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View Full Version : anybody ever power their system with a generator?



scott fitlin
06-02-2003, 07:59 PM
Just wondering if anyone has experience with gensets. And IF anybody has used a generator did your equipment sound as good as Municipal power? Anybody?

Tom Loizeaux
06-02-2003, 08:12 PM
Generators are theoretically capable of delivering 120 volts @ 60Hz. If this were true, then your system should sound fine. In reality the smaller plants are less stable in terms of voltage and quite unstable in terms of frequency. Larger truck mounted plants, especially "crystal controlled" units deliver a stable 60Hz. These plants are used in film and television production but are not common or can be expected at state fairs, etc. Though most electronic equipment has some tolerance for voltage and frequency fluctuation, you should be aware that top performance is often compromised and there can be a risk of damage if the plant is allowed to fultuate significantly.
Have I tried it? No, but I do use the high end plants regularly in film production lighting that require a precise 60Hz and these high end plants are quite reliable.

Tom

scott fitlin
06-02-2003, 08:22 PM
I am considering converting my buisiness to self generation! I would require an 800KW natural gas gen. The ones Im looking at have precision micro-computer controlled voltage regualtion and frequency stability.

My Con Edison power vary rather greatly and this affects performance of ALL my equipment, not just audio! Sometimes my Con Ed power is as high as 139 volts line to neutral!!! And sometimes its just weak at 111 volts!

The real reason I want to convert is the cost. Con ed has gotten way to expensive! I am on a demand meter, and Con Ed hikes the prices during the summer months. Last July my electric bill for my buisiness was $14,789, compared to natural gas estimates of around 3-4000!

The generator Im looking at is $179,000 financeable, and i figure I can pay it off in 5 years and come out ahead!

I was just wondering does stuff work the same off generator power, like municipal power!

Thanx, Tom.

martinleewin
06-29-2003, 06:17 PM
AC 800kW of audio? I want to see that! Let's see.. 100W for 100+dbSPL @ 1m and using the inverse square law says... I will listen from a mile and walk my way in--stopping before the threshold of pain. I will bring a bigars image-stabilized telephoto lens. But even that would be vibrating too much in midrange for a clear photo!
But seriously, I have done consulting work for manufacturers experiencing equipment trouble ultimately traced to unreliable power.
Aren't you on a submain of 2kV or more? 6.8kA @ 117V (by my Watt's Law calc) is off the chart on wire gauge. The voltage reg should be much better on a submain than residential service because you get a straighter shot from the substation that way.
Have you complained to Con Ed? PG&E here in NoCal will upgrade lines to commercial customers at no charge. You must complain or they will not recognize a problem. Submit a printout from a power disturbance analyzer as evidence. You can rent a Dranetz or similar unit for a month and it will report anything outside of the thresholds you set.
Ask for a dedicated line. This solves 95% of utility power issues.
They ought to do an upgrade to keep your business. You should not have to install a ferroresonant stepdown transformer at your service entry just to get +/-5% voltage tolerance. You can always drop 'em later for cost reduction and self-reliance.

For the kind of money and technology you would be spending, the gen voltage will be much more stable (a few %) than your utility tolerance and the frequency will be much better than low cost portables. I would venture 0.5% (0.3Hz) worst case--but don't quote me on that one. Get it in writing. Utility frequency reg is usually quite good at around 60+/-0.02Hz until they react to big load changes by switching generators in and out. Then the big 59-61 Hz meter needle will bounce a few degrees for a few seconds.
Synchronous motors and circuits using line frequency for critical timing will be most affected.

Only poorly designed instrumentation should be affected by voltage fluctuations of +/-5%. These can be given local ferroresonant power conditioners if necessary. Ferrores will output pretty stable voltages over a 90-140+ voltage input but can not correct the frequency, Kenneth. Most audio gear is tolerant of +/-1 Hz or more and +/-5% voltage as those are long term shifts into an analog power supply. Dropouts can cause momentary dips/gaps in amp output and resets in processors.
The real concerns are disturbances from surges >150V and lightning strike spikes. Valuable and sensitive equipment needs good overvoltage & transient protection for these events. Two different circuits are required for full protection. Of course, growing your own keeps you safe from all those external events and brings them inside--as in maintenance. Oh-- when was the last time your lightning rod system bonding was inspected? We would hate to see all your equipment AND your new generator get fried!

Other facts;
You had better figure on substantial nat gas price increases in the next few years. We have been importing from Canada as long as they were selling cheap. Canada's reserves are about half gone now. The U.S. has more gas in the ground, but it is scattered around more and is more expensive to tap. Now that the prices have more than doubled the U.S. producers are starting to turn on their spigots. Canada has a 20 year supply at current consumption and the U.S. has 30. The air pollution quotas are pushing more utilities and smokestack industries to nat gas and this will raise demand and prices even in a recession or depression.
It takes a while for the utilities to pass on price increases when they are state regulated. Electricity produced by nat gas will go up in price as well, but not as much.
Martin W.
Wizard Labs

scott fitlin
06-30-2003, 12:37 AM
Your saying that If I got a small dedicated service from con ed in addition to my 800 amp service, and just had my sound system on the dedicated service that would solve certain power issues? It definitely wont solve any cost issues!

I am entertaining this thought, but Con Ed is way overpriced and it may actually be the move to get rid of them and go self generation!

martinleewin
06-30-2003, 10:16 AM
Is it 800A or 8kA (=800kW) service you are talking about? The larger amount gives you some bargaining power with Con Ed was my point. An EXTRA dedicated line would definitely be a charged item (sorry for the pun). I do suggest you consult with an electrical contractor experienced in this field or a consulting engineer, such as myself, before you barge ahead on a power plant project. This is a chat board where you get specific advice on loudspeakers-- and you often get more than you pay for.

I can provide some more "free advice", although you have not really described your electrical usage requirements much less your audio requirements. Are you Recording? Post-production? Broadcast? PA?
Are there other local activities to cause load changes or noise? Especially motors, air compressors, and switch-mode power supply equipment "nearby" can be causing local problems. These applications and complications have much bearing on the topic for your situation.

More general information...

For strictly audio concerns, good voltage stabilization with ferroresonant tranformers to keep the voltage in line for the Con Ed problems is a possible solution. The additional transient protection suggested before is for insurance against Con Ed screwups (voltage surges) or natural disasters (lightning spikes). Now you have taken care of 2/4 of the utility supply problems. The 1/4 of the problem not to worry about for audio is frequency.
Plus or minus a few Hertz or percent is not to worry.

When line power is that bad, line-conducted NOISE is often a problem. This will affect sonic quality in a big way. This 1/4 of the line problem can be most annoying and perplexing. Lower frequency hums and buzzes will be obvious. Higher frequency noises, most often caused by in-house sources, are sneakier. They will muddy your midrange tones and cause subtle IM/THD distortions you would never suspect or be able to track down in shop tests.

Ferroresonant transformers cut noise by 4-8 dB by their inductive nature. That may not be enough to render heavy line noise inaudible. Good commercial transient suppressors include an inductive/capacitive T-filter to cut noise by 6-12 dB. Better EMI filters cut line-conducted noise by 20dB. These are add-ons to cure substandard electrical service or venue (local disturbance/noise) problems. BTW (if you are not an EE) 3dB=2:1 electrical signal difference. Speaker sound pressure levels (SPL) apparent to the human ear are 10dB=2:1. But electrical noise is relative to the desired signal and has maximum undesirable effects.

There is another remedial power solution called Uninteruptible Power Supply (UPS). These come in two versions. A standby system will use line power until a deviation is detected-- at which point it switches to battery inverter mode. The other type is a full-time battery inverter system where line power is only used to keep the batteries charged.
UPS units are not generally used for audio systems. After all, if the house lights, or production computers, or whatever goes down in a blackout.. who needs audio? I tried using my puny home (for my Mac computer) 650VA UPS unit to drive my 900W PA rig on a gig once. I would have needed another to supply my bass guitar rig-- but this was an experiment. It ran hot and did the job. It did trigger to kick in battery/inverter reserve supply a couple of times; most likely because of line sags caused by the PA plus multiple guitar amps sharing two house circuits.

martinleewin
06-30-2003, 12:22 PM
I did not mean to represent myself as an expert on the power industry or generator technology in my previous post. So the power market info provided by me is part general market research and substantially anectdotal. My experience does include tracking down electronic equipment performance issues including many power line causes.

Bo, we meet again! Your more thorough statistics from industry sources are accurate for the present time. I live in the land of PG&E, deregulated to the point of stupidity on the supply side and still regulated on the customer side, bankrupted by out of state gougers. Their service has gotten better lately and almost back to pre-dereg levels. I have an excuse for being skeptical of energy industry market tactics. We do not expect much relief from the current administration, considering where they are coming from.

I had researched the natural gas market for investment purposes well before Mr. Fed made it a coffee clache topic. I got a couple of small natural gas production companies I expect to hold for a good while. They are SLOWLY turning on their spigots to fill the supply/demand spread. Many other domestic oil/gas property operators have been exploring, acquiring and developing reserves for decades-- pumping oil when the price is right and holding the gas until lately when the gas price has exceeded 4 or 5 dollars. Nothing illegal or unethical here-- just patience and market timing.

Pipeline routes and capacity are a limiting factor as boputman points out. They are much harder to get local approvals and build out compared to electrical lines. They should be fully developed by the time the supply is depleting and prices are even higher. Future routes will need to payback in a shorter time, well short of their life cycle, because the domestic supplies could be exhausted by then. Then the LNG importers will control the sources from seaport terminals and the distribution patterns will shift to take advantage of local market needs. It is a developing shell game with this non-renewable natural commodity.

Many commercial customers were sold excess capacity on their gas generator units. "The excess power can be sold to the local grid operator for a nice ROI payback" they were told. Now the power companies are lowering their electricity purchase prices for these cogenerators. Another reason to look beyond current pricing in your cost calculations.

I threw that in so the moderators would see some commercial audio linkage as we get well off board discussion topics. They have not "pulled the plug" on us yet so they must be still amused and watching to see where this thread goes. To reign us back in...

My basic advice is in line (oops, did it again) with boputnam. Essentially; to establish the route causes of your power problems and cost/benefit localized house circuit and service upgrade measures before ditching Con Ed in a 30 year commitment kind of way. The prior request for what kinds of equipment you have is needed to begin understanding the nature and scope of your situation.

Remember; you usually get what you pay for on advice and other matters. A local consultant with power quality experience will be a much more practical and cost-effective way solve your problems quicker. I don't mind supplying free advice for general consumption up to the point it is useful for others to understand similar issues they may be facing.

All service supply quality or treatment measure suggestions are either general or speculative without more info. Even then, we could not really troubleshoot over the internet... unleeeeess... you get a power disturbance analyzer with Ethernet I/O & an IP hookup linked to web server software so we can see the glitches as you move it around from circuit to circuit and tell us what the house loads are doing. We would be happy to log into www.scottspowerproblems.net for remote monitoring. Otherwise, you can let us know what the contractor or Con Ed did to help and what it cost you. At least you should have a better knowledge base of power quality issues by now.

Over,
Martin W.

scott fitlin
06-30-2003, 02:55 PM
BUT, I am not thye only one here in Coney Island who has had major problems with con ed power. The 2 big parks went to generators years ago! Unfortunately, Con Ed cuts available power on hot days. But we have Rides with BIG motors and transformers! Con Ed can burn your equipment and it has happened. They blew a 12 1/2 ton AC compressor for me 2 years ago. This last weekend on e of the new rides couldnt run properly because the line power was undervoltage and caused the step up transformer to burn!

I have a big service ( 800 amp ) and we run 60 tons of air conditioning as well as 40 bumper cars, 125 video and arcade machines and signage and lighting! Oh yea, my audio system too!

+ - 10% is what most gear is rated for as far as tolerance, but I have clocked my power as high as 140v line to neutral. I have made major complaints to the power company. They have had their power quality monitor on my lines and they have seen whats there but say they cant do anything about it!

For what Im spending per year to Con Ed ( 43K annually ) I CAN finance the 800KW gen and come out better in a five year period! We do have the gas lines and can support such a big unit! Remember, this is a commercial area that has big gas and electric runs!

Now I talk to the guys who have the Wonder Wheel and the Park with the Cyclone Roller coaster! And everyone was blowing motors and stuff just wasnt operating properly when they were Con Ed powered! Once they went self gen all these problems vanished, save for normal wear and tear, and fatigue!

COST is whats driving me! Even in the dead of winter while being closed, and using negligible power, my AC bill runs 1400 per month. Demand meter. Im paying for it being there as opposed to what I actually consume! And my bill can never go BELOW 1300 per month!

Another guy I know suggested a Buck/Boost transformer, but I dont know!

I also dont care about selling power back to Con Ed! I can finance this gen set over five years and come out ahead. My gas costs will be cheaper than Con Ed, and I can use what I pay to con ed to pay for the gen which I OWN after its paid off!

On a hot saturday or Sunday my building is pulling 500 amps!

boputnam
06-30-2003, 03:16 PM
Boy, howdy...

With all the anecdotal positives from the other parks, I'd guess you're "good to go"...

And, I think I might be tall enough to ride - that is, once you convert to reliable, and more cost-effective power! Let us know! ;)

martinleewin
06-30-2003, 09:21 PM
Ok, Scott. Now we can appreciate your situation better now with this info. The downtime and maintenance costs of Con Ed's problems for you seem to tip the balance in favor of going with gas gen.
Both boputnam and I have been making sure you understand that natural gas rates have tripled in the last couple of years as everybody is jumping on that bandwagon. Nat gas rates are likely to outpace electricity for the forseeable future-- only the exact price growth differential is unknown. Just allow for that in your ROI analysis.
Bo was quoting the Houston-centric report obviously intended for congressional consumption with an agenda to establish the Gulf area as the nation's primary supplier for LNG imports from Atlantic Ocean sources. The market and energy policy timing is right for them to make their power play now. Their energy reserves are rapidly depleting and they want to have a business to operate before too long.
Our opinions differ only as to how successful the Houstonites will be in the long run vs. other regional providers, independent locals and Pacific Ocean competitors sure to grab pieces of the U.S. nat gas market. The pipeliners must place their regional supply point bets with the best prospects well in advance. They will hedge their bets if they can and if they are smart. Routes without a captive prime supplier and connection points will lose out bigtime like the regional railroads experienced as the Industrial Age matured. Regional transportation supply disruptions can cause commodity prices to skyrocket temporarily until those operators are swallowed up by the fittest.
And be sure to include in-house or service contract costs for the gen in your budget. Get manufacturers' and independent service providers' quotes for long enough periods of service. Buying a long term service contract with yearly payments is usually a favorable way to go. Cancellation terms must be considered then. Insist on performance criteria in proportion. The costs in summer shutdowns and burnt equipment could easily make that expense a cool breeze.
Your audio equipment will be half as happier as the motors and drives with the stabler voltage source. Audio DC supplies tolerate voltage drift fairly well. Amplifier under/over voltage only affects sustained peak power output proportionately. Burst power is a function of the amplifier DC power supply capacitors only. Digital equipment will appreciate the voltage stability very much.
Good house circuit feeder isolation will provide some immunity from local noise & sag/surge line conductance effects from those motor/drive units. Once the source power is stable, you can reevaluate the need for power treatment on the audio gear or other sensitive circuits. Local noise ought to be the most prevalent audio line power issue then (if at all).
Line frequency specs will only matter to the synchronous motors or crude instrumentation designs relying on precise power line timing. Line frequency within a few hertz never bothered any audio gear (as I have maintained in my statements, here). Generator frequency specs need not be better than typical (good) utility specs for your application. I would not pay extra for crystal-controlled power synthesis unless you had some super-sensitive equipment-- as the responder doing lighting effects required for their application.
So... to sum up; you may not hear much noticeable difference in your audio system performance for the better. It will not be worse... the system was not described. It is not important; but this is an audio discussion forum. We care about fellow audio consumers and professionals. Let us know how it goes.
You should sleep better at night knowing your business is not at the mercy of a local power monopoly who does not give a flying *#@! (expletive deleted) about its customers.
Good luck,
Martin W.