A power station is, simply, a large frame that holds a barbell (sometimes referred to as an Olympic bar), and can be used to do several exercises. Some power stations have fixed, adjustable machine weights, whilst others have a free bar. The fixed machine weights are safer and easier to use, but more experienced weight lifters may prefer a free weight.
Squatting with a power station
Using either a free weight barbell, or the fixed weights, the power station can be used to add a weightlifting element to squat workouts. Weights are attached onto the barbell held by the power station, which you rest on your shoulders as you squat down (making sure to not bend your back), before standing back up, returning to the start position to complete one repetition. There are grooves at different heights on the power station for you to rest the bar on.
This exercise works the hamstrings, quadriceps, gluteus maximus and core, as well as many other secondary muscles, making it a great workout for most of your body.
Bench press/Chest press with a power station
For the bench press, you need an exercise bench to be placed under the power station. Lying flat on your back, you firmly grasp the weighted barbell, which will be suspended directly above your chest, and lower it towards your body, bending your arms in the process. You then extend your arms almost fully as you raise the bar back up above your chest, before lowering it back down to complete a rep.
This exercise will work your pectoral muscles (pecs), triceps and front deltoids predominantly.
Power station safety
You should never overload a power station with too much weight, especially if using free weights. Always balance the barbell with identical weights at both ends, and ensure they are secured before beginning the workout. You should also always use a spotter.