# Voltage and frequency



## k9luvr (Feb 11, 2016)

I just converted my 5500 running watt portable gasoline generator to tri-fuel. I'm experimenting with rich/lean settings on Nat Gas and checking voltage and frequency readings.

Just got it cranked last night & didn't get to experiment with settings much

Currently I'm getting 121V and 61 HZ at 3450 -3500 RPM with no load.

Is this good?


The generator has an AVR.
How much of a load should I apply while testing and what is an acceptable voltage and HZ output to not be worried about frying house electronics?


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## aandpdan (Oct 8, 2012)

Changing to a gaseous fuel should not affect the engine speed. The governor will still try to maintain 3600 rpm, unless you've changed some settings.

Is this a "snorkel" type setup?

I question your frequency/tach. 61hz is 3660 rpm. At 3500 rpm you'd be showing 59hz. It's common to set up a generator to run at 63hz with no load to account for governor "droop" when loaded.

59-63hz at 110-130 volts is a typical range for a portable, non inverter, generator. Most electronics use a switching power supply which can work over a fairly wide voltage range.

You should put a load on it while testing. Try it at various loads and note the volts and frequency.

I've also converted to a gaseous fuel. Your readings are "normal."


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## k9luvr (Feb 11, 2016)

I haven't changed any settings.
I used a US Carburetion kit- old style with solid metal donut, not snorkle.

I just put a new RPM/ hour meter on and the RPMS are ranging anywhere from 3400 to 3600. After running for several minutes, it seems to settle in the 3450 to 3500 range.

It is consistently putting out 121V at 61 HZ.

Is there a way to adjust the voltage and frequency other than tinkering with the rich / lean mixture of the gas?


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## KRE (Nov 29, 2011)

k9luvr said:


> Is there a way to adjust the voltage and frequency other than tinkering with the rich / lean mixture of the gas?


 Yes via the high idle and droop adjustments. If you do not know which/where they are or what your doing, do not touch them. Take it somewhere or research the how's an whys first, because if you adjust them wrong you can destroy the genset or anything it's powering if you make improper adjustments. Also never use unit meters as truth indicators, use nothing but high quality metering as these adjustments are the heart of the units output operational perimeters.


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## RonJ (Aug 5, 2015)

*Comments By KRE*

Welcome back, been waiting to hear your advice...really super. Ron


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## k9luvr (Feb 11, 2016)

> Also never use unit meters as truth indicators, use nothing but high quality metering


Can you elaborate or translate into laymen terms?



> Yes via the high idle and droop adjustments.


Don't want to get into "Droop", sounds too complicated.
High Idle sounds like something I could handle.
Can you explain or give me a link to the proper way to adjust?


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## KRE (Nov 29, 2011)

Your Metering? Use a quality hand held DVM, or O-scope, unit mounted meters are unreliable. High idle? I'll have to see a photo that shows the complete governor linkage to find your adjustment point. One point before we go any further, you will never get the HP from LP or NG that you get/got from gasoline, regardless of what you read anywhere. This includes hype from sales literature. When a/any engine with a high idle of 3600 rpm is converted to LP or NG, to do it correctly engine timing has to be changed as well.


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## k9luvr (Feb 11, 2016)

I have a fairly nice Extech meter. I've seen some tests that show it's with in tenths of the accuracy of a Fluke.

I've got the idle speed control figured out.

Didn't know timing on small engines was adjustable. Are you referring to a keyway adjustment?

If I were to try that, how much would I need to advance the timing?


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## k9luvr (Feb 11, 2016)

> I question your frequency/tach. 61hz is 3660 rpm. At 3500 rpm you'd be showing 59hz. It's common to set up a generator to run at 63hz with no load to account for governor "droop" when loaded.


I'm running at 3450 to 3500.

I do need to adjust the RPM. The manual that came with my generator, oddly enough does not list engine RPM. I looked all over the engine and no RPM sticker anywhere. Fortunately I was able to download a manual from the MFG website.

It states the RPM as 3750 +- 150.

So I think I need to boost the RPM to at least 3600.


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## KRE (Nov 29, 2011)

High idle on a two pole gen-set powering 60 hertz equipment has to be set at 3750 no load, because your machine has a 5% droop governor. As for timing, the easier the fuel is ignited and the faster the flame rate the less advancement of timing you need or want. No one I know makes off set keys that are sold for the different fuels. Most mfgs that offer tri-fuel or duel fuel engines have wires that are hooked or unhooked to change timing, as it's done with resistors, caps, or one mfg uses different coils at different locations.


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## Osviur (Sep 7, 2015)

*Hz.*

Hi k9luvr,

Just to clarify the information given by the respctable Senior members: In a 2 pole, synchronous generator, direct drive, as yours, each turn of the engine, is a turn in the generator (obvious), and each turn of the generator is one Hertz (Hz), so 3600 RPM means 60 RPS, generating 60 cycles per second or 60 Hz.This is an exact rule. 

The output voltage generated in the stator (static windings) is a direct function of the RPM's, the voltage applied by the AVR (automatic voltage regulator) to the rotating field (rotating windings), and the load.

When a load is connected to the gen, a current (Amps.) will flow through the stator windings, theese wire coils have resistance (Ohms) and a power lost will occur in the form of heat, and less volts, as a product of Amps X Ohms (aprox), reducing the effective output voltage . This load will present more mechanical resistance to the engine trying to reduce RPM.

This voltage drop must be compensated by the AVR in the generator, and RPM's by the governor in the engine to mantain the frequency or Hz.

With respect to the power obtained from a fuel:

1 Gal of gasoline gives aprox 114,000 BTU's 
1 Gal of diesel 128,000 BTU's
1 Gal of bio diesel 119,000 BTU's
1 Gal of LPG (propane) 84,000 BTU's
Natural gas is distributed in a gaseous form so is not easy to compare to a liquid fuel.

Ref: http://www.afdc.energy.gov/fuels/fuel_comparison_chart.pdf

Regards.


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## KRE (Nov 29, 2011)

Osviur said:


> This voltage drop must be compensated by the AVR in the generator, and RPM's by the governor in the engine to mantain the frequency or Hz.


 Very few rope start gensets have an AVR, most run a volts/hertz curve do to caps being the excitation design. Even those that do have a knee point setting where low hertz rolls off voltage, to assist the engine for motor starting or large load steps.


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## Osviur (Sep 7, 2015)

*Avr*

Hello KRE,

I read in the first k9luvr intervention that his generator has an AVR, so I assumed it as a fact. Having an AVR it is clear that it is a synchronous generator and the frequency generated is a function of the RPM's. Just this.

Receive my best regards and my recognition of your deep knowledge in this field.


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## KRE (Nov 29, 2011)

Osviur said:


> Hello KRE,
> 
> I read in the first k9luvr intervention that his generator has an AVR, so I assumed it as a fact. Having an AVR it is clear that it is a synchronous generator and the frequency generated is a function of the RPM's. Just this.
> 
> Receive my best regards and my recognition of your deep knowledge in this field.


So what are you trying to say?


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## Osviur (Sep 7, 2015)

*Clarifying*

Hi KRE,

What I'm trying to say is:

1.- The k9luvr generator has an AVR
2._ The k9luvr generator is a Synchroneous type
3._ This generator gives exactly 1Hz per RPS
4.- You know a lot in this field

Obviously English is not my original language so sometimes I may not be enough clear


Regards


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## Osviur (Sep 7, 2015)

*Clarifying*

Hi KRE,

What I'm trying to say is:

1.- The k9luvr generator has an AVR
2._ The k9luvr generator is a Synchroneous type
3._ This generator gives exactly 1Hz per RPS
4.- You know a lot in this field

Obviously english is not my original language so sometimes I may not be enough clear


Regards


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## KRE (Nov 29, 2011)

> 3._ This generator gives exactly 1Hz per RPM


 1 hertz per rpm would equal 3575-3750 hertz. The correct answer for a two pole genset is 60rpm = 1 hertz electrical (3600/60=60) 60hertz X 60seconds x 2 (top an bottom sine-wave peaks =7200) which is what a photo tach would read on a florescent light, that is being fed a 60 hertz sine-wave. What is your point with all this?


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## Osviur (Sep 7, 2015)

*Mistake*

Kre,

You are completely right, in my initial intervention I stated that 1 Hz equals to one TURN, then instead of clarifying I wrote RPM instead of RPS. Sorry I made a MISTAKE..and I'm going to edit and correct this mistake right now. Thank you very much for your observation.

Returning to the point:

One Hz equals to one cycle per second, so 60Hz means 60 cycles per second. A cycle (electrical) is a series of variations in a determined electric parameter, in this case Volts, that periodically are repeated. Each set of different variations is known as a cycle.

In a sinusoidal voltage wave, produced when the windings of the stator are cut by the rotating field of the rotor, in a progressive way, there is an alternation in the N and S poles passing in front of the stator windings, inducting an altenating voltage in the stator.

This voltage starts from zero, when both poles are at 90° electrical degrees with respect to the magnetic axis of the stator windings, rises up to align the axis, again decreases down to zero and then the opposite pole, to say south pole, approaches to the same coil, generating the opposite voltage, following the same path but inverted.

As we can see there have been a series of voltage variations continuosly different: Zero, max positive, zero, max negative, zero. From this point the next variation is a repetition (zero, max positive) of the previous series. Here starts a new cycle.

An electrical cycle comprises a positive half wave and a negative half wave. The measurement unit is the Hertz = 1 cycle per second, 60 Hz = 60 cycles per second, but each cycle has a positive and a negative HALF waves as you can easily see in your oscilloscope. 60 Hz or cycles per second have 120 half waves, and of course 3600 cycles will have 7200 half waves. 

KRE, I know that you are an expert in this field, but not only you read these lines, so I try to be didactic for many people interested in technical information, explaining in a very simple way electrical themes , hopping to be useful. Thanks for your attention.


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## KRE (Nov 29, 2011)

Osviur said:


> Kre,
> 
> You are completely right, in my initial intervention I stated that 1 Hz equals to one TURN, then instead of clarifying I wrote RPM instead of RPS. Sorry I made a MISTAKE..and I'm going to edit and correct this mistake right now. Thank you very much for your observation.
> 
> ...


When most folks find their self in a hole they quit digging. Google is not the be all in power generation as many a internet expert has found out. The problem with the internet is the amount of experts that pop up after key strokes. There are those in the US that are tired of the thief's copying or reverse engineering products then presenting their junk as top of the line gear based upon sales numbers. The only reason their junk sales is do to price and an uneducated consumer. When it gets real, only then will those country's get first hand effects of US ability. No one plays a trump card until it's required.


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## Osviur (Sep 7, 2015)

*Technical forum*

Hi KREE,

Please, let me remember you that this is a technical forum. I'm a 70 years old retired proffesional, who has been teacher of many young engineers. So think with calm what you say, and better talk about what is the technical matter, to help people needing valid information, easy to understand. I think respectfully, that this is the sense of this forum.

I will not respond to any other non technical comments , due to my respect to all the members and visitors of this site. 

Thanks for your comprehension.


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## KRE (Nov 29, 2011)

Osviur said:


> Hi KREE,
> 
> Please, let me remember you that this is a technical forum. I'm a 70 years old retired proffesional, who has been teacher of many young engineers. So think with calm what you say, and better talk about what is the technical matter, to help people needing valid information, easy to understand. I think respectfully, that this is the sense of this forum.
> 
> ...


Old American saying--------->The truth will set you free, but it is painful when going down sideways. My comprehension, is deeper than you'll ever know, nor do I mince words when people try to portray what they are not!


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## Enigma-2 (Mar 18, 2016)

Kre, perhaps I'm wrong, just caught you on a bad day, but, your post was completely unhelpful and mean spirited.


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## KRE (Nov 29, 2011)

Enigma-2 said:


> Kre, perhaps I'm wrong, just caught you on a bad day, but, your post was completely unhelpful and mean spirited.


Don't worry I'll never post on this forum again, as this will be my last post. I've better things to do now than trying to help out. I do not suffer people who pretend to know the bile that spews from their mouth. You guys have a nice life.


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## Enigma-2 (Mar 18, 2016)

KRE said:


> Don't worry I'll never post on this forum again, as this will be my last post. I've better things to do now than trying to help out. I do not suffer people who pretend to know the bile that spews from their mouth. You guys have a nice life.


Please reconsider your decision. There are always many different degrees of knowledge of the various members in these forums, and everyone knows something, no one knows everything. There must be a give and take, but in a civil manner. 

One of the hardest things I have to do in my job is how to explain a difficult technical topic to people who know very little about codes or standards. I have to reach them on the their level, not mine. Having extensive knowledge doesn't help if you can't relate your knowledge at the level of the recipient. 

Please reconsider as you so much to offer.


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