by Liberty4Ever » Tue Feb 19, 2013 2:23 pm
These hour meters are very simple two terminal devices. For the AC meter, apply the specified AC voltage across the two terminals whenever you want to measure the time. The DC version is the same, only with DC power. For the DC version, you'll probably need to observe the proper polarity (positive voltage to the plus or red terminal, and negative voltage or common to minus or black). The AC version is typically used at some location on the incoming AC power line, and the DC version is typically used after the power supply converts the incoming AC into DC to power the various subsystems components or generate control voltages.
The only real complexity is deciding what you'd like to time. I'll probably have two hour meters on my laser, with one recording machine ON time (how long the laser has been powered), and the other recording laser time (how long the laser tube has been powered, as measured from the laser power supply's enable signal), It can sometimes be useful to know how much time the laser tube has been operating, when reporting a laser tube failure to the manufacturer, or when scheduling periodic maintenance to the laser subsystem.
Apparently, I didn't build that!