Re: Generator question - negative current
Posted by HH56 On 2023/11/23 22:12:10
While you could have an intermittent short somewhere in the light wiring that is tripping the switch protection, the mostly repeatable on/off symptom after a few minutes of operation is also very typical of a weak circuit breaker. As circuit breakers age they tend to change characteristics, usually tripping at a lower amperage than their rating. This is often seen in postwar models and while most earlier models use what Packard called a thermostatic overload relay which is an integral part of the switch, it operates very much like the later breakers. Current flowing thru a bimetal strip heats the strip and the more current, the hotter it gets until strip bends and opens a contact.
There is an adjustment screw for the earlier strips although to get an accurate adjustment special equipment is required and Packard says the adjustment should not be changed. This is probably due to dealers not having the equipment to measure and vary the current thru the switch. I don't know how easy it is to access the switch and adjustment screw in the car. If you do not find any short, you could try another switch as Packard recommends or if the switch and screw can be accessed maybe go ahead and try to move the screw a tiny bit one way or the other and see if the problem goes away or gets worse. As I recall, the adjustment screw looks like a small slotted setscrew with a nut on it. The screw will be electrically hot so be sure to disconnect the battery between adjustments.
It will not take more than a very slight amount of adjustment so if you do try, only go maybe a 1/16 to 1/8 of a turn and keep track of the amount and direction so you do not get it so far out current protection becomes worthless.
Attach file:
switch.jpg (165.30 KB)
There is an adjustment screw for the earlier strips although to get an accurate adjustment special equipment is required and Packard says the adjustment should not be changed. This is probably due to dealers not having the equipment to measure and vary the current thru the switch. I don't know how easy it is to access the switch and adjustment screw in the car. If you do not find any short, you could try another switch as Packard recommends or if the switch and screw can be accessed maybe go ahead and try to move the screw a tiny bit one way or the other and see if the problem goes away or gets worse. As I recall, the adjustment screw looks like a small slotted setscrew with a nut on it. The screw will be electrically hot so be sure to disconnect the battery between adjustments.
It will not take more than a very slight amount of adjustment so if you do try, only go maybe a 1/16 to 1/8 of a turn and keep track of the amount and direction so you do not get it so far out current protection becomes worthless.
Attach file:
switch.jpg (165.30 KB)
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