Adjust/repair V/R?

The two year old voltage regulator I just removed from my SH is shiney new inside. There are two sets of points in there. One is loaded shut, and I assume takes a current to open it. The othere is loaded open and conversely current needed to close it. They sre both adjustable.
So exactly how do they work? How to bench test these?

Gordo

The normally open points are the "CUTOUT" that CONNECTS the generator to the battery while it's charging and disconnects the generator from the battery when it's NOT charging.

Those points should initially close when the generator begins charging and the voltage comes up to about 8 Volts, then drop out when the generator voltage drops about 1-1/2 Volts below the closing voltage. (These are generic numbers for a 6-Volt system there would have been EXACT values for the OEM regulator shown ion the service manual.) Increasing the spring tension on the cutout points cause later closing and earlier opening.

The other relay (in this 2-relay regulator) controls charging Voltage AND limits charging current. It is wound with a SHUNT coil of fine wire that produces increasing magnetism as the charging voltage rises and a SERIES coil of heavy wire that produces increasing magnetism as the charging CURRENT rises. When the magnetism produced by the coil is strong enough to pull the points apart, the field is no longer fully grounded, but now has a resistor in series to ground, dropping the charging rate. The points actually vibrate, controlling the charging rate at the desired level.

Increasing spring tension holding those points closed INCREASES the charging rate.

Gordo -

The relay with its contacts held open by a spring is the cutout relay. Its purpose is to keep the battery from discharging through the generator when the engine is stopped. The cutout senses generator output and closes to connect the generator to the battery when the generator voltage exceeds the cutout's setting.

The other relay is the actual voltage regulator. It senses system voltage - its contacts open when battery voltage reaches the VR's setting (about 7.2 volts for a 6 volt system; about 14.4 for 12 volts). When open the VR's relay contacts interrupt current in the field circuit by inserting resistance into the circuit. This in turn causes generator voltage to drop.

When the VR relay is operating its contacts open and close very rapidly - many times a second.

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Bench testing and adjusting a VR requires specialized instruments and a high output variable voltage power supply.

However the regultor voltage relay setting CAN be adjusted on the tractor if you have a good quality, accurate VOM or DVM and some patience.

Setting the cutout is more fussy. And if you don't get it exactly right you risk a dead battery and possibly a burned out generator.

Make sense?

(quoted from post at 09:06:04 07/10/09) The two year old voltage regulator I just removed from my SH is shiney new inside. There are two sets of points in there. One is loaded shut, and I assume takes a current to open it. The othere is loaded open and conversely current needed to close it. They sre both adjustable.
So exactly how do they work? How to bench test these?

Gordo

Click to expand...

he set you call 'loaded open' is the cut out function. Its coil (voltage sensing shunt winding) is a very fine wire connected to the generator armature and when the gen voltage reaches some level slightly greater than the battery voltage (it doesn't know the battery voltage, but the designer chose a voltage greater than typical battery voltage, ~6.5 to 7.0), this coil pulls those contacts closed, thus connecting the generator's armature to the battery. This should then result in the generator supplying current into the battery for charging. Now, when the engine slows enough or stops, such that generator is no longer supplying current into battery, the battery will now try to supply current into the generator, thus discharging battery & heating the generator, both of which must be stopped by opening those same cut out contacts. This is done primarily by another winding (of much heavier wire) wound on top of the voltage sensing shunt winding), through which the current from generator armature flows to battery & visa verse upon engine slowing/stopping. In the charging direction, it aids the voltage sense shunt in holding cut out contacts closed, BUT when the direction of current reverses (batt discharging back thru gen armature), then this magnetic field opposes the voltage sense shunt field and overcomes it thus releasing the cut out armature plate & opens the contacts which had been connecting arm to battery.
The other assembly with the "loaded closed" contacts is the voltage regulator function. Some regulators are designed where this unit has a dual function of voltage AND current regulation. The voltage regulation is via another fine wire shunt coil, again sensing voltage and controlling this set of contacts which open & close the field circuit of the generator. When the battery voltage reaches a level deemed to be fully charged (typically 6.9-7.6 range), these contacts are pulled open, thus reducing the generator field current which in turn reduces the generator armature output and prevents overcharging the battery & boiling acid all over the place. This is a bit more involved than the last sentence makes it sound, in the to gain a 'finer' control of battery voltaage, the field contacts really have more or less 3 states. Open (minimal gen output), closed (full output) and a vibrating mode where they may be opening & closing at hundreds of time per second. This vibrating modes provided levels of output between minimal and full. Additionally, there is a resistor on the back of the case which supplies a minimal field current when VR contacts are open AND provides some arc protection for the VR contacts, against the inductive kick back of the field as these contacts open. Some of the kick back energy is absorbed by the resistor whereas without it all such energy would be available to arc the contacts. Additionally, to protect the generator from destructive over current, some regulators have a second current winding over the VR unit voltage sensing shunt coil whose function is to aid controlling the VR contacts such as to reduce field current when armature current become too high.
There may be other nuances, but in a nut shell, that is my story.
Adjustments. It is not as simple as it sounds & without a lot of experience, time, patience, you will likely fail. Some call it a lost art.
I have some info, but nearly everyone will tell you that you should just buy a new one. Keep in mind that the regulators in this PDF file will almost certainly NOT be a match for your particular regulator. There are many variances in regulator designs. Almost all later regs dispense with adjusting screws & utilize careful bending of spring anchors to alter tension. Circiuits also differ considerably. If you want the PDF document, e-mail me, as I do not know of a way to put it into this posting.

OK. Based on the fact that the VR was working just enough to "maintain" the battery, but not charge it up from low state, It could be either one of those contacts.
There's an old timer in town that has a magneto shop, repairs all things electrical, I'll take it in and let him play with it. Need a haircut anyway. His wife cuts your hair while he does your repairs.
Thanks for the info. I just remebered I used to tweak up the VR on my flathead Ford 6V system. Dad had a little ammeter to hook up to it.Wonder where that went? I still have his dwell-tach, and big CHROME Sun timing light.

Gordo

Well stated ! Jim

Coming from the well respected Jim Nicholson, I really appreciate that! Thank you.

Yes, I couldn't have said it any better myself. To adjust the voltage you need a voltmeter hooked up to the battery & either adjust the screw or bend the tab to the voltage needed (do this while it is running & charging) keeping in mind it may change when you put the cover back on. You need to tweek a little extra to overcome this. Good luck!

Excellent explanation of the operation of a cutout and combination voltage current regulator. Sounds like it came right out of the USAF correspondence course I took in 1957. Dealership I worked at had a nice portable Allen volt , amp test setup specially for reglators and generators and I used it a lot, even on new reglators, but like has been said, that is a lost art now .

OK, all you 6v guys, print these and file in your appropriate folders. Lots of great info here. Thanks to all.
I ran it by the mag guru in townand he said he needed the generator with it. So just got a haircut and left. (His wife will cut your hair even if he isn't working on your stuff.)

Gordo