If they have parallel kits you can do that. If not they will not have synchronized phase, which can cause large potential between them which can be dangerous and it is not recommended if you care about equipment and peoples safety.
2x3500 inverters from a decent budget brand like Champion would cost more than the UPS and a basic diesel generator together it seems like, and would still not provide enough current. Perhaps 2x Honda EU70is would be enough, but that will cost over €10k.
I have no idea where you are, I feel your concept and ideas are a kludge.
I was told to install a 125 kVA generator when the biggest motor was 25 HP (18.75 kW) in the system, it has something to do with starting torque.
40 kVA is a common size at cell phone sites here, so it is quite easy to find a diesel set, complete in acoustic enclosure, generally with a good quality engine, generator and PLC panel.
It is easier now to obtain a solar / wind system, without batteries in grid tied model, batteries are a very big part of the initial system,
And it would be best if you can arrange for temporary grid power at the site.
To buy a generator, service it, maintain it and so on....you need to run it half an hour every so often, change oil and so on....unless it is really needed, it is too much hassle.
Not to mention the rest of the equipment, speakers and so on...you intend to store them safe from rats and the environment for a full year as well?
You need a big facility to do that.
My advice is to look at rock show documentaries, and those for open field festivals, that will give you some idea about the way you could do things.
And don't talk about crest factor and so on, find a competent service engineer who does work in that industry, for eample off shore oil exploration, where generators have to be really reliable.
Their choice of ratings will be more realistic than that quoted by a salesman, particularly one in China.
I was told to install a 125 kVA generator when the biggest motor was 25 HP (18.75 kW) in the system, it has something to do with starting torque.
40 kVA is a common size at cell phone sites here, so it is quite easy to find a diesel set, complete in acoustic enclosure, generally with a good quality engine, generator and PLC panel.
It is easier now to obtain a solar / wind system, without batteries in grid tied model, batteries are a very big part of the initial system,
And it would be best if you can arrange for temporary grid power at the site.
To buy a generator, service it, maintain it and so on....you need to run it half an hour every so often, change oil and so on....unless it is really needed, it is too much hassle.
Not to mention the rest of the equipment, speakers and so on...you intend to store them safe from rats and the environment for a full year as well?
You need a big facility to do that.
My advice is to look at rock show documentaries, and those for open field festivals, that will give you some idea about the way you could do things.
And don't talk about crest factor and so on, find a competent service engineer who does work in that industry, for eample off shore oil exploration, where generators have to be really reliable.
Their choice of ratings will be more realistic than that quoted by a salesman, particularly one in China.
I appreciate the feedback, but would be great if you could specify what parts of the arguement is incorrect.
A motor has a very different draw than an amp, and is not point in comparing them. But typically when talking about peak capacity om a generator that is for things like motors and lights which can draw a lot of current for a short time. However that short time is usually counted in seconds, not in ms as the case with audio waveforms.
It is not hard to find a 40 KvA generator...if you have at least some €10k to spare. But renting them around the area I need is a matter of luck really.
Sure I can look how everyone else is doing it, and keep doing as I have done through the years and rent a massively oversized generator. But of I wanted to do that, then I would not need to make this post, would I?
Obviously it is not ideal to run a 40KvA generator to generate less than 5000w average.
Someone working in the oil industry is most likely clueless about audio, and would not trust them for advice really even if they know about generators. But I happen to live right next door to one of the leading companies making and renting generators specifically for large sound systems, and will check with them before I proceed with anything.
But just in speculation stage so far, and figured I check if I can get any value feedback here first.
A motor has a very different draw than an amp, and is not point in comparing them. But typically when talking about peak capacity om a generator that is for things like motors and lights which can draw a lot of current for a short time. However that short time is usually counted in seconds, not in ms as the case with audio waveforms.
It is not hard to find a 40 KvA generator...if you have at least some €10k to spare. But renting them around the area I need is a matter of luck really.
Sure I can look how everyone else is doing it, and keep doing as I have done through the years and rent a massively oversized generator. But of I wanted to do that, then I would not need to make this post, would I?
Obviously it is not ideal to run a 40KvA generator to generate less than 5000w average.
Someone working in the oil industry is most likely clueless about audio, and would not trust them for advice really even if they know about generators. But I happen to live right next door to one of the leading companies making and renting generators specifically for large sound systems, and will check with them before I proceed with anything.
But just in speculation stage so far, and figured I check if I can get any value feedback here first.
First thing you should have done...ask them, or somebody competent and local, familiar with your conditions.
As for rating, perhaps the audio term 'headroom' will give you some idea, the supply must not sag under load.
Doing it with a capacitor bank is tricky.
And a capacitor bank on the DC side of a UPS or similar is plain injudicious, I will not use the stronger term that comes to mind, but that is likely to invite the site adminstrators to discipline me.
As for rating, perhaps the audio term 'headroom' will give you some idea, the supply must not sag under load.
Doing it with a capacitor bank is tricky.
And a capacitor bank on the DC side of a UPS or similar is plain injudicious, I will not use the stronger term that comes to mind, but that is likely to invite the site adminstrators to discipline me.
I rather think about the problem properly before contracting experts, but if you hate the subject being discussed in a forum, go to an oil rig and talk to your experts
I think I defined what crest factor and headroom I think I need in original post. Was anything about my calculations incorrect, or did you not even bother reading it before jumping in with random opinions about motors, oil rigs and telestations?
Online UPS will have both capacitors on the inverter as well as using the batteries, no need to add more. If you don't even know what an online UPS is, why are you trying to give advice regarding it?
I think I defined what crest factor and headroom I think I need in original post. Was anything about my calculations incorrect, or did you not even bother reading it before jumping in with random opinions about motors, oil rigs and telestations?
Online UPS will have both capacitors on the inverter as well as using the batteries, no need to add more. If you don't even know what an online UPS is, why are you trying to give advice regarding it?
I'm going to be doing a bunch of shows on a generator this winter at a ski resort in Colorado, US. I've also done a lot of shows on little 2500W generators and off grid raves in the deserts here, and last week I even did a little tiny wedding off a 1000W inverter hooked to my pickup truck.
I've observed the same thing that prompted your post.
Namely, I've often looked at a power distro with a meter and wondered at a rather large sound system and lighting rig drawing 12A collectively across three phases.
Folks a lot more experienced than I (who are up the money chain from me, and thus make these decisions) typically just overspec stuff because the cost of failure is much larger than the cost to rent/buy equipment.
However, while I am open to the idea that they are incorrect, I have some thoughts on your proposal.
For me and the folks I work with, that generator is a very small cost compared to the show but very difficult to have backups (cause it really can't go down during a show, so like, if you need a backup you're already hosed). Given that there needs to be a generator at the event anyhow, it seems easiest to just hire the appropriate sized one, but maybe your local environment is different than mine.
Also, it seems quite plausible to me that a smaller generator plus an appropriate battery+inverters would would cost just as much as the larger generator or that would be a more common way of working. That's some lazy reasoning, but it's served me well in other places. Looking at online power supplies under the assumption that your system needs more than 20kVA, these devices seem substantially more expensive than you're indicating. It's apples and oranges, but in the US you can get a 40kW generator used (no trailer) for about the same price as a (new) 16kW online UPS depending on where you're looking. Considering that I can rent a 60kW generator set for $1100/wk spending 10 times that to own one would be a hard thing unless I was using it for many months out of a year.
One last thing I am curious about is that the supplies for all the power amps I know have quite alot of capacitance in them; though it's not consolodated in a single point in the power for the entire system, does that capactitance in the audio amp supplies make the UPS kind of redundant?
In any case support your quest to solve the issue- go get yourself an inverter and see if it works, and then let us know what you find.
I suspect that what you will find is that any inverter that you're going to put inline with the rest of your system will not be able to output sufficient current to operate your system; my experience has been that inverters often overstate how much they are able to output and for how long they are able to output that before ceasing to fuction due to thermal dissipation.
But hey, try it and let us know.
I've observed the same thing that prompted your post.
Namely, I've often looked at a power distro with a meter and wondered at a rather large sound system and lighting rig drawing 12A collectively across three phases.
Folks a lot more experienced than I (who are up the money chain from me, and thus make these decisions) typically just overspec stuff because the cost of failure is much larger than the cost to rent/buy equipment.
However, while I am open to the idea that they are incorrect, I have some thoughts on your proposal.
For me and the folks I work with, that generator is a very small cost compared to the show but very difficult to have backups (cause it really can't go down during a show, so like, if you need a backup you're already hosed). Given that there needs to be a generator at the event anyhow, it seems easiest to just hire the appropriate sized one, but maybe your local environment is different than mine.
Also, it seems quite plausible to me that a smaller generator plus an appropriate battery+inverters would would cost just as much as the larger generator or that would be a more common way of working. That's some lazy reasoning, but it's served me well in other places. Looking at online power supplies under the assumption that your system needs more than 20kVA, these devices seem substantially more expensive than you're indicating. It's apples and oranges, but in the US you can get a 40kW generator used (no trailer) for about the same price as a (new) 16kW online UPS depending on where you're looking. Considering that I can rent a 60kW generator set for $1100/wk spending 10 times that to own one would be a hard thing unless I was using it for many months out of a year.
One last thing I am curious about is that the supplies for all the power amps I know have quite alot of capacitance in them; though it's not consolodated in a single point in the power for the entire system, does that capactitance in the audio amp supplies make the UPS kind of redundant?
In any case support your quest to solve the issue- go get yourself an inverter and see if it works, and then let us know what you find.
I suspect that what you will find is that any inverter that you're going to put inline with the rest of your system will not be able to output sufficient current to operate your system; my experience has been that inverters often overstate how much they are able to output and for how long they are able to output that before ceasing to fuction due to thermal dissipation.
But hey, try it and let us know.
Some great points and food for thought johnreeve, thanks!
I'm sure renting is the easiest usually, but like I said it is tricky in this case. It cannot be booked in advance to rent it during a weekend and they prioritise the usual customers that rent them for weeks. So I just have to hope there is a 40KvA in the region, or pay some €800 for them to have one sent from another depot.
And owning a 40KvA is out of the question. If I had that money to spend on my hobby project it would be for something practical, not a monster I need a forklift or crane to move
Yes, the amplifier has capacitors that will help handle the peaks. And from what I understand, amplifiers with more and larger capacitors can handle longer and louder peaks with the same PSU.
I don't really see why one could not add more buffers earlier in the chain if the problem is that current draw from the amp exceeds what the generator can deliver at peaks. From what I understand, using an inverter generator means it can handle louder peaks thanks to the capacitors in the inverter. I just watched a video the other day with David Lee from Bassboss where he made that exact claim.
I guess current drawn by the amp will be smoothed out already by the caps, meaning that the peak durations are longer than your typical audio rate signal. Perhaps the length of the kick instead of a waveform cycle. While additional caps before the amp would lessen the voltage dip they might not be enough to hold it steady for such long durations. But, at least in theory, since the online UPS should instantly balance the load between batteries and source, as long as the batteries has a sufficient discharge current, the system should be able to keep the voltage stable.
Sure, in practice I can totally see it not working out Batteries might have to constantly charge and discharge at a quite high rate, which neither the cells nor the UPS might handle that well in the long run.
If it is true that an inverter generator can deliver more peak power, it must be possible to take the inverter part and attach that between a diesel generator and amplifier.
Even if you cannot get the full 4x peak power I speculate about, to make only the inverter part but, but a bit oversized, for a resonable cost.
Just found now a online UPS claiming 10000w, https://powerwalker.com/product/10122127/ available here in Sweden from a big tech and office supply store for €1500, so not so surprising one can buy similar units directly from factory for about half that before import tax.
I'm sure renting is the easiest usually, but like I said it is tricky in this case. It cannot be booked in advance to rent it during a weekend and they prioritise the usual customers that rent them for weeks. So I just have to hope there is a 40KvA in the region, or pay some €800 for them to have one sent from another depot.
And owning a 40KvA is out of the question. If I had that money to spend on my hobby project it would be for something practical, not a monster I need a forklift or crane to move
Yes, the amplifier has capacitors that will help handle the peaks. And from what I understand, amplifiers with more and larger capacitors can handle longer and louder peaks with the same PSU.
I don't really see why one could not add more buffers earlier in the chain if the problem is that current draw from the amp exceeds what the generator can deliver at peaks. From what I understand, using an inverter generator means it can handle louder peaks thanks to the capacitors in the inverter. I just watched a video the other day with David Lee from Bassboss where he made that exact claim.
I guess current drawn by the amp will be smoothed out already by the caps, meaning that the peak durations are longer than your typical audio rate signal. Perhaps the length of the kick instead of a waveform cycle. While additional caps before the amp would lessen the voltage dip they might not be enough to hold it steady for such long durations. But, at least in theory, since the online UPS should instantly balance the load between batteries and source, as long as the batteries has a sufficient discharge current, the system should be able to keep the voltage stable.
Sure, in practice I can totally see it not working out
Batteries might have to constantly charge and discharge at a quite high rate, which neither the cells nor the UPS might handle that well in the long run. If it is true that an inverter generator can deliver more peak power, it must be possible to take the inverter part and attach that between a diesel generator and amplifier.
Even if you cannot get the full 4x peak power I speculate about, to make only the inverter part but, but a bit oversized, for a resonable cost.
Just found now a online UPS claiming 10000w, https://powerwalker.com/product/10122127/ available here in Sweden from a big tech and office supply store for €1500, so not so surprising one can buy similar units directly from factory for about half that before import tax.
Eye roll, if some half wit is your guide.
There are plenty of them out there, just recently a friend sent me a Facebook post, how to repair LED bulbs by shorting blown LED.
I told him that it is cheaper to replace the board, costs 20 cents for a 9 W driver on board circuit, shorted LED will increase load on the others, and fail early.
When you send something out in the field, either you have a spare handy...or make sure it does not fail.
Your idea of using capacitor banks and batteries for peak shaving does not take into account the response rates of batteries and inverters, or the fact that there are correction circuits built in, which will try to control the fluctuations caused by varying load...
Stick to a larger oversized generator, and rent it rather than buy it, and that goes for the rest of the equipment as well.
There are plenty of them out there, just recently a friend sent me a Facebook post, how to repair LED bulbs by shorting blown LED.
I told him that it is cheaper to replace the board, costs 20 cents for a 9 W driver on board circuit, shorted LED will increase load on the others, and fail early.
When you send something out in the field, either you have a spare handy...or make sure it does not fail.
Your idea of using capacitor banks and batteries for peak shaving does not take into account the response rates of batteries and inverters, or the fact that there are correction circuits built in, which will try to control the fluctuations caused by varying load...
Stick to a larger oversized generator, and rent it rather than buy it, and that goes for the rest of the equipment as well.
Try this experiment: LM 1875, same music, same output, same volts 1A and 3A linear supplies, use a track like "Hotel California", you will find the 1A supply sags and the 3A does not do so.
Changing to a larger reservoir cap will also increase the current draw at idle, and increase the base load on supply.
And it can blow the chip, if too large.
So as above, stick to a proven method.
Changing to a larger reservoir cap will also increase the current draw at idle, and increase the base load on supply.
And it can blow the chip, if too large.
So as above, stick to a proven method.
Typical of the more powerful units, and the extra cost mentioned in the start post.
I prefer the version without internal batteries and stronger charger since I think a battery with LifePO4 cells might be better for the application than the lead acid that typically is used in UPS units.
I think you may have missed the point that the generator is NOT always available to rent if one of their big wholesale customers has it. In that case it’s Make Do or buy one of your own.
Look, a festival needs weeks of planning and preparation, you have enough time for arranging a power source.
It is not like you all are sitting around, and say grab your guitars etc, we will have a festival!
Here, we have festivals with fixed dates, as per calendar, or sometimes it is second Saturday of a particular month, so you know the date well in advance.
The performers also need to be arranged and dealt with, as does the lighting, car parking, food stalls and so on.
So power is just one of many things to be planned.
In India, temporary grid power connections are available at two weeks notice, they insist on safety precautions being in place.
In sum, the OP is somewhat incoherent or confused, he needs to sit down and do some planning, and if needed, call in an experienced person to do this.
It is not like you all are sitting around, and say grab your guitars etc, we will have a festival!
Here, we have festivals with fixed dates, as per calendar, or sometimes it is second Saturday of a particular month, so you know the date well in advance.
The performers also need to be arranged and dealt with, as does the lighting, car parking, food stalls and so on.
So power is just one of many things to be planned.
In India, temporary grid power connections are available at two weeks notice, they insist on safety precautions being in place.
In sum, the OP is somewhat incoherent or confused, he needs to sit down and do some planning, and if needed, call in an experienced person to do this.
I think I understand where Leo is coming from - only MONEY talks in terms of pricing and availability. Small potatoes aint gonna get the deal the Big Boys do. That may be different in India but NOT HERE.
I was able to arrange a temporary power feed at my construction site too. For $5800. Didn’t cost one red cent more to make it permanent, so I put a permanent meter base out there so they dont get to charge me another $5800 a year from now.
I was able to arrange a temporary power feed at my construction site too. For $5800. Didn’t cost one red cent more to make it permanent, so I put a permanent meter base out there so they dont get to charge me another $5800 a year from now.
Good point. Been in touch with a few suppliers now, and typically battery type to be used is specified to a specific type, or they will ask and fit the appropriate controller.
Admittedly I'm not that knowledgeable about batteries and how different types will perform in this kind of setup. LifePO4 cells seems like a good option because they can charge and discharge much faster, but not sure the UPS can make use of it really. Seems like especially the charging rate will be limited by the UPS rather than the battery.
Admittedly I'm not that knowledgeable about batteries and how different types will perform in this kind of setup. LifePO4 cells seems like a good option because they can charge and discharge much faster, but not sure the UPS can make use of it really. Seems like especially the charging rate will be limited by the UPS rather than the battery.