Bench Power supply, basic question

Greetings, I'm confused by the simplest things sometimes, so please don't laugh. I got a bench power supply (from the local hamfest) that I think works OK, I'm just not sure how to use it. It has three outputs, Negative, positive and ground. There are two meters, volts and amps and two knobs, volts and amps. When I set the voltage to (say) 5, then the meter says 5 and my multimeter says 5 volts from negative to positive. From positive to ground, the multimeter just jumps all over the place.

Is this proper operation? If it is, then when I'm building a circuit that shows ground and +5, then do I hook the circuit ground up to the supply negative and the +5 in the circuit to the positive on the supply? What's the supply ground all about anyway? Inside the case, the green wire from the line cord attaches to the case and the ground output.

Thanks, the next question will be how to use the current knob, does that act as a limiter?

 

The supply is operating correctly. The voltage is generated between the (+) and (-) terminal and is floating, i.e. no reference to ground. The ground is a chassis ground and can be used to reference either side to the green wire ground of the house. It is often used for electrical safety. Faults are best shunted to a true ground.

Your statement of supply connection to a circuit is correct. (-) to GND and (+) to supply.

The current knob will, as you suspected, act as a limiter for the output current.

 

Is that little metal plate I see in some pictures the way to link the minus to the chassis ground? I can fabricate something like that in case I ever need it. Thanks for your help.