Stator vs Rotor Amp Question
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From: poway
electrical generation and electrical load are diff.
while true, because of the neutral the wye only has 1/3 of the power on each leg it effects a motor in profound ways, lose a leg, you lose 1/3+ in motor output if you factor in parasitic loading. you could lose a leg on delta and if the other two legs can handle the load the motor will function fine.
remember, the hd wye joins at the regulator so each leg cumulative to the dc output. remember there is NO three phase loads on the machine.
as far as the shovel system used for maybe 2 years it was superior to the pmg in a lot of ways. it was an alternator which means there was variable excitation to match load. a pmg cannot do this, it will start falling on its face.
i did not state it was better than a 3 phase hd now uses. all i was saying that hd could have developed it further. the pmg on an hd is designed to be used in a certain rpm range, much shorter than an alternator.
in a way, the generator was superior because it was actually an ac machine, just would have been too bulky to use further. now there was some bleed to ground but NOT as what people think or say. just like a diode, an open contact can not conduct, it is one way like the current in the diode. the bleed was there to make there regulator work. the system was a balance of mechanical and electro-mechanical forces.
people say the pmg on hd bleeds all unused current to ground, NOT. there were several regulator systems used but all have one thing in common, if the semiconductor is not biased on then there is NO current.
as far as the jump pack, most use a doubler or tripler circuit. a few c cell size batteries cannot sustain a voltage that high for long. the voltage is the EMF or diff'l that causes the circuit to start flowing. once flowing, the voltage level is of a lesser concern. you can look at it as a start/run capacitor system.
on the starter, if you lock the rotor, current is determined by the resistive load of the winding. there is a love/hate relationship. why the high inrush??? well factor in counter EMF which the winding see as a resistive load so when the voltage takes a large tumble the amperage with rise. but remember this is a temp thing because as the starter gains rpm, counter EMF wanes.
while true, because of the neutral the wye only has 1/3 of the power on each leg it effects a motor in profound ways, lose a leg, you lose 1/3+ in motor output if you factor in parasitic loading. you could lose a leg on delta and if the other two legs can handle the load the motor will function fine.
remember, the hd wye joins at the regulator so each leg cumulative to the dc output. remember there is NO three phase loads on the machine.
as far as the shovel system used for maybe 2 years it was superior to the pmg in a lot of ways. it was an alternator which means there was variable excitation to match load. a pmg cannot do this, it will start falling on its face.
i did not state it was better than a 3 phase hd now uses. all i was saying that hd could have developed it further. the pmg on an hd is designed to be used in a certain rpm range, much shorter than an alternator.
in a way, the generator was superior because it was actually an ac machine, just would have been too bulky to use further. now there was some bleed to ground but NOT as what people think or say. just like a diode, an open contact can not conduct, it is one way like the current in the diode. the bleed was there to make there regulator work. the system was a balance of mechanical and electro-mechanical forces.
people say the pmg on hd bleeds all unused current to ground, NOT. there were several regulator systems used but all have one thing in common, if the semiconductor is not biased on then there is NO current.
as far as the jump pack, most use a doubler or tripler circuit. a few c cell size batteries cannot sustain a voltage that high for long. the voltage is the EMF or diff'l that causes the circuit to start flowing. once flowing, the voltage level is of a lesser concern. you can look at it as a start/run capacitor system.
on the starter, if you lock the rotor, current is determined by the resistive load of the winding. there is a love/hate relationship. why the high inrush??? well factor in counter EMF which the winding see as a resistive load so when the voltage takes a large tumble the amperage with rise. but remember this is a temp thing because as the starter gains rpm, counter EMF wanes.
What is PMG? Permanent magnet generator? The older DC systems weren't. They were field actuated. They did relay on some residual magnetism in the field pile metal.. One of the reasons why you have to polarize the generator.
The problem with generators is maintenance and cost to build. They are less efficient. Also you can make an alternator flatter axially.
Here PMG sounds like PMA. HD alternators don't short to ground. If they short anything, they short a phase.
I would think that jump pack use 4 LI batteries to get 13.2 volts. Yes they are C cell sized diameter wise but are a bit longer. The thing about them is that they can put out a bunch of current but only for a short period of time..
BTW, the pic below is the shovel charging system.
Not sure how you can say " it was an alternator which means there was variable excitation to match load." IIRC this was used until 76. FWIW Higher end Jap bike used excited field coils. Honda used a clever way to eliminate field brushes where the others used them. If HD Shovels were using permanent magnet rotors starting in 76, I think that most Jap bikes were still using field coils.
The extra coil looks like a shunt coil triggered by an SCR. It triggers as the voltage rises so I'd guess that it's dropping current.
I've always figured the inrush current wasn't back emf but the fact that it take a lot of current to get the motor spinning and that causes the counter EMF? Not sure how the counter emf talk about wanes unless the counter EMF only occurs when the starter is under load.
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i am using generalities, not specifics. battery size is just one example.
the issue with the generator would be size. the brush/segment relationship converted the ac to dc.
there was two systems in the ole shovel, a main and an aux. the aux was controlled by a special regulator (hard to find now) that excited the main.
YES, rice was wayyyyyy ahead and eventually hd took note but however, they were still left in the dust.
can wye be used without a neutral, why sure!! you just cannot directly supply a 120v line. in this case, often a ground is used but not as a current carrying wire. look at a 230v table saw, two current carrying and no neutral but a ground, mostly as a safety as it helps trip a circuit protection devise.
utilities often feed transformers without carrying the neutral.
the pmg is a great devise since it is self generating but has its limits, not better than an alternator.
the hd generator had shoes that had coils that the regulator used to increase output. they did hold residual magnetism and some times lost it, the reason why you had to flash them to restore residual to the shoes. note that the regulator did NO conversion. as stated, some current was shunted to ground, used to make the regulator work, look on the back of one and you will see the resistor. if you reverse bias the the regulator, it will smoke that resistor, BUT more importantly, the generator will produce current either way but reversed to the regulator, it cause the point to vibrate violently and burn them up. NOW before the panties get into a wad, there were negative and positive regulators, the positive used more so over seas.
as far as rice, i used to run a tricked out 305 that would keep within 2>3 bike lengths to a 750-4 to about 90mph where the 305 pretty much topped out due to gearing, was a street hopper. i used a 12dc dry cell to kick off the ignition but it ran off the pmg. without that dry cell, if you had someone to push it, the pmg would fire the ignition.
BTW: this is a jpeg of a project done several moons back, converted the xl generator to a pmg. the armature windings replaced with magnets and a coil form holder pressed into the body. the project is up on another forum. a couple short youtube videos exist also.
the issue with the generator would be size. the brush/segment relationship converted the ac to dc.
there was two systems in the ole shovel, a main and an aux. the aux was controlled by a special regulator (hard to find now) that excited the main.
YES, rice was wayyyyyy ahead and eventually hd took note but however, they were still left in the dust.
can wye be used without a neutral, why sure!! you just cannot directly supply a 120v line. in this case, often a ground is used but not as a current carrying wire. look at a 230v table saw, two current carrying and no neutral but a ground, mostly as a safety as it helps trip a circuit protection devise.
utilities often feed transformers without carrying the neutral.
the pmg is a great devise since it is self generating but has its limits, not better than an alternator.
the hd generator had shoes that had coils that the regulator used to increase output. they did hold residual magnetism and some times lost it, the reason why you had to flash them to restore residual to the shoes. note that the regulator did NO conversion. as stated, some current was shunted to ground, used to make the regulator work, look on the back of one and you will see the resistor. if you reverse bias the the regulator, it will smoke that resistor, BUT more importantly, the generator will produce current either way but reversed to the regulator, it cause the point to vibrate violently and burn them up. NOW before the panties get into a wad, there were negative and positive regulators, the positive used more so over seas.
as far as rice, i used to run a tricked out 305 that would keep within 2>3 bike lengths to a 750-4 to about 90mph where the 305 pretty much topped out due to gearing, was a street hopper. i used a 12dc dry cell to kick off the ignition but it ran off the pmg. without that dry cell, if you had someone to push it, the pmg would fire the ignition.
BTW: this is a jpeg of a project done several moons back, converted the xl generator to a pmg. the armature windings replaced with magnets and a coil form holder pressed into the body. the project is up on another forum. a couple short youtube videos exist also.
Last edited by bustert; Jan 19, 2025 at 08:41 AM.
Seasoned HDF Member
Joined: Dec 2005
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From: poway
Absolutely a single Y phase can be used without the neutral. I was saying simply more power can be had if there is one..
In the case you mention, isn't a PMG really a permanent magnet alternator?
In the case you mention, isn't a PMG really a permanent magnet alternator?
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