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Generators & Electric Motors General Discussion

Need Voltage Regulator


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  #1  
Old 08-27-2006, 08:08:21 PM
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Default Need Voltage Regulator

I need to get a regulator for this genset. I use a reostat to adjust output volts now as the original regulator was missing when I got the set. It runs great and makes power, but does not self adjust to load changes. THANKS
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Old 08-27-2006, 08:20:28 PM
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Default Re: Need Voltage Regulator

Sorry for the brief message, but my computor keeps going off line and thinks it is still on. I will try a couple more pics and give you more info. The reostat I'm using is rjs500, 500 ohms,0.316a. It is capable of adjusting thru the range I need. I will try to supply more info as needed. THANKS again, Paul
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Old 08-28-2006, 09:07:03 AM
Jim Rankin Jim Rankin is offline
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Default Re: Need Voltage Regulator

What is the voltage at the point where you have the resister? I see the DC exciter is 125VDC, can't see the amp rating in the picture. I have a couple of Basler KR7FF regulators and they are available on ebay pretty regular. I believe that regulator would replace the DC exciter and it's regulator and supply the 125VDC field up to 3.5 amps output.
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Old 08-28-2006, 04:15:30 PM
mylesdw mylesdw is offline
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Default Re: Need Voltage Regulator

So am I right in thinking that on that style of Century alternator with the built-in DC exciter that voltage to the AC field windings is actually regulated by adjusting the voltage to the DC field windings and the DC generator output drives the AC field directly? If I understand correctly, a solid state regulator can replace the DC exciter and its 'mechanical' regulator completely and would drive the AC field directly. Where does the regulator get its power from? Is this the residual magnetism and 'flashing the field' thing?
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Old 08-28-2006, 08:51:33 PM
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Default Re: Need Voltage Regulator

Jim, the tag on the exciter says 4. amps. I fired the unit up tonight and took readings at both sides of the resistors ( 2 fixed and the reostat ). From the F1 terminal to neuteral was -5 volts, A2 to neuteral was 54 volts, and F1 to A2 was 60 volts. The resistors are all in series between F1 and A2. The only load I had on it was a 15 hp 3 phase motor running free. In case anyone is interested, the engine is a Waukesha 130HL spark ignited diesel built in march of 1943. Hope these numbers help you understand this thing. THANKS again and special THANKS to Harry for this board. Paul
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Old 08-28-2006, 09:11:40 PM
Jim Rankin Jim Rankin is offline
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Default Re: Need Voltage Regulator

Quote:
Originally Posted by mylesdw
So am I right in thinking that on that style of Century alternator with the built-in DC exciter that voltage to the AC field windings is actually regulated by adjusting the voltage to the DC field windings and the DC generator output drives the AC field directly? If I understand correctly, a solid state regulator can replace the DC exciter and its 'mechanical' regulator completely and would drive the AC field directly. Where does the regulator get its power from? Is this the residual magnetism and 'flashing the field' thing?
I'm no expert, but I believe you are correct on all counts, though there may have been different ways of doing it. The old style mechanical regulator initially gets it's power from the residual voltage created by the residual magnetic field in the DC exciter.

Some sets have a flashing relay or switch terminal that energizes the field while the starter is actually cranking the engine over. By the time the starting switch is released, the engine speed is coming up and the exciter is making voltage which feeds back through the regulator. It would take a wiring schematic to make sure how all this is done in a specific set.

Most modern sets did away with the rotating DC exciter generator with it's brushes and commutator and rectify the AC output of the stator or the AC output of a dedicated winding in the stator to power the regulator and field. This is a so called static exciter vs the rotating exciters.

When heavy surge demand is anticipated, modern sets are equipped with a permanent magnet alternator to power the field. This independent source of power for the field is less affected by starting surges of large motors or other large block loads that cause stator output voltage to sag. So it looks like to me we have gone full circle and are back to the rotating exciter, without the brushes and commutator, but with rectifiers instead. Much more reliable and cheap now-a-days.

Then you get into brush and brushless exciters, and that is where the rub is when converting to modern regulators. The not so old statically excited brush type sets I have seen tend to have high amperage-low voltage exciters compared to the brushless which can multiply the output of a small regulator through the brushless exciter stator and exciter rotor to create the power necessary for the main field.

Finding a modern, off the shelf, regulator capable of powering some fields directly is hard to do. So you wind up with a complete regulator and exciter system like the Powertronics system that has been mentioned on the board. Still can be cheaper than repairs to some older regulator systems and you have modern equipment with tech support etc available.

Just my experience, and I'm learning too. My generators include a `44 Buda with a Century generator end, Late `60's early `70's Onans and a Caterpillar
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Old 08-28-2006, 09:34:03 PM
Jim Rankin Jim Rankin is offline
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Default Re: Need Voltage Regulator

http://www.smokstak.com/forum/showth...t=buda+century

It has a GE automatic regulator about as big as a loaf of bread and a manual regulator knob with an "auto/manual" switch. The manual setting seems to respond to load pretty well too, so I'm not sure what it actually uses, a variable resister or something else.
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Old 08-30-2006, 02:01:24 PM
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Default Re: Need Voltage Regulator

The Basler KT-3B is a transistor replacement for the old mechanical regulators. It is rated 125 v.cont 200 max armature, 2 amps forcing 6 amps and a minimum 34 ohm field res. This may work but Basler likes their stuff a lot. I believe the last time I priced one it was around $400.
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Old 08-30-2006, 03:07:39 PM
BenHuebner BenHuebner is offline
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Default Re: Need Voltage Regulator

Wouldn't it somehow be possible to make use of the Rotating DC exciter generator by using a modern regulator on the field coils of the excitor. The big question would be how to hook it in with the brushes, field coils, shunt coils etc.
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Old 08-30-2006, 04:48:09 PM
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Default Re: Need Voltage Regulator

Thats what the KT-3B does. It senses the voltage in one phase of the stator output and has taps for 120/208/240/416/and 480v. 3 volts residual will produce sufficient armature voltage which powers the regulator to control the exciter field. It is a direct replacement for the old electromechanical units used on the older brush type dc exciters.
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