Posted by JMOR on July 10, 2009 at 07:49:41 from (72.181.158.237):
In Reply to: Adjust/repair V/R? posted by Jeff Z. on July 10, 2009 at 06:06:04:
GordoSD said: (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
The 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.
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