-255 isn't bad at all. I see 115-125 (North America, nominal 120) regularly, and it's not an issue.

 

[Bo.b]

This was a one-off during the peak trouble/hot season when a lot of the country was dealing with regular power outages. They ended up shipping in a load of medium sized gennies and actually parked them all over the place hooked up to substations. I guess to distribute the load rather than have everything coming from the one power station alone

It sounds nuts just writing it down.. awfully 21st century of us…


. The guys at the electrical supply store I was chatting to said they’d never heard of such a swing and they suspected there “probably was a street cable that caught fire nearby, with the neutral shorted or something”

As I’d said, practically always see 240-255v at the outlet. Our nominal supply should be 230v +/-10%

I have an “over-under” that cuts off anything outside 220-255v as I’ve set it. I want to also add a surge protector at the fuse box to help cover any crazy stuff like lightning hits etc…