Genset voltage reg: capacitor vs. AVR

I did write "related". ^_^

TDD

Reply to
The Daring Dufas
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Many of the transformers and other circuitry in lower manhattan are still being put back up. Most of that stuff was underwater (salt water) south of 32nd street. I wonder if he's reparing generators. I'd repair the diesel ones. There'd be more money in those, but stick to repair manuals and their one eight hundred tech numbers.

Reply to
Transition Zone

You mean whether the cap is shunted to the load and power source? Because "in conjunction" means "in series with" right? At least, that's how I've heard it mentioned before.

Reply to
Transition Zone

Do you have a link to a site that sells the AVR ditty? If it's regulating the field current of the generator in response to the generator voltage, and if all the genset does is rely on the motor's governor for speed regulation, then it should give better regulation.

But I can only speak from a combination of a deep knowledge of control systems theory, a reasonably deep knowledge of how generators work and how Briggs and Stratton engines work, and a near total ignorance of how people actually put these things together in practice.

Reply to
Tim Wescott

Thanks for the link. From that thread, I determined that the keyphrase I needed to google was "alternator feedback capacitor".... That gave me the link to a paper called "Field Initiation Design Fundamentals for Pulsed Alternators" which has an abstract giving a short explanation of how the capacitor works. This was an IEEE paper.

It is simply a bootstrap giving feedback to the field of an alternator....... Not a particularly good regulator, but sufficient for non precise applications. I had never seen this before, as I had only used electronic regulators to the field windings of an alternator with a DC field and not pulsed alternators.... Live and learn.....

Anyway, if the voltage regulation is critical , an electronic regulator would work far better.

Reply to
Robert

Would it be better to regulate the peak, average or RMS voltage if the load draws non-sinusoidal current?

I became concerned with the peak after a poorly regulated generator burned out the transient voltage suppressors in an outlet strip, in a cloud of purple smoke. jsw

Reply to
Jim Wilkins

Maybe a third cousin, twice removed? :)

Reply to
Michael A. Terrell

A lot of folks replace the battery on English motorcycles with a big cap for the same reasons

Gunner

The methodology of the left has always been:

  1. Lie
  2. Repeat the lie as many times as possible
  3. Have as many people repeat the lie as often as possible
  4. Eventually, the uninformed believe the lie
  5. The lie will then be made into some form oflaw
  6. Then everyone must conform to the lie
Reply to
Gunner

We could always ask Nikola. ^_^

TDD

Reply to
The Daring Dufas

Nah, he's always so tesla...

Reply to
Michael A. Terrell

So caps ARE regulators of sorts? Not just tuning/balancing?

I wonder, if/when I put on this AVR doodad, if the caps should be removed, or left in place.

Reply to
Existential Angst

At least he alternates. ^_^

TDD

Reply to
The Daring Dufas

On Feb 17, 7:04 pm, "Jim Wilkins" wrote: ulator would work far better.

If the output is non-sinusoidal alternating current, it would depend on the use. If equipment is being used that uses the entire waveform, such as a heater, the RMS would be the choice. For a motor, I'm not sure, but I'd go with RMS unless better info is found. If the device is electronic, which uses a peak detector to form a DC for a power supply, the peak would be reasonable.... However, it would be necessary to look at the output waveform to make a really informed choice. For instance, if the output is a square wave the choice would be different from a stepped sinusoid. Note that rotating machinery will put out a sinusoid but many generators today use a speed lower than 3600 rpm and use an inverter to make the frequency controlled output voltage, often a "stepped sinusoid", which has the RMS of the sinusoid AND the peak level of the sinusoid, but synthesized in steps.

Also, if the output is DC or pulsed DC, a capacitor stabilizes the voltage by reducing the ripple, the same function as the battery in an automobile. For this appication a big ass capacitor in parallel with a resistor can, in many cases, take the place of the battery. If a load is always present, the resistor won't be needed. \ Such stabilizing loads are often used in stabilizing the DC system in large RVs if a battery isn't used.

The requirements are different for an AC system. That accounts for some of the different solutions posted here.

Reply to
Robert

Do you have the Meccalte spec sheet, manual etc for the actual generator head? That would be my source for information. Assuming of course that the offered voltage regulator from the company you bought the assembly from is using a M voltage regulator on an M generator.... I would think the cap does need to be removed as the electronic voltage regulator is going to control the winding field instead of relying on the cap. generator?

Reply to
trader4

I asked because I have several small generators that regulate voltage poorly, typically they have to be set around 140V at no load to maintain 105-110V at full load. Unless I'm running one large insensitive load like the washing machine I pass the power through a metered 20A Variac indoors and change its setting as I add or remove loads.

The APC SmartUps I found at a flea market recently looks like it would handle the variations automatically without modifying the generator. They are too expensive new and not common enough used to be a general solution.

Unfortunately I don't know how much overvoltage things will stand without frying them. My house spiked up to 180VAC once from a powerline problem and the lights buzzed loudly. I knew there was an intermittent fault and was monitoring it. It turned out to be a corroded splice in the neutral in the drop from the street. I needed good evidence to convince the power company to replace the meter box and weatherhead.

Reply to
Jim Wilkins

Sorry, Jim, But your wide applications are getting way outside my area of expertise...... I , personally, would use the variac like you are doing, and set each application up as needed. For a general purpose application to do everything for every purpose, tho, I'd probably buy a big generator as used in RVs, or "whole house", and make sure the warranty is paid up..... I doubt that this opinion is of any use to you, but that's the best I can offer.. Good luck...

PS.... As an afterthought, an interested reader might consider your "neutral" problem, and check the tightness of their neutrals in the meter box, as well as the ground wire connection beside the meter box.... It ain't rocket surgery..... The power company doesn't like people going into the meter box to tighten up the terminals... .... to easy to steal power...

Reply to
Robert

The engine governor has nothing to do with the output voltage regulation, really.

With a conventional AC generator, the speed of the engine governs the output frequency. The generator HAS to run at constant speed, usually

1800 rpm, in order to get 60 Hz out of the generator. Change the engine speed, you change the line frequency.

This is why conventional AC generators ALL have a device to regulate the field coil voltage in order to get constant output voltage. Some of these devices are better than others.

The inverter-style generators are different and what makes them such a big advancement is that they allow you to run the engine at different speeds for different loads by decoupling the engine speed and the final output frequency.

--scott

Reply to
Scott Dorsey

As far as I know, every non-inverter generator works this way. How else would you get a stable output voltage with varying loads? It's not like field coil regulation is terribly expensive; it's not a whole lot of current in there.

I never took power lab in school myself and I feel like I missed a big opportunity.

--scott

Reply to
Scott Dorsey

The power company did try that first. The repairman and I cleaned the meter box contact recesses with my collection of needle files and nachinists scrapers. It seemed OK for a while, possibly because we had pulled on the weatherhead connection, then I started to see the lights flash and buzz at around 4:30PM. The line-to-line voltage held steady, it was the neutral that was bouncing around.

I finally tracked it to a tree trunk shadow passing at that time over the aluminum cable coming down the house, causing a brief drop and then rise in its temperature.

Reply to
Jim Wilkins

How to regulate a permanent-magnet generator:

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US 4,885,493 jsw

Reply to
Jim Wilkins

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