Re: Cut Out Bench Test

Posted by John Regan on July 26, 1998 at 07:59:18

In Reply to: Re: Cut Out Bench Test
posted by DJ.Voyce on July 24, 1998 at 01:09:18

The normal cut in voltage for the cutout is 7-9 volts and officially when on the car the cutout should open before the discharge reading on the ammeter reads 4 amps as the engine RPM is slowly lowered.This was the procedure during all of the T era and into the A era.
I would point out that these voltages were for the old 6v batteries and modern batteries would probably prefer a lower setting.Settle for any pull in voltage above 6.8 and less than 8.Also for cars that are run 90% daytime driving - set 3rd brush for no more than 4-5 amps.I prefer 3-4 amps to save battery, generator and cutout.Modern driving is not as "slow" on the average as was the norm during the era of your car so high settings of over 10 amps as called for in original service bulletins will simply overcharge your modern battery.
All relays have a higher cut in voltage (points closing) than drop out voltage so don't even try to make them the same.The typical cutout coil is about 50 ohms resistance so it will draw about .12 Amps when it pulls in so you need only a variable (6-10v) voltage source that can deliver at least that much current in order to operate the thing.
Give serious thought to using a solid state device for your cutout since the penalty for having a mechanical cutout stick "open" is a burned out field coil in your generator and sooner or later they will all stick open.If you ever notice that your cutout is starting to stick "closed" (discharge on ammeter when all systems are off) and you tap on the side of it to free it - DO NOT PUT OFF SERVICE ON IT since the next event shortly to come is for it to stick open and when it does your generator field is history.
Good luck
Voltage regulator for 3 brush generators

Follow Ups:
Re: Cut Out Bench Test DJ.Voyce July 27, 1998 at 00:41:11(0)

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