Interpreting HP ratings of a pressure switch label?

Question

I'm trying to interpret the voltage/HP table given on the badge of an air compressor pressure switch. Here's the badge:

What is confusing is what this table is actually supposed to be telling me. The "axes" of the table are voltage vs. HP. The table itself is called "HP" ratings"... so I would think the VALUES would be HP. Instead, I can't figure out what they are. (They seem too small to be amperages.)

Also (secondary issue) the meaning of the DC column is not clear.

What do the actual values in the table mean?

Answer 1

It is a misprint. Here's a the badge from a similar model but without the same issue:

Somebody just typo'ed "PH" (for phase) into "HP" on the example in the question.

The table is actually VOLTAGE VS "POWER SOURCE" and the "output" values are HP ratings. This also explains the DC column, since evidently this switch can be used for either AC or DC motors.

Answer 2

What do the actual values in the table mean?

The values in the table are the maximum single-phase, 2 or 3 phase and DC motor horsepower ratings that the switch can safely and reliably handle at the given voltage ratings. They are based on an analysis of the expected usage duty, motor current, motor power-factor for the AC columns. That includes the expected motor inrush current for starting and the difficulty of breaking the arc with and inductive load when stopping. This is the usual rating method used in the US for motor switching contacts. In other parts of the world, there is a system of duty class codes.