Is split-phase AC the same as "regular" AC?

[bdunham7]

4-stroke engines have always needed a camshaft position sensor in order to fire the right spark plug at the right time.

Well, not in the case of dual-ended ignition coils that fire two plugs, one of them being a "waste" spark that occurs on the exhaust stroke. 

But, as IanB points out, firing orders are not just 4 numbers, the whole sequence goes on and on and it doesn't matter where you start.  Also there is the issue that for a typical 4-stroke engine the entire cycle is 720 degrees of crankshaft rotation.  So I don't think there's too much to be gained in the understanding of single and polyphase power systems by comparing to internal combustion engines.

[Zucca]

6 pages on a simple split-phase question. I am surprised.

Thank God it was not a multiple page datasheet, wonder how many interpretations there are in complex stuff.

[Randy222]

So I don't think there's too much to be gained in the understanding of single and polyphase power systems by comparing to internal combustion engines.

Seems what engineers do. "You" talk about electrical phases and soon enough the conversation jumps to something apparently abstract "relative" to the original topic. In this case, 3ph power jumped to 4cyl engine firing order.

[Randy222]

Basically, you would have ...34213421342134213421... going on forever.

4 comes after 3, 2 comes after 4, 1 comes after 2, 3 comes after 1. These are all relative positions in the firing order.

4 also fires after 1 and after 2, but later 4 fires before 1 and before 2. Now that's just crazy.
I wonder what the phase shift looks like on the crank for actual positions 1,2,3,4?

[paul cotter]

When synchronising a generator to the grid there are three possible connections that are valid. Lets call the grid phases ABC and the generator phases abc. To the grid ABC we can connect with abc or bca or cab it makes no difference as these three(abc, bca, cab) have the same rotation as the grid ABC. The actual process of synchronising requires the frequency, phase and voltage to be matched before connection or trouble will ensue.

[IanB]

Basically, you would have ...34213421342134213421... going on forever.

4 comes after 3, 2 comes after 4, 1 comes after 2, 3 comes after 1. These are all relative positions in the firing order.

4 also fires after 1 and after 2, but later 4 fires before 1 and before 2. Now that's just crazy.
I wonder what the phase shift looks like on the crank for actual positions 1,2,3,4?

I think at this point you are just being tiresome and misrepresenting everything written in order to be a troll.

[m k]

6 pages on a simple split-phase question. I am surprised.

Thank God it was not a multiple page datasheet, wonder how many interpretation there are in complex stuff.

Seems that it's finally pretty simple, main voltage is missing.
And only one coil between phases of delta configured distribution.

Here main voltage between phases is ~400V and phase voltage between phase and ground is ~240V.

[bdunham7]

In this case, 3ph power jumped to 4cyl engine firing order.

Maybe a 3-cylinder two-stroke would be a better case? 

[Randy222]

In this case, 3ph power jumped to 4cyl engine firing order.

Maybe a 3-cylinder two-stroke would be a better case? 

Not sure, need to ask Andy Chee. It could be 1-3-2 or 2-1-3 or 3-2-1, or maybe 1-2-3  or 3-2-1   

[themadhippy]

Maybe a 3-cylinder two-stroke would be a better case?

As were discussing phase rotation  surely  it should be the wankel

[Stray Electron]

Maybe a 3-cylinder two-stroke would be a better case?

As were discussing phase rotation  surely  it should be the wankel

   Nah.  Bringing up a wankel engine and how it operates would just confuse most people. A better example would be the 3 cylinder 2 stroke DKW "3=6" engine or the engine used on the Kawasaki Mach 3 motorcycle.

[Andy Chee]

When synchronising a generator to the grid there are three possible connections that are valid. Lets call the grid phases ABC and the generator phases abc. To the grid ABC we can connect with abc or bca or cab it makes no difference as these three(abc, bca, cab) have the same rotation as the grid ABC. The actual process of synchronising requires the frequency, phase and voltage to be matched before connection or trouble will ensue.

You have just described relative phase angle.

Absolute phase angle would require alignment along every 360 degrees as well as 120 degrees.

[jonpaul]

Dangerous Q and A. risk of fire, shock, death.

Suggest the OP find a licensed electrician in their location.

DO NOT USE A FORUM OR AI FOR MAINS VOLTAGE ELECTRICAL PROBLEMS>

See the professional electricians sites and safety like Mike Holt.

Jon

[paulca]

Well, not in the case of dual-ended ignition coils that fire two plugs, one of them being a "waste" spark that occurs on the exhaust stroke. 

I had a 125cc motorbike.  Honda CG125.  It had an "afterburner".  Thats what I called it.  A little plug in the exhaust, meant to 'reburn' the exhaust just as it enters the comparitively O2 rich exhaust chamber.  Any unburnt fuel well over ignition point just needs a little nudge to burn up.  "Clean air system" or some such is the marketing name.

Its also why you see performance cars/race cars etc spitting flames on the overrun.  It means they don't have an afterburner, but are dumping lots of unburnt fuel through a insanely hot exhaust so it self ignites.  Rally turbos used this effect with thunderous popping and banging anti-lags, using the detonation of the unburnt fuel in the exhaust pipe to drive the turbo on the overurn.

[paul cotter]

I would not have thought the small amount of unburnt fuel in the exhaust stream could be ignited but then again this is not my area.
Also would an explosion in the exhaust not drive the turbo backwards?

[SteveThackery]

4-stroke engines have always needed a camshaft position sensor in order to fire the right spark plug at the right time.

Well, not in the case of dual-ended ignition coils that fire two plugs, one of them being a "waste" spark that occurs on the exhaust stroke. 

Yes, that's true - it's a workaround, albeit a successful one.

But, as IanB points out, firing orders are not just 4 numbers, the whole sequence goes on and on and it doesn't matter where you start.  Also there is the issue that for a typical 4-stroke engine the entire cycle is 720 degrees of crankshaft rotation.  So I don't think there's too much to be gained in the understanding of single and polyphase power systems by comparing to internal combustion engines.

I absolutely agree - it's useless as an analogy.

[Someone]

Also would an explosion in the exhaust not drive the turbo backwards?

Correct, bang bang antilag is adding intentional combustion in the exhaust manifold, before the turbo.

I would not have thought the small amount of unburnt fuel in the exhaust stream could be ignited but then again this is not my area.

These designs intentionally add more fuel and/or drop the spark to leave it completely unburnt and ready to go.

[SteveThackery]

Not sure, need to ask Andy Chee. It could be 1-3-2 or 2-1-3 or 3-2-1, or maybe 1-2-3  or 3-2-1   

No - this repeats the mistake made when discussing four cylinder engines. There are only two firing orders for a triple: 1-2-3 or 1-3-2. With a four cylinder (using the standard crankshaft configuration) there also only two firing orders: 1-3-4-2 or 1-2-4-3.

The confusion comes from writing these in a straight line. When they are drawn in a circle it all becomes clear.



Take the left-most diagram: you can start anywhere on the circle, so 1-3-4-2 is the same as 3-4-2-1, 4-2-1-3 and 2-1-3-4. All of those describe the same firing order. The second diagram shows the other commonly used firing order. Note how it is actually the first one reversed.

With triples, assuming a 120-degree crank, the left diagram shows 1-2-3, which is the same as 2-3-1 and 3-1-2. The right-most shows 1-3-2, which is the same as 3-2-1 and 2-1-3. Again, go round the right-most circle anticlockwise and you get the same firing order as the one to its left. Note also that a triple with a 120-degree crank always fires its cylinders in order, from left to right, or from right to left.

[SteveThackery]

I had a 125cc motorbike.  Honda CG125.  It had an "afterburner".  Thats what I called it.  A little plug in the exhaust, meant to 'reburn' the exhaust just as it enters the comparitively O2 rich exhaust chamber.  Any unburnt fuel well over ignition point just needs a little nudge to burn up.  "Clean air system" or some such is the marketing name.

Yes, an exhaust air injection system. When the burn in the combustion chamber has been incomplete, or when the mixture is rich, unburnt hydrocarbons enter the exhaust system. Air injection introduces more oxygen into the exhaust so that the remaining fuel can be combusted, improving emissions. It's mostly used with a catalytic converter.

Its also why you see performance cars/race cars etc spitting flames on the overrun.  It means they don't have an afterburner, but are dumping lots of unburnt fuel through a insanely hot exhaust so it self ignites.  Rally turbos used this effect with thunderous popping and banging anti-lags, using the detonation of the unburnt fuel in the exhaust pipe to drive the turbo on the overurn.

Yes: it's a system for keeping the turbo spinning when on the overrun. It's horrendously wasteful, of course. I believe the current implementations add the fuel and air to the intake as usual, but ignite it very late in the cycle so it's still burning when it is pushed into the exhaust by the ascending piston.

EDIT: Sorry, I see now that I've just repeated what @Someone said.

[m k]

So I don't think there's too much to be gained in the understanding of single and polyphase power systems by comparing to internal combustion engines.

Axle vibration modeling is easier with electric motor.

[langwadt]

Maybe a 3-cylinder two-stroke would be a better case?

As were discussing phase rotation  surely  it should be the wankel

two-stroke two cylinder, with a 180 degree crank no matter what direction it turns the sequence is  ...1-2-1-2-1-2...,
if the crank is 90 degree the sequence is ..--12--12--12... in one direction, ...--21--21--21--21.. in the other direction

[Randy222]

Not sure, need to ask Andy Chee. It could be 1-3-2 or 2-1-3 or 3-2-1, or maybe 1-2-3  or 3-2-1   

No - this repeats the mistake made when discussing four cylinder engines. There are only two firing orders for a triple: 1-2-3 or 1-3-2. With a four cylinder (using the standard crankshaft configuration) there also only two firing orders: 1-3-4-2 or 1-2-4-3.

The confusion comes from writing these in a straight line. When they are drawn in a circle it all becomes clear.

(Attachment Link)

Take the left-most diagram: you can start anywhere on the circle, so 1-3-4-2 is the same as 3-4-2-1, 4-2-1-3 and 2-1-3-4. All of those describe the same firing order. The second diagram shows the other commonly used firing order. Note how it is actually the first one reversed.

With triples, assuming a 120-degree crank, the left diagram shows 1-2-3, which is the same as 2-3-1 and 3-1-2. The right-most shows 1-3-2, which is the same as 3-2-1 and 2-1-3. Again, go round the right-most circle anticlockwise and you get the same firing order as the one to its left. Note also that a triple with a 120-degree crank always fires its cylinders in order, from left to right, or from right to left.

Does the arrow change if the motor starts with a kickstart that kicks down to front vs down to rear? Or does the OEM just change numbering of the ink in manual?

[Stray Electron]

Well, not in the case of dual-ended ignition coils that fire two plugs, one of them being a "waste" spark that occurs on the exhaust stroke. 

I had a 125cc motorbike.  Honda CG125.  It had an "afterburner".  Thats what I called it.  A little plug in the exhaust, meant to 'reburn' the exhaust just as it enters the comparitively O2 rich exhaust chamber.  Any unburnt fuel well over ignition point just needs a little nudge to burn up.  "Clean air system" or some such is the marketing name.

Its also why you see performance cars/race cars etc spitting flames on the overrun.  It means they don't have an afterburner, but are dumping lots of unburnt fuel through a insanely hot exhaust so it self ignites.  Rally turbos used this effect with thunderous popping and banging anti-lags, using the detonation of the unburnt fuel in the exhaust pipe to drive the turbo on the overurn.

  In rockets it's been known for a long time that the high temperature exhaust from a stoichiometric fuel ratio can act as a very powerful oxidizer or fuel.  So its a common practice to burn extra fuel to lower the molecular weight of the exhaust without lowering the flame temperature so that the exhaust will have a higher expansion ratio and thus produce most thrust.  Prior to emissions controls the same thing was done in automobile engines so the exhaust was also slightly fuel rich.  The air injection pumps on the automobile exhaust system and tricks like Paulca is talking about were an early attempt to reduce the (excess) hydro carbon emissions of carbureted automobile engines. Once computer controlled fuel injection replaced carburetors such things were no longer needed

[Obsidianxenon]

So I still not following your relative comment.

Not sure if this would help but think about the output of a function generator. A single-output function generator has no phase control. Why? Because altering the phase of the output is meaningless without a second output or reference. What advantage would it hold anyway if you could delay the output by some microseconds? The phase relative to, say, an input reference could be defined, but if the output frequency was different to that reference then it would vary as a function of time.

Another way of thinking about it is the same way we think about voltage. You can't have an absolute voltage because by definition it is a difference in electrical potential between two points. A singular point in of itself has no voltage because both of your probes would be on the same point, measuring a difference of zero. Zero volts. Same goes for phase. You need to measure between different signals (or the same signal at different points in time) to be able to have any measurement of phase shift. Absolute phase is a contradiction of its meaning.

[paulca]

Also would an explosion in the exhaust not drive the turbo backwards?

Correct, bang bang antilag is adding intentional combustion in the exhaust manifold, before the turbo.

I would not have thought the small amount of unburnt fuel in the exhaust stream could be ignited but then again this is not my area.

These designs intentionally add more fuel and/or drop the spark to leave it completely unburnt and ready to go.

https://youtu.be/rmf0LveXwVk
https://youtu.be/YvgaBWNjrFA

When a rally car is coming, all you hear is "BANG,clatter, clatter ,BANG" and it still half a mile away.

Every time the throttle is lifted, instead of "Dump valving" the over pressure on the turbo, they do the opposite, they inject unburnt fuel into the exhaust and ignite it to detonate and keep pushing high pressure exhaust through the turbo.  This allows they to run HUGE turbos with HUGE lag, but as the anti-lag fires constantly the moment they take the foot off the throttle, it's still spinning at full speed on the corner exit ready to apply full power.

On the start line, they hold it on a launch rev point.  The anti-lag is running nearly constantly not quite full BANG, but a constnat machine gun of them.

The purpose of the 3-5 seconds like this is to spin the turbo up to full RPM before they leave the line with FULL boost instantly.

EDIT:  It should be noted that this practice came under a lot of scrutiny.  Ford used a large cylinder in the exhaust system and added valves to it.  Then they charged the cylinder up with exhaust and used it to run the turbo.  It was promptly banned.

However modern rally cars don't BANG and rattle.  They chirp and crackle.  Im not sure how they tamed it, possibly by making the detonation much more controlled and engineered rather than something worked out in a shed by a farmer once upon a time.