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TR2/3/3A TR3A Lucas Voltage Regulator Adjustment

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houleyh

Senior Member
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Maybe someone can help me.

I followed the Lucas Procedure to test/adjust the regulator and cut-off. I am a bit confused in the last steps.

1- Why do we have to set the regulator at 16.0 - 16.5 Volts. It looks pretty high to me.

2- Also, once the regulator is set at 16.0 - 16.5 volts, how can we verify the adjustment of the cut-off at 12.5 - 13.5 Volts. (After the regulator's adjustment, I have 16.0 - 16.5 Volts spitting out.??)

Anyone can help?

Thanks
 
The voltage is set way high because the voltage regulator doubles as the current regulator; and you are setting it with no current going through the winding. IOW, the regulator actually regulates the sum of voltage and current, so with a moderate amount of current flowing, the set voltage will drop to a more appropriate value.

To check the cutout, you need the engine turning slowly enough that the generator only puts out 12-13 volts. The voltage regulator is ineffective at this point, it's points should be fully closed so that the generator field gets all the voltage being produced by the armature.

If that is not possible for some reason, and you really want to check it accurately, you'll need to rig a way to reduce the output voltage. Try blocking the regulator contacts open, and insert a resistance (perhaps a stop light bulb) between the F and D terminals to supply a reduced field current.

But once you've finished adjusting the regulator, you should remove the cardboard from the cutout contacts, which means you aren't going to see 16 volts any more unless your battery is bad.
 
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