Just curious. ( 3phase alternator)

[Allan k]

I'm trying to understand the electrical system on the triples. My 550 runs a 3 phase alternator ( the 4th must be ground? But why 3 phase? These 3 runs to the recifier to be converted to DC. + current in the orange wire, and negative in the ground. Correct?

The rotating part of the alternator has two brushes, with + and - from batteri to make a magnetic field, correct?

Is this type of alternator the opposite of the 'constant magnetic' unit found on other bikes? Wich does not require power to make power?

Why did they choose this type for our sukis?

As discussed in another topic here on the forum. I'm thinking of improving the ignition system on my 550, using a relay for the coils, providing them with current directly from battery. What relay would you recommend for this?

[Alan H]

I'm trying to understand the electrical system on the triples. My 550 runs a 3 phase alternator ( the 4th must be ground? But why 3 phase? These 3 runs to the recifier to be converted to DC. + current in the orange wire, and negative in the ground. Correct?

No. the three phase goes to the rectifier, that's why there's 6 diodes. No earth until after the rectifier.
The rectifier converts the 3 phase AC to DC to charge the battery. The rectifier is earthed which makes the charging circuit.

The rotating part of the alternator has two brushes, with + and - from batteri to make a magnetic field, correct?

Yes. The regulator operates to change the current to this to change the amount of power coming out of the alternator. When battery voltage is low you get more output, when the battery is charged, you need (and get) less output. A properly set up regulator won't boil the battery.

Is this type of alternator the opposite of the 'constant magnetic' unit found on other bikes? Wich does not require power to make power?

Not really the opposite, just a different type with an excited rotor that can be controlled to give more output when required.

Why did they choose this type for our sukis?

Because it's better.

As discussed in another topic here on the forum. I'm thinking of improving the ignition system on my 550, using a relay for the coils, providing them with current directly from battery. What relay would you recommend for this?

As high a contact rating as possible with a 12vDC coil. Contact ratings are different for AC and DC so make sure it has a high DC rating.

[jabcb]

GT550 alternator……….
Your alternator is similar to what cars were using at the time.
The voltage regulator controls the voltage by adjusting the alternator's output.
This approach allows for alternators with lots of reserve capacity.

The T-series twins use alternators with permanent magnets.
The alternator output is simply a function of engine rpm.
These bikes have rather meager alternators so it doesn't take much to control voltage.
The T250 relies on just the battery to control voltage while the T500 has a small voltage regulator that turns excess power into heat.

Many modern bikes use permanent magnets & have high output alternators.
They have rectifier/regulators with cooling fins so they can turn a lot of excess power into heat.

The bike manufacturers are starting to adopt a relatively new rectifier/regulator design that allows them to control the output of high output alternators that have permanent magnets.

Use of relay for ignition………
The GS-series Suzukis have more complicated wiring than your GT550. As a result they tend to have a bigger problem with voltage drops as the bikes age.
Its fairly common to use a relay to power the coils on GS-series bikes.
Typically they use a 12V 40amp "Bosch-style" relay that commonly available at auto parts stores.

[tz375]

I typically wire in a 20 amp Micro relay, but almost any automotive 4 post relay will work. 40 amp is also very small if you like a higher rated unit.

http://www.easternbeaver.com/Main/Elec_ ... elays.html" onclick="window.open(this.href);return false;

[CBWELLS]

Just an addendum to whats been said already.
1] The older generation system with the brushes to the rotor provides for a controlled rotating magnetic field, which in turn allows a controlled output from the fixed stator winding. This system is either on or off depending on the voltage regulator & tends to be ON MORE when the engine speed is slower & as electrical load increases. This ON/OFF action is sometimes noticeable, especially at night when the rider can notice the lights pulse bright for a couple seconds then return to a less bright condition. It is "better" in the sense that it only produces electricity as it is needed (i.e. as battery voltage droops the system boosts it up) & does not tend to over heat its components. The downside to this system is it is more complicated to manufacture with both rotor & stator windings AND brushes that tend to wear out & can become intermittent with age & contamination.

2] The newer system with the rotating permanent magnet, is simpler & cheaper to manufacture, & has no brushes to develop problems in the future, but as stated by jabcb, produces an output that is proportional to engine speed.... The faster it rotates, the more voltage comes out. Unfortunately, anything in excess of about 14.5 volts will not be tolerated by the rest of the bikes systems (lights, ignition, etc.). Consequently, the excess is "bleed off" by the regulator by simply shorting out one or two of the 3 generated phases as needed to keep the battery charge voltage to that same 14 to 14.5v range. This disposal of voltage by shorting causes heat in both the shorted windings, and in the regulator itself (hense the fins on the regulator). The down side of this system is that over time & in extreme riding & ambient heat, it tends to cook both the alternator windings and the voltage regulator. Many riders (myself included) have had to replace one or both items especially on bikes built after about 1978 when this system came into popular use. Some shops insist on replacing both, even if only one is clearly at fault. More $$ for them, more reliability for you since the other surviving item has surely been heat stressed & is somewhat more likely to fail in the near future anyway.

So, in a sense, the systems operate "oppositely" in that the old one is a "supply side" regulator that makes only what is needed, while the other is a "load side" regulator that makes more than is needed & throws the excess away.

By-the-way, on the newer system, adding accessories (lights, audio, heated clothes, etc.) up to, but not exceeding the system rating will actually make the regulator's job easier since there will be less excess voltage to be disposed AND it won't make the alternator work any harder, although at low engine speeds it may cause system voltage to droop a bit until speed increases.

Hope this helps!

[Alan H]

Just an addendum to whats been said already.
1] The older generation system with the brushes to the rotor provides for a controlled rotating magnetic field, which in turn allows a controlled output from the fixed stator winding. This system is either on or off depending on the voltage regulator & tends to be ON MORE when the engine speed is slower & as electrical load increases. This ON/OFF action is sometimes noticeable, especially at night when the rider can notice the lights pulse bright for a couple seconds then return to a less bright condition. It is "better" in the sense that it only produces electricity as it is needed (i.e. as battery voltage droops the system boosts it up) & does not tend to over heat its components. The downside to this system is it is more complicated to manufacture with both rotor & stator windings AND brushes that tend to wear out & can become intermittent with age & contamination.

Not really, it's 'high' or 'low' output, not on or off as the voltage to the rotor (and thus the magnetism) is controlled, not switched on or off. It shouldn't pulse as there is a hysteresis between the high and low outputs which should be half a volt difference at least. If it pulses, then the settings need adjustment.

2] The newer system with the rotating permanent magnet, is simpler & cheaper to manufacture, & has no brushes to develop problems in the future, but as stated by jabcb, produces an output that is proportional to engine speed.... The faster it rotates, the more voltage comes out. Unfortunately, anything in excess of about 14.5 volts will not be tolerated by the rest of the bikes systems (lights, ignition, etc.). Consequently, the excess is "bleed off" by the regulator by simply shorting out one or two of the 3 generated phases as needed to keep the battery charge voltage to that same 14 to 14.5v range. This disposal of voltage by shorting causes heat in both the shorted windings, and in the regulator itself (hense the fins on the regulator). The down side of this system is that over time & in extreme riding & ambient heat, it tends to cook both the alternator windings and the voltage regulator. Many riders (myself included) have had to replace one or both items especially on bikes built after about 1978 when this system came into popular use. Some shops insist on replacing both, even if only one is clearly at fault. More $$ for them, more reliability for you since the other surviving item has surely been heat stressed & is somewhat more likely to fail in the near future anyway.
So, in a sense, the systems operate "oppositely" in that the old one is a "supply side" regulator that makes only what is needed, while the other is a "load side" regulator that makes more than is needed & throws the excess away.

By-the-way, on the newer system, adding accessories (lights, audio, heated clothes, etc.) up to, but not exceeding the system rating will actually make the regulator's job easier since there will be less excess voltage to be disposed AND it won't make the alternator work any harder, although at low engine speeds it may cause system voltage to droop a bit until speed increases.

Hope this helps!

The active type of system is very reliable so long as the brushes are checked during normal servicing intervals. It is more economical in engine power (and fuel too, which is very important with petrol a over £6 a gallon here in the UK.)
The permanent magnet type (actually the oldest system after dynamo) makes the alternator work hard all the time, not just when needed because it works flat out all the time, wasting engine power to spin it in the first place. Remember that (say) 250 watts is a third of a horsepower which has to come from the engine in the first place. Why do you think that GP bikes don't have generators? They either run a small magneto system, or total loss battery and change the battery between races.
Usually a Zener diode assembly is connected across the battery, so that when the charging (and battery) voltage exceeds a fixed value - 13.7v or thereabouts IIRC - the excess is allowed to pass through the Zener to earth. This makes the diode very warm, which is why it used to be fitted under the headlight and heavily finned to help keep it cool. It HAD to be very well earthed as did the battery or the battery would still boil and the bulbs would pop. If the battery was charged and the bike isn't using any lights, then maybe 200 watts has to be 'leaked' through the diode and be wasted in heat. 200 watts is quite a bit of heat to get rid of as well as a waste of engine power.

[jabcb]

The active type of system like the one in the GT550 are still used in cars & trucks. Definitely very reliable in those vehicles.

A big plus for bike alternators with permanent magnets is that they can be designed to be more compact.
The GT-series triples & the GS-series fours both have their alternators on the end of the crank.
The permanent magnet alternators on the GS-series bikes are much narrower than the those on the GT-series bikes.

Modern electronics can eliminate the wasted power & heat associated with permanent magnet alternators.
Interestingly, the Toyota Prius was designed for maximum efficiency & it uses permanent magnets.
http://en.wikipedia.org/wiki/Hybrid_Synergy_Drive

[CBWELLS]

In response to AlanH, "Not really, it's 'high' or 'low' output, not on or off...". I agree, but in my defense, I was trying to keep it a simple explanation! OFF is too strong of a description on my part.

When system voltage starts to get too high, the regulator's "points" switch OPEN, but there is still a parallel resistance in the regulator that provides some "bias" current to the alternator field to keep it moderately excited & maintain system voltage. When or if that excitation is not adequate to maintain the battery voltage causing it to droop (such as idling with the lights on, etc.) the regulator's points will then switch CLOSED to bypass that resistance. This increases the field current which then increases the 3-phase output from the alternator and ultimately increase the voltage to re-charge the battery. AlanH correctly points out that visible pulsing probably indicates a problem in the regulator (probably an OPEN regulator resistor... & I need to check that on my GT550)!

I also agree with AlanH's 2nd paragraph of comments, and I would add that the ZENER circuit he describes is called a "shunt regulator" as it "shunts" electrical power to away from the system when connected as in his description. An improved evolution of this is called a "crowbar" regulator & uses either Silicon Controlled Rectifiers (SCRs) or power Transistors in a solid-state device to do exactly the same thing...waste excess energy to maintain proper system voltage... which is what the permanent magnet system does & I was describing in the 2nd part my first post.

Lastly, I prefer the active system. I feel the brushes & slip rings are more reliable than it is to constantly stress the alternator winding & the regulator by pissing away energy that wasn't needed in the first place. I bet the MFR finds it cheaper to use the permanent magnet system. It's "reliable enough" to get the bikes past their warranty period when the MFR and the repair shops won't mind fixing the dead ones to the tune of $200 to $400 each! That's pretty easy money & it comes out of OUR pockets, not theirs!

[Alan H]

several comments above!

Hopefully I didn't come across as I know it all. That wasn't meant at all, but my job as Electrical and Mechanical Commissioning Engineer for the last 25 years (plus another 22 years 'learning' before that!) give me the experience to be able to be picky (silly old fart disease I'm afraid!!) with comments.

I try to avoid being too exact in technicalities as most folks just go zzzzzzzzzzz after a couple of sentences of bumf, but sometimes I just have to say, as I get so passionate about certain things. Nice to see that some folks can actually read between the lines and understand the technicalities of my comments - thanks, I appreciate that when it happens.
I still work as senior UK engineer at the company I now work for, (a German company, with world wide expertise of compressors and blowers) and hopefully know what I'm on about.
Regarding the 550 alternator, I actually did a thesis on the workings of it with the up and downsides in about 1974 when I was doing my Engineers Cert! There are better systems, but cost comes into it, as with everything nowadays.
Frightening how the years have passed.
Still like what I do (retire in a couple of years, woohoo!!) then I can get on with the serious stuff like the 4 x 550s, RIB with a 130HP V4 two stroke, scuba diving, model helicopters, travel the world, caravan, 4x4, lowering of levels in scotch whisky bottles and several other 'hobbies'.
Roll on retirement.

jaccb.
Fair comment, but WTF designed a prius?
A blind donkey or an accountant?
Certainly no-one with a soul or any interest in engines.
I'll keep my V6 Santa Fé, V8 Rover and 3 cylinder and V4 2 strokes thanks.
Intercourse the polar bears and tree huggers.

[jabcb]

Alan H, you might find the Shindengen rectifier/regulator wiring diagrams interesting:
http://www.shindengen.co.jp/product_e/e ... talog.html

Their 3-phase series-style regulator/rectifier is popular on the Suzuki GS forum.
Unlike shunt style designs, the series style design controls the voltage by limiting the current delivered by a permanent magnet alternator.