Electricity; Just Playing

[boscoe99]

Not exactly sure what you are trying to prove or "myth bust" but, output voltage with no load means very little, please explain what your experiment is attempting to achieve.

Not trying to prove or myth bust anything. How did you come to that conclusion?

Absolutely no load voltage means very little. Actually, no load voltage means nothing other than the fact that a voltage is being developed.

Voltage and load (current) equate to electrical power. P = V * I. If I is 0 then P = 0.

[99yam40]

well how did things go this morning?
or did you not play with it yet?

[boscoe99]

I have been cleaning gutters, putting down 25 bales of pine straw and 1 cubic yard of mulch today. In advance of coming rain. Have not played further.

To answer some of your questions the output leads of the rectifier are shorted to each other to determine maximum current flow. Which is a function of the rotor speed. TBD.

Some of the companies that sell them offer the maximum current flow specs. Some don't.

I got one that is rated for high speed. They come built for different applications. Or you can buy just a rotor and install it in an old alternator bought at a junkyard for about five bucks.

The windings in the housing can be built for maximum current and low voltage or high voltage and low current. If nothing else I am getting an un-needed education in PMAs for off grid usage. Have learned more than I would have about the inner workings of rectifier/regulators as well. For both PMA and conventional AC generators.

[zenoahphobic]

Similarly like voltage output with no load, shorting the output current means nothing.

One needs a purpose in generating electricity, and that usually means to met some voltage, and in alternating current frequency, goal.

In the situation of a short, the electricity is consumed within the generator windings, meaning that the generator has "zero" efficiency. I would think efficiency is related to output resistance divided by internal resistance. That is the greater the load resistance, the greater the efficiency.

It follows then you will get the more power the higher the voltage output, compared to zero voltage output in the case of shorting the output.

[boscoe99]

well how did things go this morning?
or did you not play with it yet?

Just measured the maximum current output with the PMA turning 1596 RPM. 34 amps. Next step will be to load the PMA to determine what current will take the voltage down to ~ 14.6 volts.

Given that the Yamaha power curve for a R/R is not linear I expect to see the same thing in this PMA. There are some high falutin names for why it is not linear but I can't remember them.

[99yam40]

how will you vary the loading?

We use to use load banks of resisters or large 1500 what light bulbs on our rectifiers during testing.
not for max load but just to put a load on them . And no way to vary load exept putting more bulbs or resister in to the system
they were about 800 V dc output and normal load was 70 to 80 K amps, but just testing diode units and also thyriseter run units.
I was just a grunt doing the regular electrical maintenance at the plant and helped with testing.
EEs just told me what to do and when

[rodbolt17]

70,000 amps?
I call BS

[99yam40]

70,000 amps?
I call BS

Oh it is true
Large chemical plant that produced clorine buy running DC threw brine.
also had units in the mag plants.
these units were started back during WWII to produce magnesium.
I even had switchgear made back in the 40s I took care of.
the Mag plants would parallel outputs and run loads up to 170KA thru a molten salt bath to produce the metal

inputs were 15KV and 138KV into either regulating transformers and then to retifier transformers on the old diode rectifiers or straight into the rectiformer on thyristor units.

They even came up with some chopper units that I never understood very well.
just a way to control the DC output. 1st time they turned them on the rebar in the flooring around where the bus bar went thru overheated from induction heating

You should have seen what would happen when something faulted.
heavy bus bars would bend & bust insulators holding and supporting it from the magnetic repulsion of the + and - during the fault

[fairdeal]

I'm looking forward to learning your results when you get the Yamaha regulator connected.

while I "know" that it is a "shunt type" - I really understand nothing about how it works
and I have a nagging doubt that "maximum current" is actually always flowing..

(for one thing,
why is the r/r ground wire(s) gauge typically significantly smaller than the output wires?)

[boscoe99]

Fairdeal if you are interested I can email you some data on this stuff.

From what I have seen in Yamaha data and on the innerweb, all of the shunting to control the voltage is done internally.

So far I can see full output voltage with no current flow. I can then see full current flow with the rectifier output leads shorted directly to each other. I can see that as an external load is applied (hair dryer and coal starter element in my test case) the voltage drops. As a function of the amount of the load. The regulator is doing automatically a billion times a second what I am doing manually.

What I need to measure is the AC power output with the rectifier shorted. Correlate it with the DC power output from the rectifier. Then with the Yamaha R/R connected see if the AC power output from the PMA is the same.

Capiche? Am I on the right track or do I need some course adjustment?

[fairdeal]

I need to put some effort into thinking about it, to make any useful suggestion.

but I do know, what interests me most,

how does the "workload" - the HP being used to drive against the magnetic force - compare:

- when maximum amps are "leaving the r/r" as output (however they then return to ground)
vs
- when, at the same RPM, little to no output is "leaving the r/r" - but is instead "shunted"

My suspicion is that is does not require as much "work" when the alternator is being "shunted" -
but I have no more support for that than a "feeling"...

[boscoe99]

Maximum AC current from each of the three AC input leads is 24 amps with the rectifier DC output leads shorted together. Maximum current output from the rectifier is 34 DC amps with the output leads shorted together. Rectifier output voltage is below 1 volt.

With the Yamaha rectifier/regulator connected instead of the rectifier, the output voltage is ~ 15. No load connected to the DC output leads from the R/R. The AC current to the Yamaha R/R remains at 24 amps in each of the three leads.

Does this mean that all of the electrical power is being dissipated within the R/R?

[99yam40]

I was typing and thinking while you typed your last post, so I would say yes open RR output means all Power is being Shunted(dissipated) in the RR.
The RR is trying its best to bring that voltage down , Since there is no power being sent out of the RR just 15 v then all of the current being produced has to be sent somewhere. Did you measure AC voltages also in the open RR test?



You answered some of my questions already but maybe you can answer some of the others


Has any current reading been measured on the AC and DC so far, along with the AC & DC voltages?
Open & Shorted RR and with the resistive element loads?

need to keep records of all of that as you go, so you can look back and study them and come up with more testing.

Are you using a DC shunt and MM to get DC current?
Or maybe a DC clamp on meter?
AC is simple enough with a clamp on or CT( current transformer) and MM, but not sure you have a DC clamp on .

Would not the RR shunt off voltage(and Current) to keep the voltage withing spec even when the RR out put was open(not shorted)?

Any heating elements should work for a load. something from a electric clothes drier or home heating duct type. Ni-chrome wire in coils. they are just resisters.Just need to be supported and not touching something that will burn.
might be able to vary load by moving one connector to different places along the heating element( maybe a alligator clip would hold up for short runs)
I believe a problem with those heating elements is the resistance changes some as they heat up, if you are trying to keep track of Ohms law

[fairdeal]

Maximum AC current from each of the three AC input leads is 24 amps with the rectifier DC output leads shorted together.

With the Yamaha rectifier/regulator connected instead of the rectifier, the output voltage is ~ 15. No load connected to the DC output leads from the R/R. The AC current to the Yamaha R/R remains at 24 amps in each of the three leads.

So the full available amount of amps DOES "go into" the R/R - even though nothing "comes out".

This is fascinating; so many mysteries.

If all of the current, is already being "dissipated", why does any of it flow out when a "real" load is connected" ?

[99yam40]

A normal battery system the battery will load up the system and drop the voltage down so the current flows into the battery, once it charges up the battery voltage goes up so it takes less of the current. excess voltage and current(power being produced has to go somewhere). only the voltage above the set point(15V) should flow to ground at the RR
It has to shunt off to ground, that is what causes all the heat and burns things up from time to time
I really do not know how the Yamaha RR works electronically, maybe Rodbolt could fill us in.

a normal AC transformer needs for current to flow in the secondary for flow to happen in the primary