Could a sh775 kill a stator?

[Gorminrider]

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Assume the short is a simple resistor with about 0.05 ohms

. I get that it can ideally be, but if not, it might be just something less than 6 ohms . Somewhere around full-conduction there are halfway stages that are making them hot. Why else invent a mosfet type? Your model of 0.05 ohms suggests that as your stator burns, a shunt type regulator is colder than the wires attaching it- not impossible; connections ARE often cited- (see 850combat's post?) but anecdotally, how many replace the stator while the R/R is perfectly fine? I think not many. They seem to fail as a pair, or the R/R fails first...
anyways, I've got to get back to the rocket I was building

[posplayr]

[ATTACH=CONFIG]48487[/ATTACH]I am thinking of this...but part of my analysis would involve placing a finger on the heatsink of an operating shunt R/R

That is the same thing, I'm just showing a simplified R/R but expanded stator equivalent circuit.When the R/R shorts nothing goes to the battery.Of course there is still current flow in the 3rd phase but it is all unbalanced. Look at the way the current curve is bouncing around with several different harmonics/frequencies/.

Rule of thumb (V=IxR); if finite current is flowing there is voltage.

[Gorminrider]

rectifier_scheme.jpgI am thinking of this...but part of my analysis would involve placing a finger on the heatsink of an operating shunt R/R

[posplayr]

Well no, my kindergarten electronics don't see it that way when the shunt is the only load in the circuit ...It must have a higher vdc.



Simplistically,and with wild assumptions as to proportion, Pretend the ground potential is 14vdc and the shunt is shunting ALL the stators output.
My idea says the RR portion is say 6vdc@15 amps. Thats 90 watts consumed. (The stator's would be 8vdc@15amps) That would be warm to the touch with a pretty good heatsink !
Your idea seems to say the RR portion is 0.5vdc@15 amps. That's 9 watts. I can't think of much that could ever burn out with 9 watts if it was encased in an aluminum heat sink. I don't think it could be felt with a touch.

of course amperage varies per stator and what loads are also on the bike...headlight, battery charging etc etc

Sorry, I'm not even going to address you analysis without a schematic.

You apparently don't want to take my word for it, so I suggest you actually look a circuit diagram of the stator(see one below). For example each stator leg is a AC source ,with series resistance and inductance. There are three AC sources all 120 degree out of phase.

When you short two of those phases together you have a circuit of 6 elements (2AC source, 2 resistors, and two indicators) all in series. Assume the short is a simple resistor with about 0.05 ohms.

You know the DC resistance of the stator from the factory manual, and you can estimate the reactance of the inductance from the phase angle when not regulating.

This might help you understand why current keeps flowing in the stator despite the shorted R/R. You can see according to 1st principles of circuits, the two legs have to be equal and opposite by symmetry. If they are non zero then the neutral moves from ground and current keeps flowing driven by the two AC sources in each leg.

https://en.wikipedia.org/wiki/Kirchhoff's_circuit_laws

his law is also called Kirchhoff's second law, Kirchhoff's loop (or mesh) rule, and Kirchhoff's second rule.
The principle of conservation of energy implies that
The directed sum of the electrical potential differences (voltage) around any closed network is zero, or:More simply, the sum of the emfs in any closed loop is equivalent to the sum of the potential drops in that loop, or:The algebraic sum of the products of the resistances of the conductors and the currents in them in a closed loop is equal to the total emf available in that loop.

[Gorminrider]

The light blue is the current(see the legend).There is no place where the current has a vertical segment terminating or starting from zero.

I must be misreading it. I don't find it easy. Ideally it should be 0 according to the general take on series regulation . I assume this pdf attempts to show how it works in detail. Nothing is perfect... the blue line squiggles above and below the line. It is 0 whenever it does and the average is near enough 0 ...coincidentally when the yellow voltage line does take a nearly square" hike".
But I will go back to my first impression... "ringing" on cutoff.

[posplayr]

here...[ATTACH=CONFIG]48473[/ATTACH] and yes I did assume V would have to be theoretically infinite but in real life with wire in a field I expect it doesn't really happen.

The light blue is the current(see the legend).There is no place where the current has a vertical segment terminating or starting from zero.

[Gorminrider]

The voltage regulator is the short and yes that short might be a small voltage (less than 0.5V) but that is why the R/R gets hot

Well no, my kindergarten electronics don't see it that way when the shunt is the only load in the circuit ...It must have a higher vdc.



Simplistically,and with wild assumptions as to proportion, Pretend the ground potential is 14vdc and the shunt is shunting ALL the stators output.
My idea says the RR portion is say 6vdc@15 amps. Thats 90 watts consumed. (The stator's would be 8vdc@15amps) That would be warm to the touch with a pretty good heatsink !
Your idea seems to say the RR portion is 0.5vdc@15 amps. That's 9 watts. I can't think of much that could ever burn out with 9 watts if it was encased in an aluminum heat sink. I don't think it could be felt with a touch.

of course amperage varies per stator and what loads are also on the bike...headlight, battery charging etc etc

You guys get that rocket built yet?

[Gorminrider]

Current can't stop instantly, if it did V = L dI/dt (time derivative), voltage, would have to be infinite. ; where did you see that?

here...posSSRgraph.jpg and yes I did assume V would have to be theoretically infinite but in real life with wire in a field I expect it doesn't really happen.

[posplayr]

posplayer-yes, I had to go off and think about that but,I was wondering per the 0 current from your pdf (ssr_VS fh012aa) where it shows the current drops instantly to 0..., it does this because...

I didn't know they did that though it's plain enough from your pdf, now you mention it.

I don't see where the "collapsing field" goes( but come to think on it) it is much weaker than I am thinking because , there aren't really enough windings to produce a powerful spike are there?- and is simply cancelled/merged ... I was supposing that was the spike I see in your pdfs but apparently not....

but isn't there a voltage drop across the regulator? across all these "semiconductors?" a bit more than 1/2 a volt I figure each one to be when charging or applied to the bikes demands... concurrent so to speak with the shunting, ( a separate stage from rectification as I understand it from diagrams I have ? ) so it has to be a larger portion of total DC Voltage, not just the half volt mentioned in rectification...with the other portion being across the stator..

actually, this very experiment IS on my list.. I will sooner or later get a spare not-too-bad one and finish it off this way! I guess I'll have to, to be "satisfied".

Yes! I read that with interest. I am seriously toying with the idea that a large heatsink on the casing might help if it didn't interfere with my gearshift!

Current can't stop instantly, if it did V = L dI/dt (time derivative), voltage, would have to be infinite. ; where did you see that?

AC current cycles go through zero twice per cycle. If you open the loop at zero current there is no voltage spike.

The voltage regulator is the short and yes that short might be a small voltage (less than 0.5V) but that is why the R/R gets hot.

Each stator leg, in 120 degrees of succession, generates it's AC waveform( due to mechanical phasing of rotor magnets and the stator poles). Just because you tie two legs of the stator together does not stop the current (look at the current measurements while the MOSFET SHUNT FH012AA R/R is shorted) in either leg and does not mean there is zero voltage across either leg. The sum of the legs is zero(of the voltage in the R/R short), but not each individually. Assuming a Wye configuration, during the short that floating neutral is nowhere near ground anymore.

If you measured Leg to neutral to would not see zero on any leg if there is current flowing. You would need to solder a wire to this point to be able to make this measurement.

As the engine rotates, a portion of that mechanical power is converted to electrical power through the PM alternator. This assumes there is current flowing. If you open the circuit, then there is no current flow and there is no power lost/generated. You allow current to flow and there is power conversion and the stator and the R/R get warm due to the resistive components of their respective reactant.

[Gorminrider]

posplayer-yes, I had to go off and think about that but,I was wondering per the 0 current from your pdf (ssr_VS fh012aa) where it shows the current drops instantly to 0..., it does this because...

The SERIES regulation strategy uses something called Synchronous rectification, which means that it operates in sync with the AC waveform. The frequency changes with RPM so it needs to keep track of that RPM and phase of the AC waveforms.

I didn't know they did that though it's plain enough from your pdf, now you mention it.

I don't see where the "collapsing field" goes( but come to think on it) it is much weaker than I am thinking because , there aren't really enough windings to produce a powerful spike are there?- and is simply cancelled/merged ... I was supposing that was the spike I see in your pdfs but apparently not....

And yes the SHUNT type R/R literally shorts the stator legs(with an SCR or MOSFET depending on which is being used)

but isn't there a voltage drop across the regulator? across all these "semiconductors?" a bit more than 1/2 a volt I figure each one to be when charging or applied to the bikes demands... concurrent so to speak with the shunting, ( a separate stage from rectification as I understand it from diagrams I have ? ) so it has to be a larger portion of total DC Voltage, not just the half volt mentioned in rectification...with the other portion being across the stator..

If you want to try it, short all three stator legs together and take a ride on your bike. You will fry the stator.

actually, this very experiment IS on my list.. I will sooner or later get a spare not-too-bad one and finish it off this way! I guess I'll have to, to be "satisfied".

I know that putting a oil sprayer onto the stator reduced engine oil temperature in my 1166.

Yes! I read that with interest. I am seriously toying with the idea that a large heatsink on the casing might help if it didn't interfere with my gearshift!

[posplayr]

http://www.thegsresources.com/_forum...27#post2349127



Well, to me it's not a no-brainer. I just vaguely remember reading my audels book and I skipped the hard bits but I've a vague troubleI have with the series-type R/R's... collapsing fields . Everytime the "circuit" opens the counter-field generated by the current produced cutting flux collapses- just a bit like an ignition coil...(and I am not the expert to judge the consequence of this-something about eddies and such producing heat in the armatures...? but you can see the voltage spikes in posplayers pdf. They have to go somewhere. You can't cut off power to a coil without consquence....

Per the shunt-type, it seems to me they are not "short circuited".because the stator itself has no circuit except through the R/R. . The shunting R/R is "the load". I imagine a lightbulb replacing it.... Will my stator burn out in this scenario? Taken alone, It should not....So,why do some R/Rs burn out? The speed at which they turn off and on is part of it(especially the old ones) and so...FETs versus a plain SCR which I guess tends to get stuck half way through full conduction by the rapid cycling and thereby heats up too much.... But it's true the stator is "producing" and has resistance(inductance) in it's windings as part of the circuit...it just gets sooo complicated to add the heating in the armature itself, eddy currents and the actual engine heat from the nearby 40-90 hp mill it's attached to...(that mill is the largest heater in the area and deserves a little more "credit" I think )

But against my misgivings and my guesses are all your experiences and maybe I'll get one too, down the road.

The SERIES regulation strategy uses something called Synchronous rectification, which means that it operates in sync with the AC waveform. The frequency changes with RPM so it needs to keep track of that RPM and phase of the AC waveforms.

The current is also AC and you will notice that in most of the plots of the Compufire, the current is switched off at zero crossings of the current minimizing any L dI/dt (inductive) transients because a switch from zero amps(closed loop) to zero amps(open loop) has an dI/dt=0.

The voltage goes way up because it is open loop but it is also associated with zero current. When the switches are closed (through the dynamic rectification process) the stator output is tied to the battery voltage which tends to limit how high the stator voltage can go.

And yes the SHUNT type R/R literally shorts the stator legs(with an SCR or MOSFET depending on which is being used) . If you want to try it, short all three stator legs together and take a ride on your bike. You will fry the stator.

You could do the same thing with you house wiring, stick a penny into the fuse box, so it wont blow and short out one of your house outlets. The wires in the house will fry.

The things that most people miss is that the PM alternator is a essentially a constant AC current source once you get over say 3K RPM.
The power dissipated in the statro is based on Ohms law P=I^2xR . It is entirely possible that if there are enough conductive cooling paths , and oil to keep the statro in thermal equilibrium then you will get a relatively constant heat output from the stator.

But here is the rub, if the temperature of the stator, rises so to does the resistance of the wire in the stator and so it produces more power which makes it hotter which increase the temperature still further. It is basically an unstable process limited only by the engines ability to absorb and expel that heat.
I think this is teh primary reason for teh separation in experience that people have. People with big CC bikes that ride them hard burn up stator , like people with small CC bikes that run then flat out all the time do as well.

Some people with 750/850 that ride more reserved are probably the ones with the best stator reliability using SHUNT r/r's.

I know that putting a oil sprayer onto the stator reduced engine oil temperature in my 1166.

[Gorminrider]

http://www.thegsresources.com/_forum/showthread.php?243915-Could-a-sh775-kill-a-stator&p=2349127#post2349127

From what I understand, the regulation used in the SH775 works by triggering SCR diodes at the correct phase angle, until then the stator windings will be left open – as opposed to shunt, where the windings will be essentially short-circuited.

Well, to me it's not a no-brainer. I just vaguely remember reading my audels book and I skipped the hard bits but I've a vague troubleI have with the series-type R/R's... collapsing fields . Everytime the "circuit" opens the counter-field generated by the current produced cutting flux collapses- just a bit like an ignition coil...(and I am not the expert to judge the consequence of this-something about eddies and such producing heat in the armatures...? but you can see the voltage spikes in posplayers pdf. They have to go somewhere. You can't cut off power to a coil without consquence....

Per the shunt-type, it seems to me they are not "short circuited".because the stator itself has no circuit except through the R/R. . The shunting R/R is "the load". I imagine a lightbulb replacing it.... Will my stator burn out in this scenario? Taken alone, It should not....So,why do some R/Rs burn out? The speed at which they turn off and on is part of it(especially the old ones) and so...FETs versus a plain SCR which I guess tends to get stuck half way through full conduction by the rapid cycling and thereby heats up too much.... But it's true the stator is "producing" and has resistance(inductance) in it's windings as part of the circuit...it just gets sooo complicated to add the heating in the armature itself, eddy currents and the actual engine heat from the nearby 40-90 hp mill it's attached to...(that mill is the largest heater in the area and deserves a little more "credit" I think )

But against my misgivings and my guesses are all your experiences and maybe I'll get one too, down the road.

[tom203]

It is pretty clear he is a troll seeking attention. ...

yes, probably recently lost his job spamming for the clinton campaign- needs new outlet for his hostility.

[cowboyup3371]

There's plenty of hearsay and "empirical evidence" on this forum . Do you want his brother to certify himself as a Polaris "service writer" to post the same thing?. I can't imagine why DohcBikes makes this up. It is what is for what it is worth. however, WILL get you into a discussiont and maybe that's what is wanting more..

He has made a claim they are worse than any other yet hasn't backed it up with proof. Posplayer backed up his initial claims about the SH775 a few years ago with both the high-level expert stuff and actual proof through riding. After several others on this forum supported Posplayer's claims through their own actual experience as written here, more began to use the product and provided proof as to its effectiveness. I personally have seen how well the SH775 works through my own actual experience enough to the point I bought one for my daughter.

Where is his proof to support his claims? Where are the links to the service bulletins or actual reviews of the product failing MORE than a shunt series? He needs to give us something more than wild claims that will refute what many of us already know is true based on our actual experiences.