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New Honda EU7000


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#1 Eric Jaspers

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Posted 21 August 2014 - 10:20 AM

Anyone had a chance to parallel  the new Honda EU7000 yet. It is about time they offered paralleling capability in the larger models like they have in the smaller ones. If it works well, it should be a real game changer.

 

Eric Jaspers 


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#2 Guy Holt

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Posted 26 August 2014 - 06:14 PM

Anyone had a chance to parallel  the new Honda EU7000 yet. It is about time they offered paralleling capability in the larger models like they have in the smaller ones. If it works well, it should be a real game changer.

 

Eric Jaspers 

 

We have the new EU7000 as well as a number of EU6500s. Comparing them side by side here is what we have found:

 

With a fuel injector, the EU7000 is considerably more fuel-efficient than the EU6500. The new model also is equipped with a 5.1 gallon gas tank and can operate for six hours per thankful of gas at rated load or an estimated 18 hours at ¼ load.

 

With redesigned airflow, the EU7000 is a little quieter than the EU6500. By refining the  triple chamber construction and centralized intake/exhaust system of the EU6500, the EU7000is achieves a better noise specs than the even super quiet EU6500.

 

In paralleling operation, the EU7000s (like the EU6500s) require that you be able to adjust their load sharing because the generators do not pick up load equally. For example, when we first tested the generators they split the load by a factor of 3-to-1 (i.e. if the load was a 1200W HMI, one generator picked up 900W while the other picked up only 300W.) Loading them equally is critical to their successful operation in paralleling applications for the following reason:  since both voltage drop as a function of load (voltage droop), as well the amplitude of the current harmonics a generator operating in parallel will shoulder, is a function of the percentage of the load it picks up, unequal load sharing increases the discrepancy between the voltage waveforms at the output terminals of the generators – leading to the generation of more neutral cross current  (with a larger 3rd harmonic component) that will circulate continuously between them (see illustration below.)

 

Paralleling_Copy_Circulating_Cross_Curre

 

The problem with these "watt-less amperes" is that they can interfere with normal operation. For example, since the circulating cross current is superimposed on the load current passing through the generators’ circuit breakers, cross current can cause a breaker to trip unexpectedly as the breaker "sees" the actual combined amperes and not just that drawn by the load. The harmonic components of this cross current that circulates continuously between the generators can also cause their inverters to overheat and potentially burn out prematurely. In our preliminary test described above, when the load on the generators was shared unequally (by a factor of 3-to-1) there was a 100% increase in the generation of 3rd harmonic cross current, which translates to a 400% increase in heat generation. This is clear evidence that equal load sharing by EU7000s operating in parallel is critical not only to their success but also their longevity.

 

These power quality issues have been vexing film electricians that have been paralleling the MQ Studio Units for years. To learn more about how to remediate the adverse effects of harmonics in paralleling applications, use this link to a white paper I have written on the use of portable generators in motion picture production.

 

Guy Holt, Gaffer

ScreenLight & Grip

Lighting Rental & Sales in Boston


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#3 Edward Lawrence Conley III

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Posted 03 September 2014 - 11:22 AM

Hi Guy,

 

From what I'm reading the parallel operation doesn't really offer any benefit to us unless we utilize a distribution center like yours.

It will only provide 1- 240v circuit and at rated 5500watts/11,000 combined we get a 45.83 amp 240v circuit that uses the CS style connectors.


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#4 Guy Holt

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Posted 03 September 2014 - 05:09 PM

Hi Guy,

 

From what I'm reading the parallel operation doesn't really offer any benefit to us unless we utilize a distribution center like yours.

It will only provide 1- 240v circuit and at rated 5500watts/11,000 combined we get a 45.83 amp 240v circuit that uses the CS style connectors.

 

That's correct. Honda restricts the loads to be powered by their paralleling box to 240V single phase loads because they return no current on the common neutral that will circulate continuously between the machines. This "cross current" is the biggest impediment to paralleling two Honda EU6500s or EU7000s. The no-load cross current generated by the disparity in the voltage waveforms of the generators is 180Hz  to begin with and so generates exponentially more heat than if it were 60Hz current.

 

EU_6500_Parallel_Pkg_Sm.jpg

(Parallel operation of two Honda EU6500 generators made possible by our new Paralleling Control Box)

 

If the load being powered also generates 180Hz 3rd harmonic current (some Kinos, LEDs, and all non-pfc HMI ballasts will)  the heat generated will increase even more since the two 180Hz  currents (the 180 Hz component of the no-load cross current and the 180 Hz component generated by a non-linear load)  are additive.  Where cross-current  circulates continuously between the generators, if it has a high 3rd harmonic component it will cause the inverters to overheat and fail because it generates heat exponentially.  Honda's solution is to restrict paralleling operation to 240V loads that won't add to the 180Hz no-load cross current.

 

Paralelling_Copy_Trans_Gen_Isolation.jpg

(Our Transformer/Distros isolate triplen harmonics from the generators so that they can not elevate cross current to a hazardous level.)

 

To power 120V loads off of paralleled EU7000s requires a step-down transformer like our Transformer/Distros.  A step-down transformer will both create the required neutral connection for smaller 120V loads, but at the same time isolate the generators from the 3rd harmonics created by these loads that would otherwise lead to elevated cross current, hot conductors, and overheated inverters.  By isolating the generators from the 3rd harmonic currents generated by 120V non-linear loads, a step-down transformer  makes it possible to power 120V non-linear loads on paralleled generators without  over heating the generators inverters.  Use the link for my white paper above for more details.

 

Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston


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