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Author Topic: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass  (Read 35761 times)

Steve M Smith

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #80 on: July 25, 2014, 12:11:09 PM »

That is part of what screenlightandgrip.com is offering.  240 from the generator to right next to the distro and a transformer at the distro to supply 120.

Assuming the correct plugs and other hardware are used I see no reason why the amps and powered speakers couldn't be run on 240 volts.  as you point out it would have less voltage drop because of lower current for the same power, and it would provide a even load to the generator

Here in England, that is just normal as our supply is 240v already.  I was thinking (note - not suggesting!) stepping it up a bit, perhaps 1000v, then stepping back down to 120/240 at the other end.

Probably not something to make up yourself but I'm sure the generator companies could find a safe way to do it.


Steve.
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Stephen Swaffer

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #81 on: July 25, 2014, 01:22:31 PM »

600 Volts would probably be a practical limit-that seems to be the voltage much equipment is rated for-including SO cable, etc.

The other factor in economics is the distance.  It takes the same step up/step down transformer no matter the distance.  Power transmission runs for miles.  I am not sure you would save much money or weight for even a 500 ft feeder (when you consider cost/weight of both cable and transformers) unless you were changing voltage by a factor of 10 or more.
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Steve Swaffer

Mike Sokol

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #82 on: July 26, 2014, 07:17:10 AM »

Beware the "sag".

All this talk of harmonics and neutral heating got me thinking about the differences between inverter generators such as the Honda units discussed here, and old-school constant speed generators with nothing but spinning copper and magnets.

So consider that many, if not most, modern amplified speakers use switched power supplies, there's going to be a non-linear load applied to the power source. In fact, plain old bridge rectifiers on a transformer feeding big capacitor cans draw power only on the peaks of the 60-Hz cycle (or 50-Hz for other countries).

While a constant speed generator that we might rent probably doesn't have electronic current limiting on it's output short of a circuit breaker, I'm sure that Honda and Yamaha inverter generators are constantly monitoring current and can go into limiting mode, much like our modern power amplifiers do to protect their output stages.

So can using amplifiers with switched power supplies on an inverter generator cause the generator to over-react to these non-linear currents (triplen maybe?) and go into current limiting, which reduces it's output voltage at power levels less than rated? That is, do you need to derate a 6500 watt generator to maybe 3K or 4K worth of non-linear loads (Mackie speakers with switched power supplies)? 

Scott Wagner

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #83 on: July 26, 2014, 05:06:16 PM »

Skye describes the set up as having the speakers all point inward from the corners of a 50' square.  He doesn't think they are pushing them that hard.
I realize that this is an Electrical forum, but this may be (another) key piece of the puzzle.  With speakers placed at the corners of a "50' square" facing each other, there will be noticeable cancellations.  This could, in turn, be causing the DJ to drive the system much harder than he thinks (just because it doesn't SEEM to be overdriven, doesn't mean it isn't).  Something else for the OP to consider.
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Scott Wagner
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Mike Sokol

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #84 on: July 27, 2014, 04:57:37 PM »

I realize that this is an Electrical forum, but this may be (another) key piece of the puzzle.  With speakers placed at the corners of a "50' square" facing each other, there will be noticeable cancellations.  This could, in turn, be causing the DJ to drive the system much harder than he thinks (just because it doesn't SEEM to be overdriven, doesn't mean it isn't).  Something else for the OP to consider.

This reminds me of a little music festival I attended with my kids maybe 10 years ago. Really small stage with a pair of Peavey 2-way speakers on sticks for mostly vocal PA. As I crossed the field in front of the stage I noticed that the vocals completely nulled out in the center. Of course I showed my kids this (11 and 9 and 9 years old, I think) and they had fun moving side to side a few feet and making the vocals disappear. The band was getting a bit worried about the four of us jumping side to side in front of the stage and laughing, so I told them they were just a science experiment (but they still ROCKED). When I explained to them that one of their PA speakers was wired out of phase and cancelling the vocals in the center, the didn't seem to understand and told me they borrowed the speakers from a little church up the street. Of course in a room you would have a lot of wall reflections to create "some" vocals in the center (even though all phase cancelled), but an outside field is nearly as good as an anechoic chamber for this sort of demonstration. Too much fun.   

Guy Holt, Gaffer

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #85 on: July 30, 2014, 02:25:49 PM »

I'm sure that Honda and Yamaha inverter generators are constantly monitoring current and can go into limiting mode, much like our modern power amplifiers do to protect their output stages.

A while back I tested both the Honda EU6500is and the Yamaha 6500 for limiters with a load bank and came up with some interesting results. Both machines have an electronic master breaker upstream of the overcurrent protection of the individual circuit breakers.  Where the master breaker in the Yamaha 6500 trips at 54A (6500W at 120V), the breaker in the EU6500is does not trip until 65A (7800W at 120V.) Further testing of the EU6500is with a load bank suggested that the actual continuous load capacity of the EU6500is is 7680 Watts. Where that is much higher than Honda’s stated continuous load rating (5500W) for the EU6500is, let me explain how we arrived at that figure in more detail.

First we modified the generator in order to tap the output of the inverters upstream of the individual branch circuits. Then following the load parameters as set forth in the manual, we used the generator's overload sensor to empirically test its' capacity with a load bank. The load parameters as set forth in the manual are as follows:

"If the generator is overloaded, or if the inverter is overheated, the red overload indicator will go ON.... When an electric motor is started, the red overload indicator may come on. This is normal if the red overload indicator goes off after about five seconds.... When the generator is operating overloaded, the red overload indicator will stay ON and, after about five seconds, current.... will shut off"

Gradually increasing the load with the load bank, we found that we could power a continuous load of up to 7680 Watts without the overload indicator coming on. When we exceeded 7680 Watts, the red indicator blinked intermittently. When we exceeded 7800 Watts the red indicator came on continuously, the limiter kicked in, and power was cut off to the receptacles after 5 seconds. Since, according to the Honda Manual it is normal for the overload indicator to come on for short front-end loads, like electric motors starting, our results suggested that the continuous load capacity of the EU6500is is actually 7680 watts (at first glance it seemed an odd number, but made perfect sense after further investigation.) When you consider that electric motors require up to three times more power to start than is required to keep them running, the manual suggests that the peak rating is actually well above 7680W.

Since our load bank tests suggested that not only is the limiter much higher than one would expect, but also that the inverter modules of the EU6500is generator are in fact capable of generating more power than is provided to us by the North American Power Output panel, we investigated the capacity of the EU6500is further and found that, in fact, it is engineered to generate 7680W of continuous power. In order to understand why it is possible with a modification to get that much continuous power out of a Honda EU6500is generator, one must first appreciate two things about the continuous load ratings given for generators. First, the factors generator manufacturers use to derive load ratings include not only the mechanical components (engine & alternator), and the electrical components (circuitry & wiring), but also the prevailing electrical codes of the market for which it is intended (where & how it will be used) and the brand image of the manufacturer (life expectancy of the product.) A quick survey of the wide range of continuous load ratings (5000W-7000W) of generators, by manufacturers other than Honda, using the same Honda GX390 engine as the EU6500is supports this fact. Second, when Honda engineered the EU6500is it was not only for the North American market. Like a car, Honda engineered a base model for the world market that they then customize for the different national markets. The difference between the various national models is primarily in the power output panel, which is configured according to the electrical standards and prevailing codes of the national market in which the generator will be used (use this link -http://www.screenlightandgrip.com/html/emailnewsletter_generators.html -  for more details on how generator manufacturers arrive at their continuous load ratings.)

When you compare how Honda outfits the comparable UK model of the EU6500is generator, the EU65, for the UK markets, where the standard circuit for domestic power is 240 Volts and 16 Amps (3680/3840 Watts), to how Honda outfits the same generator for the North American Market, where the standard circuit is 120 Volts and 20 Amps (2400 Watts), one realizes that Honda does not give us access to all the power available from the generator. That our empirical testing of the EU6500is revealed that it will power exactly two UK 240V/16A circuits (3840 Watts/circuit x 2 circuits = 7680W) is not just  a coincidence. An examination of the wiring schematics for the UK version, the EU65, reveals that the 7800W master breaker and load sensor alarm setting of 7680W are set for the equivalent of two UK 240V/16A circuits (2x3840W/circuit = 7680W.) It would make sense that Honda would engineer the base model to generate more power for national markets, like the UK, India, Australia, etc. that use 240V power. Unfortunately the power output panel of the North American model, the EU6500is, does not give us ready access to this power without the use of a transformer/distro because of our electrical standards and prevailing codes. Based upon these results, I can say with confidence that the OPs problem is not related to a limiter.

Guy Holt, Gaffer
ScreenLight & Grip
Lighting Rental and Sales in Boston
Cell 617-224-85634
[email protected]
« Last Edit: July 30, 2014, 02:30:15 PM by Guy Holt, Gaffer »
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Guy Holt, Gaffer

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #86 on: July 30, 2014, 02:28:29 PM »

All this talk of harmonics and neutral heating got me thinking about the differences between inverter generators such as the Honda units discussed here, and old-school constant speed generators with nothing but spinning copper and magnets…

The primary factors limiting the use of non-linear loads on portable generators are their inefficient use of power and the harmonic currents they generate. Because of their radically different designs, inverter generators, like the EU6500is, and conventional AVR generators, like the ES6500, react very differently to these factors. The harmonic currents generated by non-linear loads, in fact, have less of an adverse effect on inverter generators than they do on conventional AVR generators and so do not require de-rating as conventional AVR generators do.

Harmonic currents cause two major problems in conventional AVR generators: heat and voltage waveform distortion.  The first problem is that harmonic currents generate heat in the windings, core, and in the electromagnets of the rotor of conventional AVR generators. Since generator ratings are limited by allowable temperature rise, harmonics act as derating factors. In derating, the magnitude of the current is of obvious importance, because losses are proportional to the square of the current. Increased frequency causes increased core losses and increased copper loss from skin effect. 5th and 7th harmonics are the offenders here because they are in the 600 Hz range.

The second difficulty caused by harmonic currents is voltage waveform distortion. According to Ohm’s law, as each harmonic current encounters the impedance of the power distribution system, it will cause a voltage drop at the same harmonic voltage. Because, the capacitors of switch mode power supplies only draw current at the peak of the voltage waveform, this voltage drop occurs only at the peak of the voltage - leading to a flat topping of the voltage waveform.

The more harmonic content in the current, the more voltage distortion occurs throughout the distribution system. This includes the output terminals of the generator where the generator’s source impedance (particularly the subtransient reactance or “Xd”) will create the greatest voltage drops. If the flat topping distortion at the generator’s output terminals is severe, it can cause voltage regulator sensing problems (Self-Excitation or SE) and inaccurate instrument readings.

The effect that harmonic currents have on the generators is factored into the rating limits given them. How rating limits are affected by load can be illustrated in a “Limit Characteristic” graph that plots kVA and kW versus Power Factor. The fluctuations in the kVA line in the illustration below represent the generator’s operating limits depending on whether its load has a leading or lagging Power Factor. It is important to note that a generator’s Limit Characteristic graph will vary by the type of generator. The illustration below (courtesy of Caterpillar) is for a conventional AVR generator. Since the power quality of an AVR generator is intractably linked to its' engine - the effect of harmonics on the engine's governing system is the primary limiting factor. How the engine and its' governing systems are affected by lagging and leading power factor loads is illustrated by the engine kW limit line below.


A Limit Characteristic graph for a generator illustrates the effect of leading
or lagging Power Factor on the generator's output.
 

What this generator’s Limit Characteristic graph tells us is that, operating a capacitive non-linear load (the leading power factor quadrant right of the Unity Power Factor center line), this AVR generator first reaches a thermal limit as a consequence of heat generation in the generator's rotor from harmonic currents. And since, conventional AVR generators regulate voltage by means of a power feedback loop from the generator Stator (via the Sensor Coil), through the Exciter (Voltage Regulator), to electromagnets in the Rotor, Armature flux generated by harmonic currents in the Stator leads to erroneous Self-Excitation (SE) and therefore voltage. Put simply, lower power factor loads cause instability of the generator’s voltage output. Finally, since there comes a point as the Power Factor of the load decreases, when harmonics inhibit the successful operation of the generator’s Automatic Voltage Regulator all together, and hence the generator’s capacity to generate any power at all, the kW output eventually drops to zero. Since the voltage instability in conventional AVR generators is a function of the non-linear loads they power, the conventional wisdom is to limit the amount of non-linear loads it can power by roughly half of the generators capacity.


The Limit Characteristic graph for an Inverter generator.
Note the negligible effect that leading Power Factor loads have on the generator's power capacity.
 

As the Limit Characteristic graph for an inverter generator above illustrates, it is a completely different situation with inverter generators. Because the speed of the motor is always changing, inverter generators cannot maintain voltage output by the conventional means of regulating the excitation current in Rotor electromagnets. Instead, inverter generators use permanent magnets in place of electromagnets. 
A permanent Magnet is an object made from a material that is naturally magnetized (Neodymium in this case) and hence creates its own persistent magnetic field. Since permanent magnets do not require an excitation circuit, armature flux created by harmonic currents will not cause voltage instability as it does in conventional AVR generators.


Left: Conventional AVR Generator w/1200W non-pfc electronic ballast. Right: Inverter Generator w/1200W non-pfc electronic ballast.

And since the generator’s inverter completely processes the raw power generated by the permanent magnet (converting it to DC before converting it back to AC by means of a micro-processor), the AC power it generates is completely independent of the engine. By switching IGBTs according to Pulse Width Modulation control logic, an inverter generator is much better able to sustain output voltage against transient loads and, therefore, it has a much lower internal reactance compared to conventional AVR machines. Finally, since the Impedance encountered by harmonic currents that causes voltage waveform distortion is a function of the internal reactance of the generator’s engine to changes in load, a second benefit to using permanent magnets in place of electromagnets in the generator’s Rotor is that as is evident in the oscilloscope shots above, inverter generators consequently are much less susceptible to voltage waveform distortion.


TABLE COURTESY OF KIRK KLEINSCHMIDT.

The end result is that leading power factor loads do not cause voltage regulation errors in inverter generators as they do in conventional AVR generators. Inverter generators are able to hold their voltage stable within ±1% of the mean voltage, as opposed to the ±3% of conventional generators using analogue AVRs and are much less susceptible to voltage drop and AC Frequency (Hz) as a function of load (see table above.) 

The rock solid power and low sub-transient impedance of inverter generators enable you to operate larger non-linear loads on them than can be operated on conventional AVR generators. For instance, we have struck 6kw HMI Pars on a modified Honda EU6500is inverter generator without problem.

These power quality issues have been vexing film electricians for years, to learn more about how we have learned to remediate the adverse effects of harmonics read a white I have written on the use of portable generators in motion picture production available at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html.

Guy Holt, Gaffer
ScreenLight & Grip
Lighting Rental and Sales in Boston
Cell 617-224-85634
[email protected]
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Guy Holt, Gaffer

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #87 on: July 30, 2014, 02:32:19 PM »

… can using amplifiers with switched power supplies on an inverter generator cause the generator to over-react to these non-linear currents (triplen maybe?) and go into current limiting, which reduces it's output voltage at power levels less than rated? That is, do you need to derate a 6500 watt generator to maybe 3K or 4K worth of non-linear loads (Mackie speakers with switched power supplies)?

Since the harmonic currents created by switch mode power supplies react poorly with the high impedance of conventional AVR generators (illustrated in the Limit Characteristic graph above), the conventional wisdom is to limit the number of non-linear loads you use on them to roughly half (65%) of the generators capacity. An inverter generator by comparison can be loaded to near capacity with non-linear loads because the extremely low harmonic distortion (less than 2.5%) of the original AC power waveform of inverter generators and low sub-transient reactance results in virtually no distortion of the power waveform (use this link - http://www.screenlightandgrip.com/html/emailnewsletter_generators.html -  for more details about the adverse effects non-linear loads have on portable generators and how it affects their continuous load ratings.)

Guy Holt, Gaffer
ScreenLight & Grip
Lighting Rental and Sales in Boston
Cell 617-224-85634
[email protected]
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Barry Singleton

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #88 on: July 30, 2014, 11:26:26 PM »

  Hello Guy;

  I didn't jump in before the other thread closed so I will take this opportunity to thank you here. I read the entire news letter that you were so kind to share with us over several times and learned a TON!!! 

  A mere thank you does little to express my sincere appreciation for your work, knowledge and generosity.

  I need to get it in a PDF and saved for ever!

  All the best,
                     Barry.
 
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shawn swanson

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #89 on: June 27, 2017, 01:15:20 AM »

I would like to thank everyone for all the information collected here, and bring y’all up to date in hopes I can learn a bit more.
I’m the OP of this thread.  I’ve learned a bit more about the sound system, electrical stuff and how the sound system is used.  I’ll detail this and then ask about a possible upgrade/change and how it may affect the set up.

Here is what we (I am now part of the camp and I manage the PA) are working with.  Honda EU6500 as stated.  Gen is set to 240v and we run with the Eco Throttle off.  An 8/3 SO cord of 110 feet plugs into the twist lock and runs to a jbox.  In the jbox (2) 10/2 SO cords are wire nutted to spit the 240v into (2) 120v circuits.  In other words, (1) 120v circuit is tied to Black and White while the (2) 120v circuit is tied to the Red and White.  Each 10/2 is about 50’ long and ends in a quad outlet box.  At the quad outlet box (1) SR1530 is plugged directly in, and the second SR1530 is plugged in via 75’ to 100’ of 12 ga extension cord.  This same configuration is duplicated on the other 10/2 cord.  An old school 1202 mixing board and any computers used are plugged into one of the two 10/2 cords.  The two Mackie 1501 subs failed and have been taken out of the PA system.

Last year I upgraded the main run from the gennie to the dance floor from 10/3 to 8/3 and shorted the run to 110’ from about 150’.  I used the 10/3 to make the splits out to each side (called 10/2 above since I only use one hot and the neutral).  This year I will buy a small Cutler Hammer CH main lug panel and use it to create a distro box.  Other than having over-current protection via the breakers, I don’t see this as being electrically different than the wire nutted set up above.  Can the act of installing a panel with a main bus and neutral / ground bars effect things like any load carried back on neutral, or shift return current from the neutral to the opposite leg?  Can it effect any ‘triplen harmonics’ or other issues possibly caused by a nutty jbox?  Put aside that this is Burning Man and there are LOTS of trippin’ harmonics…

The gennie is run out 100 feet from the floor because we will hear it otherwise.  We play a unique set of music, ranging from Ludovico Einaudi to Black Eyes Peas to Skrillex to Afro Celt Sound System to Carlos Nakai.  Well, I’ve never actually heard Skrillex on our floor, but other intense Dubstep.  In the middle of the set no one will notice the gen but it can be heard during quite piano and the like.  I *wish* I had thought to run the dam gennie out to the floor and try taking the 8/3 out of the equation like Mike suggested! 
Even after going to 8/3 and shortening we still get the volume drop when pushing the system.  I try to keep the DJ’s from compensating by turning it up louder and most comply.  I notice that the effect increases when the volume is pushed harder.  I have also noticed that some DJ rigs have less of a problem than other do.  I am assuming some rigs put out more signal power and that helps the amps not work as hard?

The transformer/distro Guy talks about sounds great but I’m afraid to inquire as to how much it costs.  According the his post #62 I can set the gen for 120v operation only and the two internal inverters with run in series to increase the 120v capacity and balance the load.  The manual show that I can use two specific receptacles on the face of the gen and tap each one of the inverters.  Would it help to run a second 8ga cord, skip the distro and run the two sides of the dance floor all the way back to the gen?
We do play a fair amount of EDM with all the other sweet and wacky stuff (Cake’s version of Mahna Mahna is a favorite of mine).  Are there tricks for dealing with overworked voice coils?  Other than turning the music down…  I’ve heard of electricians using a ‘buck boost box’ on long extension cord runs to keep their hole hawgs happy with full voltage.  Would getting a couple of these and boosting voltage help with overheating?  It might help with delivering watts, right?

Now for the change part.  The EU6500 has to be carried out to the desert and back each year and that has become an issue for the person who does it.  We are hoping to find a way to leave out gen with the rest of our gear.  Our camp has two shipping containers that we store our stuff in.  These two containers stay in the desert all year (or in the general vicinity).  Because the containers are subjected to some wild temp swings throughout the year we do not leave the PA in them.  We also do not leave the gas powered EU in there.  Our camp has raised some money this year and I’m thinking of changing to a Generac propane powered 11kw or 14kw household back up generator.  A Guardian series.  My hopes are two fold; I would have enough head room to be sure to meet the power need, and we could mount the thing to a pallet and leave it in the shipping container without it’s tank or battery.  Each year we change the oil, connect the charged battery and a fresh tank and away we go.  Or so I hope.  Does anyone have any thoughts on this?  Generac tech support is no help at all.

Thanks again for all the discussion on this thread, and for the forum!
Shawn
« Last Edit: July 09, 2017, 06:32:53 PM by shawn swanson »
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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #89 on: June 27, 2017, 01:15:20 AM »


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