Ignoramus16649 wrote:
I have been cleaning up this Quincy install by properly tucking cables
into conduits, wiring things correctly, using crimped terminals where
appropriate, etc.

My Quincy compressor comes with a nice old Size 2 electrical control.
The nice thing about it is that overloads are adjustable by turning
little knobs, so I do not have to buy overload heaters. At 220v, it is
rated at up to 15 HP. The motor I have on the compressor right now, is
10 HP.

The compressor was wired for 440 volts originally and had a 7.5 HP
motor (much bigger than my current 10 HP motor). So the overload setting
that it had set, obviously would not match. For for the first few
weeks I did not use overloads by bypassing them, but now I want to set
them properly.

The question is what is "properly".

I'm no expert, but I think I'd do it by looking
up the full-load and locked rotor current draw
of the motor and setting the overload current
somewhere in between.



My thinking is that in this context, it means that the compressor can
reliably restart at the restarting pressure (100 PSI or so), but at
the same time, overloads should pop in a second or so if the motor is
stalled.

I can reproduce a stalled motor very easily, by stopping the
compressor when there is pressure in the tank, and restarting within a
minute, before unloaders bleed enough air. (I hope that it is not an
indication that something is wrong with unloaders, a separate topic)

I already set the overloads, apparently high enough so that they do
not pop when the motor is running regularly. So, therefore, to me the
procedure now would be to turn them down, to the point when they
reliably pop on a stalled motor, but when compressor still starts
well.

Am I missing something and is that too unscientific?